Studies on Australian and New Zealand Diatoms I.—Planktonic and Allied Species

Transactions and Proceedings of the Royal Society of New Zealand, Volume 85, 1957-58, Page 483

Studies on Australian and New Zealand Diatoms I.—Planktonic and Allied Species By L. H. Crosby and E. J. Ferguson Wood [Read before Auckland Institute, March 19, 1958; received by the Editor, October 10, 1957.] Abstract This paper contains descriptions of 135 species of plankton diatoms, together with a few epontic and benthic species, which have been recorded from Australian and New Zealand waters, as well as a list of previously recorded species of the genera considered, together with their location and authority. The species described are illustrated. One new species of Cerataulina is described. An outline is given of the significance of species of phytoplankton diatoms as indicators of plankton communities associated with certain water masses on the Australian coast. Contents Introduction. Source of Material. Morphology of Diatoms. Classification. Previously Recorded Australasian Diatoms. Key to Genera of Diatoms Encountered in the Present Investigation. The Diatom Species. Diatoms as Indicators of Water Movements. Seasonal Variation in the Planktonic Diatom Flora of Port Hacking. Introduction The material used in these studies represents collections from the Antarctic to Darwin, and from Shark Bay to the Solomon Islands and New Zealand. Samples from northern Australia are few, and possibly not fully representative of the region. However, the neighbouring Java Sea has been covered by Allen and Cupp (1935). Source of Material Oceanic phytoplankton has been collected by F.R.Vs. “Derwent Hunter,” “Warreen,” “Stanley Fowler,” “Liawenee,” “Gahleru” and “Fairwind,” by R.R.S. “Discovery II,” the Royal Danish research ship “Galathea,” and by vesels chartered in various Australian ports. Material from New Zealand has been forthcoming from the Institute of Oceanography. Stations have been occupied right round Australia, in the Antarctic, off Papua, New Guinea, the Solomon Islands, in the Coral Sea, the Tasman Sea, and off New Zealand. North Australian waters are represented by the few cruises of the “Wareen” and the “Stanley Fowler,” and some collections from Thursday Island. Estuarine phytoplankton has been most extensively collected from the south-east of Australia from Port Phillip to Moreton Bay, but Swan River (Western Australia), Storm Bay (Tasmania), Heron Island (Queensland), Lae, and Rabaul Harbours (New Guinea) are also represented. Phytoplankton was collected by means of silk nets, firstly by Discovery type “N50” nets with 200 meshes per inch, later by a net with a 6in ring and silk with 170 meshes per inch. The smaller net, by more adequate filtration, caught nearly as many cells as the Discovery net under the same conditions, and was much easier to tow and handle. Qualitatively, there was little if any difference.

Morphology of Diatoms Diatoms, being plants, have a protoplast containing a nucleus, vacuoles, chloroplasts and frequently pyrenoids. The storage product is oil, which assists in flotation. The plastids vary in number and form, and the shape may be characteristic of a species (e.g., the stellate plastid of Striatella unipunctata) or a group of species as in the genus Chaetoceros. In many planktonic diatoms, the cells are highly vacuolate, and the protoplasm consists of a narrow region adjoining the cell wall with a reticulation of threads in the central, largely vacuolate portion as in Rhizosolenia. The cellulosic cell wall, which surrounds the protoplast, becomes impregnated with silica, which is taken from solution by the diatom, and it is this siliceous exoskeleton which is of primary importance in identification, since it is a permanent record, even in fossil forms. Many diatoms–e.g., the naviculoids, some nitzschias and pleurosigmas, are motile, but the mechanism of this motility is uncertain, though movement is made possible by the fact that the exoskeleton is not continuous. Diatoms reproduce by fission, which takes place perpendicularly to the pervalvar axis, by conjugation, and by auxospores. Microspores and resting spores occur. Because the siliceous skeleton or frustule consists of two parts or valves forming a “box” and “lid,” united by a girdle, division results in one cell of a pair being smaller than the parent cell, leading to a gradual diminution in size. When this diminution becomes critical, auxospores are formed, and these give rise to large cells again. This process is frequently seen in the genus Melosira. The view looking down on the valve is known as the valve view, that looking sideways at the two valves and the girdle is the girdle view. Diatoms have three axes of symmetry at right angles to each other. The pervalvar axis runs through the centre of the two valves. In Coscinodiscus, Melosira, and many other “centric” forms, the two axes through the girdle are equal, but in the lanceolate forms there is a distinct longitudinal as well as a transverse axis. In some species of diatoms–e.g., Grammatophora, Striatella, there are lacunate partitions perpendicular to the pervalvar axis. These are septa, and are often diagnostic. The markings and sculpture of the surface of the frustule are used as diagnostic characters. Bands parallel to the girdle plane are known as intercalary bands. The surface of the valves and girdle may be sculptured with areolae or puncta, which may be arranged in longitudinal, transverse or diagonal striae. Ribs or costae are thickenings, usually radial or transverse. Actually, the markings on the frustule are thickened or thin areas, and some of them have pores through which the cell is in contact with the exterior. A number of structures is connected with the valves. Processes and spines are frequent in some genera–e.g., Biddulphia (which has both), Isthmia (which has the former), and Chaetoceros (which has the latter). In some forms such as Navicula, each valve has a slit known as the raphe. In other genera–e.g., Achnanthes, only the lower valve has a true raphe. In Navicula, the raphe is generally parallel with the longitudinal or apical axis, but in Pleurosigma, the raphe is sigmoid, and at an agle with the axis, in Nitzschia it is marginal, while in Surirella, it is borne on wing-like extensions (alae). The raphe may or may not be terminated by apical nodules, and there is usually a central nodule. The pseudoraphe is a convolution, usually longitudinal, of the valve surface. Classification The shape of diatom cells is characteristic, and Schütt (1896) divided the diatom into two morphological sub-orders, Centricae and Pennatae, according to whether they have or have not radial symmetry. Hendey (1937) has objected to the use of Schütt's sub-orders on the grounds that there are too many exceptions which have to be made to fit the scheme, and that etymologically the terms are misleading. Taxonomically, there is much to justify Hendey's view, though Schütt's divisions have some ecological advantage in that.

most of the planktonic forms are centric and most benthic and epontic forms are pennate. Because of its taxonomic advantages, we have accepted Hendey's families and have arranged our material accordingly. There seems, however, to be little justification for the large number of monogeneric sub-families that Hendey has introduced, especially as we have no assurance that a taxonomy based on skeletal structure has true phylogenetic significance as Boyer (1916) points out. Once again we are confronted with a group of organisms in which the classification cannot be assumed to be strictly Linnean (v Wood, 1953, 1954). The present system is essentially pragmatic, allowing us to make useful ecological observations, and to correlate present with fossil diatom floras, making interesting deductions therefrom as to the conditions under which the fossil deposits were formed. Previously Recorded Australasian Diatoms Although no systematic study of the diatoms of Australia and New Zealand has previously been published, except for a paper by Petit (1877) on the diatoms of Campbell Island and Foveaux Strait and several small papers on the diatoms of the Oamaru limestones by Grove and Sturt (1886–1887), a large number of species has been recorded over the years by European authors working over miscellaneous collections. The record of species given in this paper is doubtless incomplete, but has been made from the literature available to the authors. A certain amount of the synonymy has been checked, but, because of the difficulties involved in checking earlier work, and especially of the fossil species, we do not claim the validity of all the species recorded here. It is interesting to point out that Aulacodiscus beeveriae was originally described from the Northern Rivers of New South Wales as the type locality, and our only record of this species is from the Clarence River. Aulacodiscus margaritaceus, Campylodiscus crebrecostatus, Amphora arcta and other species of which their type locality is Australia have been found in our investigations, and no doubt, as time goes on, further previous records will be confirmed, and perhaps the synonymy simplified. The planktonic diatoms of eastern Australia were mentioned, but not exhaustively studied by Dakin and Colefax (1940), and collections from the Java Sea have been recorded by Allen and Cupp (1935). Mann (1937) has listed as Antarctic species forms which were collected by the British-Australian Antarctic Research Expedition on the run between Melbourne and Pedra Blanca (i.e., east Australian water) and in the West Wind Drift running north to Cape Leeuwin. As he has not recorded the stations it is impossible to evaluate his discussion on the “tropical affiliations of some of the Antarctic diatom Flora”. The writers examined some of the B.A.N.Z.A.R.E. material and found that the indicator species of the east Australian warm water system were present to between 44 and 46° S on the run east of Tasmania from Melbourne, while Mann's recording of Chaetoceros messanense suggests West Wind Drift (see also Wood, 1954). Key to Genera of Diatoms Encountered in the Present Investigation 1 Cells cylindrical or discoid Valve margin circular or oval 2 Cells not cylindrical or discoid 32. 2 Cells with peripheral spines longer than cell diameter 3. Spines shorter than cell diameter or absent 6. 3 Cells forming long chains attached by spines 4. Cells solitary or in pairs 5 4. Spines numerous, radiate at right angles to pervalvar axis Bacteriastrum. Two spines at each valve margin, usually at an angle to pervalvar axis Chaetoceros. 5 Long spines numerous, forming collar at margin of valve Corethron. One central spine and crown of spinules Ditylum. One excentric spine at apex of tapered valve Rhizosolenia. 6 Cells in chains with cellular connections 7. Cells solitary, or united by slime threads or masses 17.

7 Cells joined by ring of spines 8. Cells joined by portion of valves 9. 8 Valves markedly areolate Stephanopyxis. Valve structure difficult to see Skeletonema. 9. Height of cell not more than 1½ times breadth 10. Height of cell more than 1½ times breadth 12. 10. Each half of frustule with circular intercalary band Bacterosira. No intercalary bands 11. 11. Sculpture very marked, keel-shaped depression at margin Melosira (Paralia) Sculpture not marked, no marginal depression Melosira 12. Cells joined by two flat processes at margin Cerataulina. Cells joined by centre or whole of valve surface 13 13. Cells joined by single excentric spine fitting into a groove in adjacent cell Rhizosolena Cells without spines, but may have marginal spinules 14. 14. Cells with ring of marginal spinules Detonula Cells without marginal spines 15. 15. Intercalary bands absent Leptocylindrus. Intercalary bands numerous 16. 16. Intercalary bands imbricate Dactyliosolen. Intercalary bands collar-like Guinardia. 17. Cells united by a slime thread or embedded in mass of slime 18. Cells usually solitary 20. 18. Cells with 1 circular intercalary band 19. Cells with several intercalary bands Lauderia. 19. Cells united by several sub-central threads Coscinosira Cells united by single central thread or in slime mass Thalassiosira 20. Cells elongate-cylindrical, height exceeds diameter 21. Cells drum-shaped or discod, height less than diameter 24. Cells almost spherical Pyxidicula. 21. Valves with excentric spine or bristle Rhizosolenia. Valves with central spine Ditylum Valves without spines 22. 22 Valves with 2 short marginal processes Cerabaulina. No processes 23. 23. Intercalary bands imbricate Dactyliosolen. Intercalary bands circular Guinardia. 24. Cells surrounded by chambered, hyaline wing Planktoniella. No hyaline wing 25. 25. Cells zygomorphic, with excentric, stellate thickening Asteromphalus. Cells circular in valve view 26. 26. Valves radially undulate, with raised and depressed sectors 27. Valves not obviously undulate 28. 27. Raised and domed central area Aulacodiscus Central area not raised and domed Actinoptychus 28 Valves with 1 or more marginal processes (ocelli) 29. No marginal ocelli 30. 29. Valves punctate, with short radial hyaline interspeces Cosmiodiscus. Valves radially divided by hyaline interspeces Stephanodiscus. Valves divided into sectors by costae Arachnoidiscus. Valves radially punctate, not divided into sectors Actinocyclus. Valves punctate, striate, zygomorphic, relative to ocelli Auliscus 30. Central area evident 31 Central area absent, rosette may be present Coscinodiscus. 31. Central area markedly divided into cunieform segments Asterolampra. Central area not so divided, puncta uniform Hyalodiscus. 32. Valve margin semicircular Hemidiscus Valve margin not semicircular 33. 33. Valve margin triangular to polygonal 34 Valve margin not triangular, but usually with bilateral symmetry 38 34. Cells with central spine 35 Cells with 2 or more excentric spines or spineless 36. 35. Cells solitary or in pairs Ditylum. Cells in chains attached by valve margins Lithodesmium 36. Frustules heavily silicified, structure obvious Triceratium. Frustules lightly silicified, structure not marked 37.

Fig. 1 Melosua moniliforms. 2 M. sulcata, (a) girdle view (b, c) valve view, 3. M. nummuloides 4 M. yurgensu 5 Hyalodiscus stelliger 6 Coscinodiscus concinnus 7, C. Centralis 8, C. gigas 9 C. marginatus 10 C. excentricus. 11. C. concavus. 12, C. radiatus 13. C. granulosus, 14 C. curcatulus 15 C. lineatus 16 Pyridicula cruciata, (a) median girdle view (b) girdle view. showing areolae (c) valve view 17 Charcotia bifrons

Fig. 18, Planktomella sol, 19, Actinoptychus senarius 20. A adriaticus, 21, A splendens 22, Aulacodiscus beeveriae, 23, Aul margaritaceus, (a) whole valve, (b) central area, showing areolation, 24, Auliscus sculptus, 25, Biddulphia thumn 26 Asterolampra marylandica. 27 Astermophalus hooken, 28, Cerataulina chapmann n. sp. (a) girdle view, (b) valve view showing twisting on pervalvar axis, 29a and b, Biddulphia sansibanca, 54. Gossleriella tropica

Fig. 30. Biddulphia chinensus 31. B. turgida. 32 B. pulchella 33, B. aurita 34 B. reticulata, (a) girdle view, (b) valve view 35 Triceratium favus 36 T. robertsianum, (a) valve view (b) girdle view. 37 T. alternans 38. T. pentacrinum (pentagonal form) 39. T. pardus 40 a and b T. dubium 41 T. tessellatum 42 T. remculum

Fig. 43 Isthmia nervosa 44 I. enervis 45 a and b Belierochea malleus 46 Eucampia bataustium, 47, Chaetoceros concolutum. 48. Ch messanense 49, Ch crrophilum, 50, Ch schimperianum 51 Rhizosolema hebetata, 52 R. styliformis 53 Hemidiscus cunieforms, 4a, Melosura jurgensu, showing change in cell size

Fig. 1. Hyalodiscus stelliger, girdle view 2 Stephanopyxis palmeriana, 3, S. turris. 4, Skeletonema costatum. 5 Detonula confervacea 6 Thalassiosira rotula, 7. T. gravida 8 T. condensata, 9, T. baltica, 10, T. aestivalis, 11, T. subtilis 12 T. hyalina, 13 T. decipiens, 14 Lauderia annualata, 15 Schroederella delicatula

Fig. 16, Coscinodiscus concinnus, girdle view 17, C. granu, girdle view, 18, Cerataulina pelagica, 19, Biddulphia mobiliensis, 20, B. dubia 21, B. regia, 22, Lithodesmium undulatum 23, Hemiaulus haucku, 24, H. sinensis, 25, H. membranaceus, 26, H. indicus, 27, Ditylum brightwellu, 28, Eucampia zoodiacus, 29, Eucampia cornuta, 30, Climacodium frauenfeldianum, 31, Cl bioconcavum, 32, Streptotheca thamesis, 33, Streptotheca indica, 34, Chaetoceros affine 35. Ch atlanticum, (a) var typica, (b) var audax, (c) var neapolitana, 36, Ch. castracanet

Fig. 37, Ch cinctum, 38. Ch coarctatum 39 Ch compressum, 40, Ch concavicorne 41 Ch secundum 42, Ch danicum, 43. Ch debile. 44, Ch decipiens, 45, Ch denticulatum 46, Ch diadema, 47, Ch dichaeta, 48, Ch difficule 49 Ch eibenn 50, Ch laciniosum. 51 Ch lauden

Fig. 52, Chaetoceros lorenzianum, 53, Ch mitra, 54, Ch paradoxum, 55, Ch rostratum, 56 Ch simile, 57 Ch sociale, 58, Ch teres, 59, Ch vanheurcku, 60, Bacteriastrum varians, 61 B. delicatula, 62. Rhizosolenia alata, (a) var typica, (b) f gracillima, (c) f indica, (d) f inermis, 63 R. acuminata, 64, R. bergonu, 65, R. calcar-avis. 66, R. castracanei. 67 R. chunu 68. R. clever 69 R. curvata 70. R. cylindrus

Fig. 71, R. delicatula 72. R. fragilissima 73 R. hebetata, (a) f hiemalis, (b) f spimfera 74, R. imbricata, (a) var typica, (b) var shrubsoler, 75, R. robusta, 76 R. setigera, 77 R. stolterforthu, 78 a and b R. styliforms, 79 Guinardia flaccida, 80, Leptocylindrus damicus 81, Dactyliosolen mediterianeus, 82, D. antarcticum, 83, Corethron cirophilum

37. Chains twisted on chain axis Streptotheca. Chains not twisted Bellerochea. 38. Valves with single, excentric spine Rhizosolenia No single excentric spine 39. 39 Poles on longitudinal axis dissimilar 40. Poles on longitudinal axis similar 42. 40. Planktonic, in spiral or stellate chains, cells hammer-shaped Asterionella. Planktonic, solitary Synedra. Epontic or at least stipitate, cuneate 41. 41. No raphe; foramina obvious and characteristic Climacosphenia No raphe or foramina, valves transversely costate Podocystis. No raphe or foramina, valves not transversely costate Licmophora. Raphe on lower valve, pseudoraphe on upper Rhotcosphenia Raphe on both valves Gomphonema. 42. Both valves with processes or protruding corners 43. No processes or protruding corners 52. 43. Processes ending in long spines Chaetoceros. Processes without spines 44. 44. Cells in chains, straight or twisted, never zig-zag 45. Cells solitary or in zig-zag chains 49. 45 Chains spirally twisted 46. Chains straight 47. 46. Chains twisted about apical axis, processes pointed Hemiaulus. Chains twisted about transapical axis, process blunt Eucampia. 47. Cells united by centre and marginal processes Bellerochea. Cells united by 2 marginal processes only 48. 48. Cells cylindrical or nearly so Cerataulina Cells flattened Climacodium. 49. Cells strongly twisted about pervalvar axis Biddulphia. Cells not twisted about pervalvar axis 50. 50. Cells twisted about longitudinal axis Hemiaulus. Cells not twisted 51. 51 Valves cuneate in girdle view Isthmia. Valves not cuneate in girdle view Biddulphia. 52 Cells form compact, stiff, ribbon-like chains 53. Cells solitary or colonial, not in ribbons 54. 53. Chains twisted longitudinally, chromatophores numerous Streptotheca. Chains not normally twisted, chromatophores 1–2 per cell 54. 54 No raphe 55. Raphe incomplete Eunotia. Raphe on at least 1 valve 60. 55. Longitudinal axis 10 times or more transverse axis Synedra Longitudinal axis normally less than 10 times transverse axis 56. 56. Frustules septate 57. Frustules not septate 59. 57. Septa numerous 58 Septa 2, sinuate Grammatophora Septa, 2–6, straight Tabellaria. Septa alternate Striatella 58. Foramina present in septa Rhabdonema No foramina in septa Terpsinoe 59. Valves transverse costate Plagiogramma. Valves radially costate Omphalopsis. Valves not costate 71. 60. Raphe on only one valve 61. Raphe on both valves 62. 61 Cells stipitate in chains, bent along longitudinal axis Achnanthes. Cells not stipitate, often in gelatinous sheath, not bent Cocconeis. 62 Valves asymmetrical on longitudinal axis 63. Valves symmetrical 66. 63. Keel present 64. No keel 75. 64. Valves twisted Amphiprora. Valves sigmoid 65. 65. Raphe median, sigmoid Pleurosigma. Raphe marginal Nitzschia.

66. Cells solitary, saddle-shaped Campylodiscus. Cells not saddle-shaped 67. 67. Keel present 69. No keel 68. 68. Striae of valve punctate and alveolate in 3 strata Trachyneis. Striae interrupted by blank lines 72. Striae punctate and costate, median line with horns Diploneis. Striae punctate, valves separated by septate plates Diatomella. Striae punctate, valves with marginal loculi Mastogloia. Striae costate, not punctate Pinnularia Striae punctate, no marginal loculi or septate plates 73 69. Keels borne on alae Surirella. Keels not on alae 70 70. Keels central Bacillaria. Keels excentric opposite Hantzschia. Keels excentric, not opposite Nitzschia 71. Pseudoraphe present Fragilaria. No pseudoraphe Fragilariopsis. 72. Median pores in opposite directions Neidium. Median pores not in opposite directions, longitudinal lines near border Caloneis. Median pores not in opposite directions, striae interrupted by longitudinal areas Anomoeoneis. 73. Central area with stauros Stauroneis. Central area without stauros 74. 74. Central nodule drawn out over half length of valve Amphipleura. Central nodule slightly elongated Frustulia. Central nodule not drawn out Navicula 75. Raphe approximating to ventral margin Amphora. Raphe asymmetrical 76 Raphe approximating to dorsal margin Rhopalodia. 76. Internal septa present Epithemia. No internal septa Cymbella The Diatom Species Sub-order Discineae Family Coscinodiscaceae Genus Melosira Agh., 1824 Cells occurring in chains, usually with a mucous cushion or threads at junction of cells; free or epontic; frustules discoid to cylindrical, apices may be rounded; surface punctate or areolate, intercalary bands numerous. Key to Species of Melosira 1 Cells discoid M. sulcata. Cells cylindrical, with hemispherical valves 2. 2 Cells with annular keel M. nummuloides. No annular keel 3 3. Frustules constricted under girdle sheath M. jurgensii. Frustules not constricted M. moniliformis 1. Melosira moniliformis (Müller) Agh. (Plate 31, Fig. 1). Agh., 1824, 8; Hustedt, 1927, 236, 98; Hendey, 1951, 31. Melosira borreri Grev., in Hooker, 1833, 401. Conferva moniliformis Müller, 1783, 3, 1–5 in Agh., 1830, 65. Cells usually in long chains; frustules short, cylindrical, two or three times longer than broad; valves cylindrical with hemispherical apices, surface finely punctate; girdle punctate with numerous fine annuli; two size-groups may occur in one chain. Length 30–70, breadth 20–40μ. Distribution. Estuarine-neritic, benthic and sometimes planktonic, occurring in algal and Zostera washings, mud, on rocks and in fish stomachs. Australia: Moreton Bay, Port Hacking, Ulladulla, Eden, Port Phillip. New Zealand: fossil in Oamaru (Grove & Sturt, 1887), also in Weber Deep at 9,000 m †.

2. Melosira sulcata (Ehr.) Kütz. (Plate 31, Figs. 2a, b, c). Kütz., 1844, 55, 2, 7; Boyer, 1927, 25; Hendey, 1951, 30. Gallionella sulcata Ehr., 1840, 3, 5. Paralia sulcata (Ehr.) Cl., 1873, 7. Paralia sulcata Ehr. in Lebour, 1930, 28, 9. Cells usually in short chains; frustules thick-walled, discoid, with robust margin and coarsely granulate surface; valve view discoid with short striae converging towards hyaline centre; girdle with series of coarse areolae giving a window-like appearance; in these areolae, a secondary series of hexagonal areolae can be seen. Diameter 20–40μ. Distribution. Estuarine-neritic; in mud, sand, on sea grasses, fouling test plates and in plankton. Australia: in coastal plankton to 50 miles offshore from Moreton Bay to Jervis Bay, and in estuaries, Moreton Bay, Clarence River, Port Jackson, Botany Bay, Port Hacking, western Bass Strait. New Zealand: Auckland Harbour, also Foveaux Strait, Lyall Bay, Campbell Island (Petit, 1877), Oamaru (Gr. & St., 1887). 3. Melosira nummuloides (Dillwyn) Agh. (Plate 31, Fig. 3). Agh., 1824, 8. Boyer, 1927, 26. Hendey, 1951, 31. Cells usually in long chains; frustules spherical with flattened extremities; valves hemispherical, flattened at cell junctions, faintly punctate, not constricted in valve mantle, annular keel just below valve apex. Diameter 15–25μ. Distribution. Estuarine, sometimes in neritic plankton; euryhaline: from seaweed, Zostera, muds, rocks and fouling test plates. Australia: Moreton Bay, Lake Macquarie, Port Jackson, Port Phillip. New Zealand: Auckland Harbour. 4. Melosira jurgensii Agh. (Plate 31, Fig. 4). Agh., 1824, 9. Ralfs in Pritch., 1861, 817. Schönfeldt, 1907, 72. Boyer, 1927, 27. Cells usually in chains; frustules cylindrical, slightly constricted under girdle sheath; valves convex, finely punctate, appearing hyaline. Diam. 20–30μ. Distribution. Epontic, euryhaline. Australia: (østrup, 1910), Botany Bay, Port Hacking, Lake Macquarie. New Zealand: Wellington Harbour. The following additional species have been recorded by previous authors:– M. architecturalis Brun, 1891. (A. S., 1892, 175, 45–46.) Oamaru. M. clavigera Grun. in vH., 1885. (A.S., 1892, 175, 21; Gr. & St., 1887, 66). Oamaru. M. clypeus Brun, 1891. (A. S., 1892, 179, 2, 3.) Oamaru. M. distans (Ehr.) Kütz., 1844. (Ehr., 1869; Boyer, 1927, 30.) Australia. M. exspectata A.S. (A. S., 1892, 177, 54–58.) Oamaru. M. italica (Ehr.) Kütz., 1844. (Ralfs in Pritch., 1861, 818.) Australia. M. laevis? (M. roseans Rab., 1853.) (Ralfs in Pritch., 1861, 818; Ehr., 1869.). Australia. M. major Grove in A. S. (A. S., 1892, 177, 1.) Oamaru. M. oamaruensis Gr. & St., 1887. (A. S., 1892, 175, 1–4.) Oamaru. M. pontificalis Brun, 1891. (A. S., 1892, 183, 1.) Oamaru. M. praeclara A. S. (A. S., 1892, 179, 4.) Oamaru. M. saturnalis Brun, 1891. (A. S., 1892, 180, 24.) Oamaru. M. sol (Ehr.) Kütz., 1844. (Gr. & St., 1887, 66.) Oamaru. M. truncata Grev. in Hooker, 1833 (is M. moniliformis Agh.). M. westii W. Sm., 1856. (Gr. & St., 1887, 66.) Oamaru. A number of unidentifiable species were described as Gallionella spp. by Ehr., 1869. Genus Hyalodiscus Ehr., 1845 Cells solitary or in short chains, cylindrical to drum-shaped; valves rounded, finely punctate, puncta radial; central area differentiated. May be planktonic or attached by a mucous cushion.

5. Hyalodiscus stelliger Bail. (Plate 35, Fig. 1; Plate 31, Fig. 5). Bail., 1855, 10, 11. Lebour, 1930, 30, 10. Valves strongly curved, marked with fine moniliform striae; central area strongly differentiated, peripheral zone striate, striae often parallel; intercalary bands narrow. Diameter, 50μ. Distribution. Planktonic, Australia: S.E. coast. New Zealand: Lyall Bay (Petit, 1877). Auckland Harbour. The following species have been recorded by previous authors: H. arcticus Cl. in Cl. & Grun., 1880. (Gr. & St., 1887, 67.) Oamaru. H. coralla (Podosira coralla) A. S. (A. S., 1891, 140, 11, 12.) Oamaru. H. hormoides Kütz., 1844. (Petit, 1877, 14; Gr. & St., 1887, 67.) Lyall Bay, Oamaru. H. laevis Ehr.? var. yarrensis Grun. in Cl. & Grun., 1880. (Cl. & Grun., 1880.) Yarra deposit. H. maculatus W. Sm., 1856. (Petit, 1877, 14.) Lyall Bay. H. maximus Petit. (Petit, 1877, 15; Gr. & St., 1887, 67.) Campbell Island, Oamaru. H. punctatus A. S. (A. S., 1886, 139, 16.) Oamaru. H. radiatus (O'Meara) Grun. in Cl. & Grun., 1880. (Gr. & St., 1887, 67.) Oamaru. H. scoticus (Kütz.) Grun. in v H., 1885. (østrup, 1910.) Australia. H. subtilis Bail., 1855. (Gr. & St., 1887, 67; Petit, 1877, 15.) Campbell Island, Oamaru. H. valens A. S. (A. S., 1886, 140, 1.) Oamaru. Genus Stephanopyxis Ehr., 1844. Cells in chains, frustules globoid or cylindrical with hemispherical or cup-shaped valves and cytoplasmic connections between the cells through stout, hollow, articulated spines more or less parallel with pervalvar axis; valves areolate, intercalary bands absent; chromatophores small, round, numerous. Key to Species of Stephanopyxis Areolae decreasing in size towards girdle S. palmeriana. Areolae more or less uniform S. turris. 6. Stephanopyxis palmeriana (Grev.) Grun. (Plate 35, Fig. 2). Grun., 1884, 90. Gran and Angst, 1931, 431, 6. Creswellia palmeriana Grev., 1865, 2. S. campana Castr., 1886, 68. Cells in chains; frustules cylindrical with rounded ends, areolate; areolae decreasing in size towards girdle line. Diameter, 60–80μ. Distribution. Planktonic, oceanic. Australia: East coast, Thursday Island to Moreton Bay, in June; Moreton Bay to Babel Island, winter through to summer; Shark Bay (Grev., 1865). 7. Stephanopyxis turris (Grev. & Arnott) Ralfs (Plate 35, Fig. 4). Ralfs, in Pritch., 1861, 826. Creswellia turris Grev. & Arn., 1857, 109, 14. Pyxidicula appendiculata Ehr., 1844, 18, 4. Creswellia turgida Grev., 1859, 165. Steph. cylindrica Ehr., 1873, 214. S. niejahri Ehr., 1873, 2, 1. S. turgida (Grev) Ralfs in Pritch., 1861, 826. Cells in chains; frustules cylindrical with strongly convex ends, areolate; areolae not diminished near girdle line. Diameter, 40–50μ. Distribution. Australia: East coast, Thursday Island; Port Stephens to Babel Island; no record from South or Western Australia; indicator of East Australian current. New Zealand: East coast; also from Oamaru (Gr. & St., 1887, 70).

Also recorded from Oamaru by Grove and Sturt, 1887, are: S. barbadensis (Grev.) Grun., 1884. S. ferox (Grev.) Grun., 1884. Genus Skeletonema Grev., 1865 Cells spherical, lenticular or cylindrical, in chains; frustules without distinct sculpture; row of spines at valve margin parallel to longitudinal axis joining cells into chains by interlocking. 8. Skeletonema costatum (Grev.) Cl. (Plate 35, Fig. 4). Cl. 1878, 18. Allen and Cupp, 1935, 113, 3. Melosira costata Grev. 1866, 8, 3–6. Chains thin, usually straight; cells lenticular to cylindrical; space between cells usually longer than cells. Diameter 4–6μ. Distribution: Estuarine-neritic; an important food form for barnacle and other crustacean larvae; mainly in spring to autumn. Recorded from Java Sea by Allen and Cupp. Australia: Cape Byron to St. Helens and in Lake Macquarie, on east coast; Port Phillip (Victoria) and Swan River (West Australia). New Zealand: Wellington Harbour. Genus Detonula Schütt, 1893 Cells cylindrical, united in straight or curved chains; frustules cylindrical; valves with a single row of marginal spinules, but without unpaired apicule; several intercalary bands; chromatophores numerous. 9. Detonula confervacea (Cl.) Gran (Plate 35, Fig. 5). Gran, 1900, 113. non D. cystifera Lebour, 1930, 75. Lauderia confervacea Cl., 1896, 11, 2, 21. Cells in long, thin chains, forming bundles; frustules with small, marginal spinules; walls thin; inconspicuous intercalary bands. Diameter, 10μ. Distribution. Oceanic, winter; a tropical form associated with the Coral Sea water mass. Australia: East coast from Sandy Cape to Montague Island. Genus Thalassiosira Cl., 1873 Cells drum-shaped, united in flexible chains by a cytoplasmic thread; occasionally solitary or embedded in an amorphous, gelatinous mass; valves flat, sometimes depressed centrally; delicately punctate; marginal spinules present; intercalary bands present; chromatophores numerous, flat; fat globules usually present. Key to the Species of Thalassiosira 1. Cells in a gelatinous matrix 2. Cells connected by a single thread 3. 2. Large gelatinous masses containing numerous small (15μ) cells T. subtilis. A few larger (20μ) cells in small gelatinous colonies with thread T. decipiens. 3. Cells in straight or slightly curved, rather stiff chains 4. Cells in loose flexuous chains 6. 4. Surface structure obscure T. gravida. Surface structure not obscure 5. 5. Intercalary bands unevenly thickened T. rotula. Intercalary bands evenly thickened T. hyalina. 6. Valve sculpture radial T. baltica. Valve structure not apparent T. condensata. Valves finely areolate T. aestivalis. Valves with excentric areolae T. decipiens. 10. Thalassiosira rotula Meunier (Plate 35, Fig. 6). Meunier, 1910, 264. Boden, 1950, 335, 7. Cells discoid, united in chains by a thick thread; frustules flat, valves with slightly rounded margins; puncta delicate; intercalary bands unevenly thickened. Diameter, 50μ.

Distribution. Neritic. Australia: Jibbon Cape to Eden; Port Phillip; recorded from April to September, with a maximum in August. New Zealand: East Cape. 11. Thalassiosira gravida Cl. (Plate 35, Fig. 7). Cl., 1896, 31, 2, 5a. Lebour, 1930, 59. Cells discoid, united by a thick thread; frustules rectangular in girdle view, with slightly rounded margins; margins with one spine and numerous small spinules; valve structure faint; intercalary bands evenly thickened. Diameter, 30μ. Distribution. Off Cape Byron. Rare. 12. Thalassiosira condensata Cl. (Plate 35, Fig. 8). Cl., 1900a, 88, 8, 12–13. Boden, 1950, 335, 8. Cells united by a central thread of varying length, usually short; frustules in girdle view rectangular or square, centre of valve depressed; one row of marginal spinulae; intercalary bands numerous; sculpture not apparent. Diameter, 30μ Distribution. Neritic. Australia: Trial Bay to Port Hacking in summer; Port Phillip. New Zealand: Hauraki Gulf. 13. Thalassiosira baltica (Grun.) Ost. (Plate 35, Fig. 9). Ost., 1901, 290, 3. Lebour, 1930, 61, 33. Coscinodiscus polyacanthus v. baltica Grun. in Cl. and Grun., 1880, 112. Coscinodiscus balticus Cl., 1891, 68. Cells discoid, united by thin threads into loose chains; frustules in girdle view rectangular with rounded margins; a few short marginal spinules; valve sculpture radiate, punctate. Diameter, 35μ. Distribution. Oceanic. Australia: Trial Bay, Campden Haven, Port Stephens, Montague Island, Eden, Babel Island, St. Helens. An East Australian current form. 14. Thalassiosira aestivalis Gran (Plate 35, Fig. 10). In Gran and Angst, 1931, 436, 10. Cells rectangular in girdle view, connected by a thread, solitary in older cultures; valves flat with slightly depressed central area, finely areolate; margin with long spinules; intercalary bands evident. Diameter, 25μ. Distribution: Estuarine. Sea water tank, Marine Lab. Port Hacking, autumn, 1956; Jibbon Cape, spring, 1956. 15. Thalassiosira subtilis (Ost.) Gran (Plate 35, Fig. 11). Gran 1900, 117. Boden, 1950, 337, 9. Podosira (?) subtilis Ost., 1899, 55. Cells drum-shaped, embedded in a gelatinous matrix; intercalary bands numerous; no distinct sculpture. Diameter, 15μ. Distribution. Australia: Trial Bay to St. Helens; rare in eastern Bass Strait; spring form. Found in gut of cyprid larvae in Port Jackson. East Australian current indicator. New Zealand: North-east coast. 16. Thalassiosira hyalina (Grun.) Gran (Plate 35, Fig. 12). Gran, 1897, 4, 1, 17–18. Boden, 1950, 337, 10. Coscinodiscus hyalinus Grun. in Cl. and Grun., 1880, 113, 7, 128. T. clevei Gran, 1897, 29, 4, 60–62. Cells discoid, united in chains at irregular intervals by a central thread; frustules slightly rounded at margins, with a single marginal spine and small spinules; surface with fine radial striae. Diameter 40μ. Distribution. Australia: Shoalhaven, November, 1938. New Zealand: Hauraki Gulf, Wellington. 17. Thalassiosira decipiens (Grun.) Jörgensen (Plate 35, Fig. 13). Jörg., 1905, 96, 6, 3. Grun., 1878, 125, 4, 18, as Coscinodiscus excentricus var. (?) decipiens. Coscinodiscus decipiens Grun. in von H., 1880–1885, 91, 10.

Cells drum-shaped, in loose chains with long threads and occasionally in gelatinous colonies or single; valves flat or slightly curved, with rounded margins; spine and small strong spinules, surface with excentric areolae resembling Coscinodiscus excentricus. Diameter, 20μ. Distribution. Neritic. Australia: South-east coast, in 1957. Cultivated from plankton. Genus Lauderia Cl., 1873 Cells drum-shaped, united in chains by slimy threads of adjacent valves with unpaired apicule and numerous very small spinulae over valve surface to margin; intercalary bands numerous; chromatophores numerous. 18. Lauderia annulata Cl. (Plate 35, Fig. 14). Cl., 1873a, 11. Allen and Cupp, 1935, 124. Cells drum-shaped, in chains; valves slightly convex with a slight central depression, elevated portion usually touching adjacent cell; valves spinulate; intercalary bands numerous; surface delicately punctate. Diameter 30μ. Distribution. Oceanic to neritic. Australia: Sandy Cape to Maria Island, May to September; Fremantle, Rottnest. New Zealand: Hauraki Gulf and south of New Zealand (57° S.). Genus Schroederella Pav., 1913 Cells cylindrical, forming straight chains, sometimes solitary; valves flat or slightly convex, depressed in centre; distinct, central spine uniting cells; margin surrounded by a row of small spinules from which arise two gelatinous threads which diverge and unite with corresponding threads from adjacent cell, forming a characteristic herring-bone effect, intercalary bands numerous. 19. Schroederella delicatula (Perag.) Pav. (Plate 35, Fig. 15). Pav., 1913, 126. Lauderia delicatula Perag., 1888, 81. Detonula delicatula Gran, 1900, 112. Detonula schroederi Gran, 1905, 22. Lauderia schroederi Bergon, 1903, 69. Schroederella schroederi (Bergon) Pavd, 1925, 23. Cells cylindrical, united in rigid chains; valves convex or flat, depressed in centre; intercalary bands numerous; valve surface delicately areolate. Diameter, 25μ. Distribution. Oceanic. Australia: Rare north of Moreton Bay, common from Cape Byron to Eden from May to September; an East Australian current indicator on the east coast; also recorded from off Lakes Entrance and west of Bass Strait (Victoria), Spencer Gulf, Swan River. New Zealand: Hauraki Gulf, Milford Sound. Genus Coscinodiscus Ehr., 1838 Cells simple discs, without large knobs or processes; single, valve sculpture areolae, puncta or striations arranged in various ways; marginal spinules may be present; girdle a single band with one or more intercalary bands. Key to the Species of Coscinodiscus 1. Cells in girdle view cuneate C. granu Cells in girdle view drum-shaped, depth more than half diameter, valves domed C. concinnus. Cells discoid, depth less than half diameter 2. 2. Central area present C. gigas No central area 3 3. Margin striate 4. Margin not striate 5. 4. Centre irregularly and heavily punctate C. granulosus. Centre hexagonally areolate C. marginatus. 5 Central rosette present 6. No central rosette 7. 6 Meshes decreasing from centre to margin C. centralis. Meshes not so decreasing C. concinnus 7. Areolae excentric in slightly curved rows C. excentricus. Areolae excentric in straight rows C. lineatus. Areolae in fascicules of curved lines, one line of each fasicule running from centre to margin C. curvatulus. Areolae irregular in centre, somewhat concentric near margin C. concavus.

20. Coscinodiscus concinnus W. Sm. (Plate 36, Fig. 16, Plate 31, Fig. 6). W. Sm., 1856, 85. Gran and Angst, 1931, 447, 25. Cells large, drum-shaped, with convex valves, which may be slightly indented centrally; walls thin, hyaline, with fine radial sculpture, typically with a rosette of large meshes, but this may be replaced by a large central area; radial rows and spiral secondary rows regular; spinules inside margin, from which more or less distinct, hyaline ribs run to centre; two small spines present at an angle of about 120°; girdle with many intercalary bands. Diameter, 200–500μ. Distribution. Estuarine. Australia: Thursday Island, Lake Macquarie, Port Jackson, Botany Bay, Port Hacking, Eden, from March to June; Lakes Entrance, Port Phillip in June. New Zealand: East of Norfolk Island, Auckland Harbour; from Oamaru (fossil) as C. oamaruensis (Gr. & St., 1887). var. jonesianus (Grev.) Rattray. Ratt., 1890, 84, 7. Eupodiscus jonestanus Grev., 1862, 22, 2, 3. C. jonestanus Ost., 1915, 13, 7. Allen & Cupp, 1935, 116, 10. Cells large, solitary; valves flat or concave in centre, sometimes slightly higher on one side than on the other; rosette usual but may be absent; areolae becoming smaller from centre to margin; radial and secondary spiral rows regular; interstitial meshes, probably spinules, sometimes present, forming an irregular ring about half-way between margin and centre; marginal spinules with radial ribs from these towards centre; two large, conical processes near margin at about 120°. Diameter, 200–400μ. Distribution: Australia: Port Stephens, Maria Island, St. Helens; rare. 21. Coscinodiscus centralis Ehr. (Plate 31, Fig. 7). Ehr., 1839, 129. Lebour, 1930, 39, 16. Cells solitary, discoid; valves convex, not flattened centrally; sculpture strong, radial with central rosette, meshes decrease in size from centre; marginal spinules small; two asymmetric spines, girdle with several intercalary bands. Diameter, 80–250μ. Distribution. The species is largely estuarine in Australian waters and oceanic and estuarine in New Zealand waters. Australia: Moreton Bay, Clarence River, Lake Macquarie, Port Jackson, Botany Bay, Port Hacking, Eden, Gordon (Tasmania). New Zealand: Auckland Harbour (N.Z.), and south to 42° S., 180° W. Fossil by Gr. & St., 1887, from Oamaru. Mindanao deep to 9,000 m. var. pacifica Gran and Angst (Plate 31, Fig. 7). Gran and Angst, 1931, 446, 23. Differs from the type by having a flattened central portion of valve, indistinct, radiating lines on valve, and by a broader marginal zone outside the spinules. Diameter, 100–200μ. Distribution. Australia: East coast phytoplankton. 22. Coscinodiscus gigas Ehr. (Plate 31, Fig. 8, a and b). Ehr., 1840, 412. Allen and Cupp, 1935, 120, 16. Cells discoid, with almost flat valves; no central rosette, central area large; areolae near margin small, then large and dark, becoming more delicate and hyaline towards centre; radial rows and secondary spiral rows very regular; two asymmetric processes at about 120°. Diameter, 300–550μ. Distribution. Australia: Jibbon Cape, Jervis Bay, July; Gordon (Tasmania), June; East Tasman Seas. New Zealand: Hauraki Gulf, Port Fitzroy (as dominant). 23. Coscinodiscus marginatus Ehr. (Plate 31, Fig. 9). Ehr., 1841, 142. Allen and Cupp, 1935, 115, 7. C. subconcavus Grun., f. major A. S., 1875, 62, 7. Cells solitary, thick walled; valves convex with large areolae in more or less radial or parallel rows; no central area or rosette; areolae smaller at margin, which is heavily striate Diameter 40–100μ. Distribution. Australia: Cape Byron, Moreton Bay, St. Vincent Gulf. New Zealand: Tasman Sea, east of Norfolk Island, and Milford Sound. Common in.

Galathea muds from Mindanao, Soenda and Weber Deeps, Solomon Islands. Hendey (1937) remarks that this is a bottom form, and this is obviously true, though the species is not confined to shallow water or to the continental shelf. 24. Coscinodiscus granii Gough (Plate 36, Fig. 17). Gough, 1905, 338. Hendey, 1937, 246, 3, 2. Cells discoid in valve view, cunieform in girdle view; valves with central rosette, finely areolate; areolae in radial lines, large at centre, decreasing to margin; margin with fine spinules, from which fine, hyaline lines proceed to centre of valve; girdle cuneate, valve excentric. Diameter, 200–500μ. Distribution. Estuarine-neritic. Australia: Moreton Bay in June, Clarence River, Lake Macquarie, Port Jackson, Port Hacking, Eden from May to August, Port Phillip from April to September. New Zealand: Auckland Harbour, February. Often in blooms on the east coast of Australia associated with blooms of Rhizosolenia. 25. Coscinodiscus excentricus Ehr. (Plate 31, Fig. 10). Ehr., 1840, 146. Cupp, 1943, 52, 14, 1, 1. C. subconcavus Grun. f. major A. S., 1875, 62, 7. Cells simple discs; valves flat with narrow margins, having spinules in an irregular circle; areolae in slightly curved, nearly parallel rows based on an arrangement of 7; meshes not radiating from centre; usually a single, central mesh with 7 meshes surrounding it. Diameter, 100μ. Distribution. Australia: Lake Macquarie. New Zealand: Frequent in plankton between Norfolk Island and Auckland; Campbell Islands (Petit, 1877), Oamaru (Gr. & St., 1887). 26. Coscinodiscus concavus Greg. (Plate 31, Fig. 11). Greg., 1857, 31, 500. Boyer, 1927, 45. Cells solitary; valves nearly flat; central space absent, markings angular, of constant size, irregular in centre but somewhat concentric near border; border rugose, with coarse striae. Diameter, 50–100μ. Distribution. Australia: Port Hacking. New Zealand: Fossil from Oamaru (Gr. & St., 1887). 27. Coscinodiscus radiatus Ehr. (Plate 31, Fig. 12). Ehr., 1840, 148, 3, 1. Hendey, 1937, 250. Cells discoid, solitary, without spinules; valves flat, with polygonal areolae and no central rosette; areolae smaller at margin; girdle narrow, striate; chromatophores numerous. Diameter, 70–150μ. Distribution. Australia: Gunnamatta Bay, Port Hacking, and offshore; infrequent. New Zealand: Lyall Bay, Campbell Island (Petit, 1877), and fossil from Oamaru (Gr. & St., 1887). 28. Coscinodiscus (Odontodiscus) granulosus Grun. (Plate 31, Fig. 13). Grun. in Cl. and Grun., 1880, 113, 7, 130. Cells small, solitary; valve with a delicately striate, strongly marked, narrow margin and an irregularly but heavily punctate convex centre, the perimeter of the centre has a crowd of heavier puncta (spinules) which are not always equally evident. Diameter 15–40μ. Distribution. Antarctic, south of New Zealand to 57° S. Previously described from Finland, Seychelles and the Adriatic, by Grunow. 29. Coscinodiscus curvatulus Grun. (Plate 31, Fig. 14). Grun. in A. S., 1876, 57, 33. Hendey, 1937, 251. C. rothii Manguin, 1954. Cells discoid, solitary valves almost flat, coarsely areolate; areolae in fasicules of curved lines, one line of each fasicule running from centre to margin, rest shorter; areolae polygonal, maximum size half way between centre and margin of valve; margin with short radial striae; no central area or rosette. Diameter, 70μ. Distribution. New Zealand: Auckland Harbour; rare in eastern Tasman off New Plymouth. 30. Coscinodiscus lineatus Ehr. (Plate 31, Fig. 15). Ehr., 1838, 129, 37; Boden, 1950, 341, 14. Cells discoid; valves flat, with hexagonal areolae, smaller near margin; differs from C. excentricus in that areolae are in straight lines at about 60°. Diameter, 30–50μ.

Distribution. Australia: Bass Strait. New Zealand: Foveaux Strait, Lyall Bay (Petit, 1877). The following species of Coscinodiscus have been recorded previously from this region:– C. angulatus Grev., 1864. (Gr. & St., 1887.) Oamaru. C. argus Gr. & St. (Gr. & St., 1887.) Oamaru. C. bulliens A. S., 1875, 61 (Gr. & St., 1887.) Oamaru. C. conclusus Grun. in A. S., 1886. (A. S., 1890, 63.) Oamaru. C. decrescens Grun., 1884. (Gr. & St., 1887.) Oamaru. C. elegans Grev., 1866. (Gr. & St., 1887.) Oamaru. v. inermis Pant., 1886. (A. S., 1899, 229, 1.) Oamaru. C. fasciculatus A. S., 1874, 57, 9–10 (Petit, 1877). Lyall Bay. C. galapagensis Ratt., 1880. (A. S., 1890, 163.) Oamaru. C. griseus Grev. 1863, v. galapagensis Grun. in v H., 1880 (Gr. & St., 1887.) Oamaru. C. inaequalis Gr. & St. (Gr. & St., 1887.) Oamaru. C. kuetzingii A. S., 1876. (Gr. & St., 1887.) Oamaru. C. micans A. S., 1886, 139. (Petit, 1877.) Lyall Bay. C. minor Ehr., 1833. (Gr. & St., 1887.) Oamaru. C. nitidus Greg., 1857. (Petit, 1877; Gr. & St., 1887.) Lyall Bay, Oamaru. C. oamaruensis Gr. & St., 1887. v. C. concinnus. C. oblongus Grev., 1866. (Gr. & St., 1887.) Oamaru. C. oculus-iridis Ehr., 1839. (Gr. & St., 1887.) Oamaru. C. partitus Gr. & St., 1887. (A. S., 1890, 163, 5.) Oamaru. C. radiolatus Ehr., 1854. (Petit, 1877.) Lyall Bay. C. radiosus Grun., 1884. (Gr. & St., 1887.) Oamaru. C. rothii Grun., 1884. (Gr. & St., 1887.) Oamaru. C. scintillans Grev., 1865. (Gr. & St., 1887.) Oamaru. C. spinifer Gr. & St., 1887. (A. S., 1890, 164, 2.) Oamaru. C. splendidus Grev. (A. S., 1875, 65, 11.) Australia. C. sublineatus Grun., 1884. (A. S., 1890, 138, 7.) Oamaru. C. subtilis Ehr., 1841. (Petit, 1877; Gr. & St., 1887.) Lyall Bay, Oamaru. C. superbus Hardm. MS. (A. S., 1890, 163, 8.) Oamaru. C. symbolophorus Grun., 1884. (A. S., 1890, 138, 7.) Oamaru. C. vetustissimus Pant., 1863. (A. S., 1890, 163, 6.) Oamaru. Genus Pyxidicula Ehr., 1833 Frustules globular, solitary or in short chains; valves more or less hemispherical, areolate, devoid of spines; differs from Coscinodiscus in the shape of the valves, which resembles that of Hyalodiscus, from Stephanopyxis in the absence of spines, and from Melosira and Hyalodiscus in the lack of differentiation of any central area on the valves. 31. Pyxidicula cruciata Ehr. (Plate 32, Fig. 16a, b, c). Ehr, 1833, 3, 8. Boyer, 1916, 19, 38, 8. Coscinodiscus cruciatus Kütz., 1844, 132, 28, 10. Cells solitary or in pairs; valves hemispherical with large, hexagonal areolae, largest at centre, but more or less uniform towards valve margins; no constriction between valve and girdle, no spines, spinules or processes. Diameter, 20–30μ.

Distribution. Australia: Very rare in Bass Strait, in bottom mud between 60 and 120 m depth off Port Hacking; Heron Island. New Zealand: Auckland Harbour; Oamaru (Gr. & St., 1887). Also recorded from Oamaru by Ralfs (in Pritch., 1861) are Xanthiopyxis (Pyxidicula?] oblonga and X. (Pyxidicula) constricta (Ehr.); Ralfs, however, queries the true affinity of the genus Xanthiopyxis. Genus Charcotia M. Perag., 1921 Cells solitary, small, discoid, with dissimilar valves, marked with fine radial striations arising from an irregular ring of puncta at outer edge of central area. 32. Charcotia bifrons (Castr.) Perag. (Plate 32, Fig. 17). Perag. M., 1921, 78. Hendey, 1937, 256. Coscinodiscus bifrons Castr., 1886, 156. Valves flat or nearly so, finely radially striate; margin finely striate. Diameter, 50μ. Distribution. West of Bass Strait,-together with warm water species. Recorded from the Southern Ocean by Hendey, Peragallo and Castracane. Genus Planktoniella (Wallich) Schütt Cells solitary, discoid, surrounded by a hyaline wing of extra-cellular chambers strengthened by radial rays; valves flat, areolate; chromatophore numerous, small. 33. Planktoniella sol (Wallich) Schütt (Plate 32, Fig. 18). Schütt, 1893, 20, 8. Boden, 1950, 348. Coscinodiscus sol Wallich, 1860, 38, 2, 12. Cestodiscus sol Grun. in Cl. and Grun., 1880, 129, 6. Description as for genus. Overall diameter, 100–250μ. Distribution. Oceanic, tropical-sub-tropical waters. Australia: Sandy Cape to Storm Bay, May to September; off King Island. New Zealand: South of Campbell Island to lat. 57° S. in December. Family Actinodiscaceae Genus Actinoptychus Ehr., 1839 Cells solitary; frustules cylindrical–discoid, in girdle view, undulate; valve divided into six or more sectors, alternately raised and depressed; surface areolate, and punctate, varying in alternate divisions; the areolation is confined to the outer layer of the valve, while the punctation is usually on an inner valve, which is often found detached; marginal processes three or more; umbilicus circular or angular, hyaline. Key to the Species of Actinoptychus 1. Surface of both layers of valve punctate A. adriaticus Surface of one layer areolate 2. 2. Sectors less than 10 A. senarius. Sectors 10 to 20 A. splendens. 34. Actinoptychus senarius (Ehr.) Ehr. (Plate 32, Fig. 19). Ehr., 1843, 6, 1, 1, 27. Hendey, 1951, 32. Actinocyclus senarius Ehr., 1838, 172, 21, 6. A. undulatus Kütz. 1844, 132, 1, 24. Cells solitary; frustule discoid, valve surface with six to eight sectors, alternately raised and depressed; surface coarsely areolate with larger areolae towards the margin, and inner layer punctate in radiating striae, which are not related to the areolae; each sector with a short spine near valve margin; flange also finely punctate, irregularly thickened. Diameter, 32 to 74μ. Distribution. At times estuarine-neritic but chiefly marine. Largely benthic but occurs in algal washings and in plankton, uncommon on fouling test plates. Australia: Booby I., Port Stephens, Port Hacking, Pedra Blanca; infrequent. New Zealand: Auckland Harbour, Lyall Bay (Petit, 1877).

35. Actinoptychus adriaticus Grun. (Plate 32, Fig. 20). Grun., 1863, 160, 13, 20. Cells solitary; frustules discoid; valve surface almost flat (slightly undulate), sectors 6–8, cuneate to cordate: central area large; surface punctate, both inner and outer series of puncta in linear rows. Diameter, 50μ. Distribution. Australia: Heron Island. 36. Actinoptvchus splendens (Shadbolt) Ralfs (Plate 32, Fig. 21). Ralfs in Pritch, 1861, 840. Gran and Angst, 1931, 453, 31. Actinosphenia splendens Shadbolt, 1854, 6. Actinoptychus glabratus v. incisus Grun in A. S, 1890, 154, 2. Cells solitary, discoid, radially undulate; central area circular or stellate, sectors 10–20, cuneate; surface of outer layer of valve finely punctate, inner layer coarsely areolate. Diameter, 60μ. Distribution. Australia: Heron Island. New Zealand: Oamaru, Lyall Bay (Gr. & St., 1887; Petit, 1877). The following additional species have been recorded by previous authors:– A. decorans Grun., 1884. (A. S., 1890, 173, 3) Oamaru. A. maculatus Gr & St., 1887 (Bover, 1927.) Oamaru. A. molleri Grun., 1884. (A. S., 1890, 154, 5.) Oamaru. A. nitidus Grun, 1884. (Gr. & St., 1887, 64.) Oamaru. A. pericavatus Grun, 1891. (A. S., 1890, 173, 3.) Oamaru. A. pulchellus Grun., 1884 v. tenera Gr. & St. (Gr. & St., 1887). Oamaru. A. punctatus Ehr., 1843. (Petit, 1877.) Lyall Bay. A. racemosus A. S., 1890. (A. S., 1890, 153, 2.) Oamaru. A. undulatus (A. senarius). A. vulgaris Schum v. maculata Gr. & St., 1887 v. A. maculatus. A. wittii Janisch (A. S., 1886, 100, 12). Oamaru. Genus Aulacodiscus Ehr., 1844 Cells solitary, usually circular; frustule in valve view with central area level, becoming inflated at the processes; with or without rounded or irregularly shaped central markings; sculpture rounded, bead-like or angular in more or less straight radiating rows, more pronounced along the furrows which run from the centre to the processes; processes pronounced varying greatly in number, cylindrical and constricted at the base. Key to the Species of Aulacodiscus Frustules with pearl-like markings A. beeveriae. Frustules with polygonal markings A. margaritaceus. 37. Aulacodiscus beeveriae (Johnson) Ralfs (Plate 32, Fig. 22). Ralfs in Pritch, 1861, 844, 6, 5. Cells solitary, circular; frustule in valve view, flat, surface irregularly marked with pearl-like sculpture in rather distant, radiating lines, rows of areolae from central area to processes forming two parallel lines; valve margin striate; processes submarginal, three to four in number, slightly inflated at the base. Diameter, 280μ. Distribution. Rare. Australia: One locality, Clarence River (New South Wales); also type locality. (In G. West's collection; also from the northern rivers of New South Wales.) New Zealand: Oamaru (Grove & Sturt, 1886). 38. Aulacodiscus margaritaceus Ralfs (Plate 32, Fig. 23 a, b) Ralfs in Pritch, 1861, 844. Cells solitary, circular; frustule with central space of valve small and irregular; sculpture of valve small, polygonal, radiating markings; valve processes 3–10, inflated at the base. Diameter, 338–380μ. Distribution. Uncommon. Australia: Port Hacking; bottom mud sample; off Port Albert; previously recorded from Australia by Rattray, 1888 (also in West's collection). New Zealand: Oamaru (Gr. & St., 1887). The following additional species of Aulacodiscus have been recorded by previous authors:–

A. amoenus Grev., 1864. (As v. sparsoradiata Gr. & St., 1887.) Oamaru. (See Rattray, 1888.) A. angulatus Grev., 1863. (Gr. & St., 1886, 9; 1887, 76; A. S., 190, 161, 4.) Oamaru. A. aucklandicus Grun. in A. S., 1875. (A. S., 1875, 41, 3.) Auckland Island, Whangarei. A. barbadensis Ralfs in Pritch., 1861. (Gr. & St., 1887, 146.) Oamaru. A. carruthersianus Kitt. & Gr. (A. S., 1876.) King George Sound. A. cellulosus Gr. & St., 1886. (A. S, 1890, 161, 5; Gr. & St., 1886; v. plana Gr. & St., 1887, 140.) Oamaru. A. comberi Arn. Ralfs in Pritch., 1861. (Gr. & St., 1886, 8.) Oamaru. v. oamaruensis (Gr. & St., 1887.) Oamaru. A. convexus Gr. & St. (Gr. & St., 1887, 140.) Oamaru. A. coronatus Gr. MS. (Ratt., 1888, 379.) Oamaru. A. crux Ehr., 1844. (A. S., 1890, 162, 4.) Oamaru. v. subsquamosa Grun. & Gr. (in A. S., 1890, 157, 1.) Oamaru. A. decorus Grev., 1864, in Gr. & St., 1886 is A. elegans Gr. & St., 1887. A. dispersus Ratt., 1888 = A. spectabilis Gr. & St., 1887. 141, non Grev., 1864. Oamaru. A. elegans Gr. & St. (Gr. & St., 1887, 140.) Oamaru. A. huttonii Gr. & St. (Gr. & St., 1887, 140.) Oamaru. A. intumescens Ratt., 1888. (Ratt., 1888, 359.) Oamaru. A. invictus A. S. (A. S., 1890, 170, 1.) Australia. A. janischii Gr. & St. = A. stoschii Jan. Gr. & St., 1886, 8. (Gr. & St, 1887, 146.) Oamaru. v. abrupta Gr. & St., (Gr. & St., 1887, 139.) Oamaru. A. kittonii (Arn M.S.) Ralfs in Pritch., 1861, 844. Type 16c. N.Z. (Boyer. 1927, 79; Ratt., 1888.) Bay of Islands. A. notatus Gr. & St., 1886. (See A. barbadensis Ralfs.) A. novae-zeelandica Gr. (in A. S., 1893, 201, 9). Oamaru. A. patulus Grun. (in A. S., 1888). Oamaru. A. petersii Ehr., 1845. (Ralfs in Pritch., 1861; Gr. & St., 1886, 9.) Oamaru. A. radiosa Grev., 1863. (Gr. & St., 1887; A. S., 1890, 157, 1.) Oamaru. A. rattrayi Gr. & St., 1887, 139 = A. beeveriae of Gr. & St., 1886. A. sollittianus Norman, 1863, v. novae zeelandica Gr. & St., 1886 (Gr. & St., 9; A. S., 1890, 169, 10.) Oamaru. A. spectabilis Grev., 1863. (Gr. & St., 1887, 141.) v. A. dispersus Ratt., 1888. A. umbonatus Grev., 1864 var dirupta Gr. & St. (Gr. & St., 1887). Oamaru. Sub-order Auliscineae Family Auliscaceae Genus Auliscus Ehr., 1843 Cells solitary; frustules cylindrical; valves circular or subcircular, with two or three short, wide cylindrical processes and hyaline surfaces near ends of longitudinal axis in a line oblique to it; valve surfaces plane, except near processes; central area hyaline, usually circular; markings of two kinds, granules radiating or scattered and radiating and prominent or indistinct costae; girdle zone with rows of fine puncta. 39. Auliscus sculptus (W. Sm.) Ralfs (Plate 32, Fig. 24). Ralfs in Pritch., 1861, 845. Boyer, 1927, 94. Eupodiscus sculptus W. Sm, 1853, 25, 4, 42. A. caelatus Bail., 1853, 6, 3–4. Cells solitary; frustules in valve view elliptical or sub-circular, with 2 raised processes or ocelli on each valve; surface of valves with 6 sets of curved costae, four radiating from the ocelli and two from the margin towards the central area Length, 38–60μ Boyer (1927) finds difficulty in separating A. sculplus from A. caelatus, and our material from the same locality shows intergrades We therefore consider the two species synonymous.

Distributoin. Estuarine-neritic from algae and Zostera and occasionally from fouling test plates; occasionally in coastal plankton. Australia: Moreton Bay, Lake Macquarie, Port Hacking, Port Lincoln (A. S., 1875, 32, 23). New Zealand: Foveaux Strait (Petit, 1877), Oamaru (Ratt., 1888, Gr. &St., 1886). The following species of Auliscus have been previously recorded:— A. accedens Ratt. (Ratt., 1888, 871). Oamaru. A. australiensis Grev., 1863. (Ratt., 1888, 868.) Australia. A. barbadensis Grev., 1865 = A. linearis Gr. & St. (Gr. & St., 1886, 10). Oamaru. A. coincidens A. S. (A. S., 1890, 171, 1.) Oamaru. A. convolutus Ratt. (Ratt., 1888.) Oamaru. A. fenestratus Gr. & St. (like A. pruinosus Bail.), (Gr. & St., 1887). Oamaru. A. fractus Gr. & Kitt. in litt. (Ratt., 1888, 889.) King George Sound. A. grevillei Jan. (Gr. & St., 1887, 78.) Oamaru. A. grunovii A. S., 1875 v. subpuncta Ratt. (Ratt., 1888). Oamaru. A. hardmanianus Grev., 1866. (Gr. & St., 1887, 78.) Oamaru. A. inflatus Gr. & St. (Gr. & St., 1887, 141.) Oamaru. A. intercedens Jan. in A. S., 1875. (Ratt., 1888.) Gulf of Carpentaria. A. intermedius Gr. & St. in litt. (Ratt., 1888, 890.) Oamaru. A. interruptus Ratt. (Ratt., 1888, 880.) Oamaru. A. inflatus Gr. & St. (Gr. & St., 1887, 141.) Oamaru. A. lineatus Gr. & St. (Gr. & St. 1887, 141.) Oamaru. A. lucidus Ratt. (Ratt., 1888, 891.) Gulf of Carpentaria. A. lunatus Gr. & St. in litt. (Ratt., 1888.) Oamaru. A. macraeanus Grev., 1863. (Ratt., 1888.) Oamaru. A. moronensis Grev. 1864. (Ratt., 1888, 882.) Oamaru. A. (Pseudauliscus) notatus Grev., 1865 (Gr. & St., 1886, 10). Oamaru. A. oamaruensis Gr. & St. (Gr. & St, 1886, 10.) Oamaru. A. ovalis Arn. Ralfs in Pritch., 1861. (Ratt., 1888, 891.) Oamaru. A. pectinatus Ratt. (Ratt., 1888, 878). Oamaru. A. propinquus Gr. & St., (Gr. & St., 1887, 141). Oamaru. A. pruinosus Bail., 1853. (A. S., 1875, 31; Petit, 1877; Ratt., 1888.) Gulf of Carpentaria; Lyall Bay, Oamaru. A. punctatus Bail., 1853. (A. S., 1875, 31; Gr. & St., 1887, 77.) Gulf of Carpentaria. Oamaru. A. racemosus Ralfs, 1861. (Gr. & St., 1886, 10.) Oamaru. A. raeanus Ratt., (Ratt., 1888, 879). Oamaru. A. rhipis A. S., 1875, 32. (Ratt., 1888, 884.) King George Sound. A. sigillum Brun, (A. S., 1890, 171, 7). Oamaru. A. stelliger Petit. (Petit, 1877, 36.) Type loc. Campbell Island. A. stoeckhardti Jan., 1861. v.inconspicua Ratt., 1888. Oamaru. v.subpunctata Ratt., 1888. Oamaru. v.aspera Gr. (A. S., 1900, 19). Oamaru. A. subcalatus Ratt. (Ratt., 1888, 889). Oamaru. A. transpennatus Brun, 1891. (A. S., 1890, 171, 10.) Genus Asterolampra Ehr., 1845 Cells solitary, discoid; valves with large, hyaline central region at least ⅓ diameter of valve; rays of equal width, tapering towards margin, outer ends with minute spine; hyaline centre divided into cunieform segments; fine areolation between rays; central area reticulate or divided by straight lines into the same number of parts as rays. 40. Asterolampra marylandica Ehr. (Plate 32, Fig. 26). Ehr., 1844, 76, 10. Allen and Cupp, 1935, 122, 21.

Cells discoid; valves with large, hyaline centre, divided into seven sectors; 7 narrow, hyaline rays reaching margin, with short marginal processes; segments between rays regularly areolate. Diameter, 80μ. Distribution. Australia: Port Hacking, very rare. New Zealand: Oamaru (Gr & St., 1887, 66). The following additional species have been recorded by previous authors:— A. affinis Bail. v. punctifera Gr. (A. S., 1893, 202, 18). Oamaru. A. decora Grev., 1862. (Gr. & St., 1887, 66.) Oamaru. A. insignis A. S., 1886. (A. S., 1888, 137, 1–3.) Oamaru. A. uraster Gr. & St. (Gr. & St., 1887, 143). Oamaru. A. vulgaris Grev., 1862b. (Gr. & St., 1887, 66; A. S., 1893, 202, 114–116.) Oamaru. Genus Asteromphalus Ehr. 1844 Cells discoid or slightly oval, solitary; valves radially undulate, with a central smooth area, and smooth rays from centre to margin, one ray narrower than others; outer part of valve between rays areolate; girdle undulate, following rays. 41. Asteromphalus hookeri Ehr (Plate 32, Fig. 27) Ehr., 1844, 200, 37. Boden, 1950, 354, 30. A. buchii Ehr., 1844, 200, 4. A. cuvieri Ehr., 1844, 200, 7. A. humboldtii Ehr., 1844, 200, 6. Asterolampra hookeri Grev., 1860, 114, 53. A. robustus Castr., 1886; Manguin, 1954, 15, 2, 7. Cells discoid, solitary; valves somewhat convex, undulate, divided by 7 to 9 hyaline rays, one narrower than the rest; hyaline area about ½ diameter; sectors finely areolate; central area with branched lines from near centre of valve to areolate areas. Diameter, 30μ. Distribution. Type locality, Antarctic. Found in B.A.N.Z.A.R.E. material south of Tasmania and in collections from the Antarctic Ocean south of New Zealand; recorded from Heard Island by Manguin as A. robustus Castr. A. flabellatus Breb., 1857, is also recorded from Lyall Bay by Petit, 1877. Family Biddulphiaceae Genus Cerataulina Perag., 1892 ex Schütt, 1896 Cells cylindrical, in chains; valves slightly rounded at margins, with two stumpy processes near margins, attaching to corresponding processes of next cell by a small, curved hair fitting into a sheath in next cell; cell wall weakly siliceous; intercalary bands numerous. 42. Cerataulina pelagica (Cl.) Hendey (Plate 36, Fig. 18). Hendey, 1937, 279. Zygoceras? pelagicum Cl. 1889, 54. Cerataulina bergonii (H. Perag.) Schütt, 1896, 95; Lebour, 1930, 185; Gran and Angst, 1931, 489, 73; Allen and Cupp, 1935, 149, 86. Cerataulus (Cerataulina) bergonii Perag, 1892, 103, 15, 16. Cells cylindrical, with rounded corners, united to form chains which are often twisted, and may be straight or curved; valves slightly convex, with 2 short processes which terminate in a short spine uniting cells; intercalary bands hard to see. Diameter, 20–30μ. Distribution. Australia: East coast, Moreton Bay to Eden; Swan River. 43. Cerataulina chapmanii n.sp. (Plate 32, Fig. 28). (Type specimen at Marine Biological Laboratory, Cronulla.) Frustulia in axe majore leve rotata; valvae ellipticae cum striis fortibus ad axis mediam parallelibus; centro hyalino; cum duobus ocellis et spinulis marginem prope; 40 × 22μ. Frustules more strongly siliceous than those of C. pelagica slightly twisted on pervalvar axis, in valve view elliptical, with coarse striae parallel to longitudinal axis, hyaline centre, and two ocelli near margins; two spines arising at edge of ocelli; in girdle view, frustule is rectangular, ocelli appearing as very short processes; distinct thickening just below processes; girdle zone with several intercalary bands, faintly punctate. Distribution. Port Fairy region; planktonic, associated with warm water and some Antarctic species.

Genus Biddulphia Gray, 1821 Cells solitary or joined by processes to form straight or zig-zag chains; frustules moderately to heavily silicified; valves oval to crenate, with 2 rounded or blunt processes, and at times, with prominent spines; girdle band sharply differentiated from valves usually with monili-form striae or coarse, scattered puncta. Key to the Genus Biddulphia 1 Valves heavily silicified, areolate or punctate 2 Valves lightly silicified, sculpture not obvious 6. 2 Valves radially punctate 3. Valves not radially punctate 4. 3. Central area of valve radially punctate, margin areolate B. sansibarica Valve radially punctate, frustule obviously distorted B. turgida Valve punctate radially from processes and central area, frustule not obviously distorted B. thumu 4. 2 angles of valve with short horn-like process, 2 with short, blunt processes B. dubia Processes of equal size 5 5 Processes sub-conical at angle to pervalvar axis 5 Processes hemispherical, parallel to pervalvar axis B. pulchella 6 Valve surface heavily punctate B. aurita Valve surface heavily reticulate B. reticulata 7. Processes long and slender B. mobiliensis Processes short and blunt B. regia. Processes short and slender B. sinensis. 44. Biddulphia mobiliensis (Bail) Grun (Plate 36, Fig. 19). Grun, 1880–1885 in van H., 103 a. Boyer, 1901, 698; 1927, 122. Zygoceros (Denticella) mobiliensis Bail, 1851, 40. Cells solitary or united in chains by spines; valves elliptic-lanceolate, surface convex with flat central portion separated from rest of valve by a slightly elevated ridge, which extends in two more or less sigmoid lines from one process to the other; on opposite sides of central portion is a small, conical projection from which extend one or two long, slender spines; processes slender, capitate, surface of valve delicately punctate. Width, 50–200μ Distribution Tropical oceanic. Australia: Thursday Island, Moreton Bay, Port Jackson, Port Hacking, June to December; Broome; Coral Sea indicator, on east coast. New Zealand: Hauraki Gulf to Port Lyttelton. 45. Biddulphia dubia (Brightw) Cl (Plate 36, Fig. 20) ex Allen and Cupp, 1935. 148, 84. Cells solitary; valves rhombic-lanceolate; in girdle view with 2 angles having a stout horn-like process, two a shorter, blunter process; sculpture large, with irregular, hexagonal areolae, minutely punctate; girdle areolate Width, 50–60μ This is probably a form of B. reticulata It is not Triceratium dubium Brightw. Distribution. Off Maryborough; rare. 46. Biddulphia sansibarica A. S.(Plate 32, Fig. 29) A. S, 1888, 122, 10–12. Cells solitary; valve view oval with two broad marginal processes, several spines and spinules surrounding central area, which is radially punctate; marginal region heavily areolate; girdle zone very marked, with hexagonal areolae, processes areolate Width 15–30μ. Distribution. Heron Island. 47. Biddulphia thumii (A S) Boyer (Plate 32, Fig. 25) Boyer, 1901, 712. Cerataulus thumi A. S, 1886, 115, 1. C. hungaricus Pant, 1886, 26, 375. Valve suborbicular, with 2 short, broad, truncate processes Surface finely punctate, puncta radiating from processes circularly towards margin and from a spindle-shaped, slightly raised central area to margin Diameter, 80μ. Distribution. Bass Strait previously recorded from fossil beds. 48. Biddulphia regia (Schultze) Ost. (Plate 36, Fig. 21). Ost., 1908, 7, 3. Boden, 1950, 395, 78. Denticella regia Schultze, 1858, 21, 105.

Cells somewhat rectangular in girdle view, elliptic-lanceolate in valve view; processes narrow, often distinctly capitate, broader and shorter than in B. mobiliensis; central area only slightly raised, with 2 long spines curving inwards towards ends; valve surface areolate. Width, 50–200μ. Distribution. Thursday Island, Shark Bay. 49. Biddulphia chinensis Grev. (Plate 33, Fig. 30). Grev., 1866, 81, 9, 16. Allen and Cupp, 1935, 146, 81. Cells solitary or in short chains, linked by spines; rectangular in girdle view, elliptic-lanceolate in valve view; processes thin, relatively short, almost parallel with valve margin; spines long, emanating from small protuberances close to processes, curved near tips; central area depressed or flat; cell wall weakly siliceous, delicately areolate. Width 50–200μ. Distribution. Australia: Sandy Cape to Babel Island, January to September. New Zealand: Auckland Harbour, Wellington, Port Lyttelton, also with other warm water forms at 57° 47′ S.; 169° 06′ E. in December; Oamaru (Gr. and St., 1887). 50. Biddulphia turgida (Ehr.) W. Sm. (Plate 33, Fig. 31) W. Sm., 1856, 50, 62, 384. Boyer, 1927, 129. Cerataulus turgidus Ehr., 1843, 71. Cells solitary; valves elliptical, convex; processes very large, cylindrical, truncate, obliquely opposite, near the ends, and, owing to the distortion of the frustule, directed sideways; two stout spines between processes, frequently forked; surface with undulating lines of puncta; in girdle view, subglobose and twisted on longitudinal axis Width, 80μ. Distribution. Lake Macquarie, Port Hacking; Bass Strait (western end); rare. 51. Biddulphia pulchella Gray (Plate 33, Fig. 32). Gray, 1821, 1, 294. Hendey, 1951, 34. Conferva biddulphiana Smith, J. E., 1807, 1762 (upper figs.). Biddulphia biddulphiana (Smith). Cells solitary or in chains; frustules cylindrical in girdle view, elliptical in valve view; valves elliptical with undulating sides divided by costae into 3 or more sections; ends with large, globular or sub-conical processes, finely porulate; valve surface between costae coarsely areolate, reticulate; areolae rounded, arranged concentrically or irregularly in centre, concentrically with processes towards margin; in girdle view longitudinal or transverse; valve mantle deep; girdle punctate, striate; plastids numerous. Length, 45–120μ Distribution. Oceanic-estuarine, benthic-epontic. Australia: Botany Bay, Port Phillip, Port Hacking; planktonic, Port Hacking; rare in marine fouling associations. New Zealand: Auckland Harbour; Foveaux Strait (Petit, 1877). 52. Biddulphia aurita (Lyngbye) de Brébisson (Plate 33, Fig. 33). de Brébisson, 1838, 12. W. Sm., 1856, 49, 45, 319. Boyer, 1927, 122. Hendey, 1951, 35, 12, 7. Diatoma auritum Lyngbye, 1830, 32. Odontella aurita Ag., 1830–32, 56. Cells united in straight or zig-zag chains; frustules in valve view lanceolate; processes inflated at base, tapering at ends; valves with small, radial puncta and small lateral spines on convex central area; girdle band sharply differentited from valve; plastids numerous, reniform to elliptical. Length, 40–60μ. Distribution. Estuarine-neritic, marine to brackish water, epontic on plants, rock, and fouling test plates, benthic in estuaries; planktonic. Australia: Moreton Bay, Lake Macquarie, Port Jackson, Botany Bay, Port Hacking, Eden, Port Phillip. New Zealand: Auckland Harbour. 53. Biddulphia reticulata Roper (Plate 33, Fig. 34, a, b). Roper, 1859, 7, 14. Boyer, 1927, 128. Cells united in straight or zig-zag chains; frustules in valve view oval, with processes as in B. aurita; valve surface with large, hexagonal areolae; girdle with a series of well-defined puncta. Diameter, 54μ.

Distribution. Australia epontic at Port Hacking, planktonic at Port Stephens 50 mile station, western Bass Strait. New Zealand: Auckland Harbour; fossil from Oamaru (Gr. & St., 1887). The following Biddulphia species have been recorded by previous authors:— B. (Anaulus) birostratus Grun. in v H., 1885. (Petit, 1877.) Lyall Bay. B. dissipata Gr. & St. (Gr. & St., 1887, 134.) Oamaru. B. elaborata (as Kittonia elaborata.) (Gr. & St. 1886, 1887.) Oamaru. B. elegantula Grev, 1865 (is B. tridens Ehr., 1840) (Gr. & St., 1886, 325.) Oamaru. B. johnsoniana Grev., 1866. (Cerataulus johnsoniana) (Gr & St, 1886, 326). Oamaru. B. lata Gr. & St (Gr & St, 1887, 135; A. S., 1890, 172, 7). Oamaru. B. macdonaldii Norman, Ralfs in Pritch., 1861. (Pritch., 1861, 849. Shark Bay. B. (Cerataulus) marginata Gr & St., 1887 (Gr. and St, 1887) = Bidd. marginata n. comb. Oamaru. B. miraudosa Brun, 1891 (A. S, 1890, 172, 10). Oamaru. B. oamaruensis Gr. & St. (Gr. & St. 1886, 325). Oamaru. B. pedalis Gr & St (Gr & St, 1887, 74). Oamaru. B. podagrosa Grev, 1866 var. (Gr & St. 1887, 74). Oamaru. B. (Cerataulus) polymorpha f. minor v H., 1885. (Gr. & St., 1887, 75.) B. punctata Grev., 1864. (Gr & St., 1886, 325.) Oamaru. B. reversa Gr. & St (Gr & St., 1887, 134). Oamaru. B. rigida A S., 1886 (A S., 1886, 120, 1, 2.) Oamaru. B (Cerataulus) subangulata Gr & St. (Gr. & St., 1886, 325). Oamaru. B. tenera Gr. & St. (Gr, & St., 1887, 134). Oamaru. B. tridens Ehr., 1840. (B. tuomeyi (Bail.) Roper, 1859.) B. tuomeyi (Bail.) Roper, 1859. (See B. tridens (Ehr., 1840) Boyer, 1900–close to B pulchella (Gr. & St., 1886, 324.) Oamaru. B. (Kittonia) virgata Gr & St. (Gr & St. 1887). Oamaru. B. vittata Gr & St (Gr & St. 1887. 134) Oamaru. Genus Triceratium Ehr., 1839 Cells solitary; frustules in valve view, three- to many-sided, each angle furnished with horn-like processes, usually heavily sculptured with hexagonal areolae or coarse puncta arranged linearly; girdle sculpture often fine moniliform striae. Key to the Species of Triceratium 1. In valve view usually six-sided with first and third corners produced T. dubium Not usually six-sided, if so sides even 2. 2 Valves costate as well as areolate 3. Valves not costate 4. 3 Ribs radiating from margin T. alternans. Ribs of irregular pattern T. pentacrium 4 Areolae stellate T. pardus. Areolae hexagonal 5 Areolae irregular 6 5 Valve with spines T. robertsianum Valve without spines T. favus. 6. Areolae smaller in the centre, fairly regular T. tessellatum. Irregular reticulation T. reticulatum. 54. Triceratium favus Ehr (Plate 33, Fig. 35) Ehr., 1839, 4, 10. Schönfeldt, 1907, 89, 3, 334. Hendey, 1937, 283. Biddulphia favus van H, 1885, 208, 107, 1–5. T. fimbriatum Wallich, 1860, Boyer, 1900, 706, 1927, 133. Cells solitary; frustules in valve view, triangular, in girdle view rectangular; valve margin.

more or less straight, angles with processes; surface with large hexagonal areolae, usually arranged in straight lines. Length, 98–106μ. Distribution. Estuarine-neritic and planktonic; marine. Australia: benthic from Heron Island; Port Hacking; planktonic from New South Wales, Bass Strait, and southern Tasmania (32–43° S.). New Zealand: Wellington Harbour, Foveaux Strait (Petit, 1877); Oamaru (Gr. & St., 1886). 55. Triceratium robertsianum Grev. (Plate 33, Fig. 36, a, b). Grev., 1863, 231, 9, 9. Subrahmanyan, 1946, 150, 272. Triceratium brookei Leuduger-Fortmorel, in A. S, 1875, 8, 82, 10. Biddulphia robertsiana Boyer, 1900, 707; 1927, 134. Cells solitary or in chains; frustules in valve view triangular or quadrangular with convex margins; valves with more or less hexagonal areolae, slightly smaller towards the centre: angles slightly produced with prominent, obtuse processes; girdle with fine moniliform striae Breadth 90–103μ. Distribution. Estuarine-neritic, benthic and planktonic. Australia: Clarence River, Port Hacking, Bass Strait; a common bottom form. (Type locality, Queensland, Grev., 1863.) 56. Triceratium alternans Bail. (Plate 33, Fig. 37) Bailey, 1851, 2, 40, 55. W Sm., 1853, 26, 5, 45; 30, 45. Hendey, 1951, 34, 7, 10. Biddulphia alternans, van H, 1885, 208; Boyer, 1927, 137. Cells solitary; frustules in valve view triangular, in girdle view rectangular; processes almost colinear with valve, giving a slightly irregular margin and overall triangular shape in valve view; valves with up to four costae extending from margin towards centre; surface areolate, areolae in rows almost perpendicular to apices, diminishing in size towards margins; girdle areolate. Length, 48μ. Distribution. Estuarine-neritic; marine; benthic, epontic from algal and Zostera washings. Australia: Moreton Bav, Port Hacking Moderately common New Zealand: Wellington Harbour, Lyall Bay (Petit, 1877). 57. Triceratium pentacrinum (Ehr.) Wallich. (Plate 33, Fig. 38). Wallich, 1858, 6, 249. Amphipentas pentacrinus Ehr., 1840, 10. Biddulphia pentacrinus, Bover, 1901, 53, 717; 1927, 135. Cells solitary; frustules in valve view quadrangular or pentagonal with concave sides; ancles produced with short, rounded processes surface nearly flat, with hexagonal reticulations radiating from centre and ribs formed by variation in the thickness of the walls, making an irregullar pattern; girdle with pentagonal markings. Diameter. 60μ Distribution. Australia: From coral reef at Heron Island, Queensland, and Bass Strait (western part associated with warm water flora). New Zealand: Oamaru (Gr. & St., 1886), as T. spinosum var ornata, Gr. & St. 58. Triceratium pardus A. S. (Plate 33, Fig. 39) A. S., 1875, 79, 15. Cells solitary; frustules in valve view triangular (pentagonal?) with slightly convex margins; processes slightly protuberant, rounded; surface reticulate, with heavy and irregular thickenings forming deep and characteristic stellate areolae, processes finely punctate Length, 50μ. Distribution. Marine mud from Heron Island, Port Hacking. Recorded by Schmidt from Celebes. 59. Triceratium dubium Brightw. (Plate 33, Fig. 40). Brightw., 1859, 180, 9, 12. Ralfs in Pritch., 1861, 857. A. S., 1875, 78, 28–30, 31. Cells minute, solitary, clypeate in valve view, with 6 angles, 1 and 5 produced; finely reticulate. Width, 20μ. Distribution. Heron Island, Port Hacking.

60. Triceratium tessellatum Grev. (Plate 33, Fig. 41). Grev., 1861, 71, 8, 14. Valves triangular, with straight or slightly concave sides and rounded angles; valve surface somewhat convex in centre, areolae hexagonal to subquadrate, smaller at centre arranged in somewhat concentric rows; angles with five puncta, almost hyaline. Width, 50μ. Distribution. Heron Island. 61. Triceratium reticulum Ehr. (Plate 33, Fig. 42). Ehr., 1844, 88, 18, 50, 33, 16, 13. T. sculptum Shadbolt, 1854, 2, 15. T. punctatum Brightw., 1856, 4, 275. de Sousa e Silva, 1953, 37, 11, 1. Biddulphia reticulum Boyer, 1926. T. obtusum Kutz. (by Petit, 1877) Valves triangular to polygonal, with straight or concave sides; angles rounded, sometimes produced; surface slightly elevated at centre and at angles, puncta angular, unequal, larger at centre; three or four spines may occur about half way between centre and margins, groups of puncta frequently occur arranged in 3 or 4 small circles. Width, 40–60μ. Distribution. Australia: Port Stephens (wide offshore), Port Hacking, Heron Island, Bass Strait. New Zealand: Lyall Bay (Petit, 1877), Oamaru (Gr. & St., 1886). A large number of Triceratium species have been recorded from this region, including the following:— T. americanum Ralfs in Pritch., 1861. (Gr. & St., 1886, 238; A. S., 1890, 159, 4.) Oamaru. T. arcticum Brightw., 1858. (Gr. & St., 1886, 326.) Oamaru. T. armatum Roper, 1859. (Petit, 1877, 36.) Foveaux Strait. T. auliscoides Gr. & St. (Gr. & St., 1887, 76.) Oamaru. T. brachiolatum Brightw., 1858b. (Petit, 1877, 36.) Foveaux Strait. T. cancellatum Grev. 1865. (Gr. & St., 1886, 329.) Oamaru. T. capitatum Ralfs in Pritch., 1861. (Gr. & St., 1886, 326.) Oamaru. T. castellatum West, 1860 (= T. umbilicatum Ralfs in Pritch., 1861). (Gr. & St., 1886, 327; A. S, 1890, 160, 27.) Oamaru. T. coelatum Jan. in A. S., 1875, 81, 19. (Gr. & St., 1886, 328.) Oamaru. T. concinnum Grev., 1864. (Gr. & St., 1887, 138.) Oamaru. T. compactum Brightw. MS. (Ralfs in Pritch, 1861, 853.) Australia. T. condecorum (Ehr.) A. S., 1875, 28. (Gr. & St., 1887, 138.) Oamaru. T. cordiferum Gr. & St. (Gr. & St., 1887, 136.) Oamaru. T. coscinoides Gr. & St., 1886, 327. (= T. favus.) T. crenulatum Gr. & St. (Gr. & St., 1886, 7). Oamaru. T. davyana Grev., 1862. (Gr. & St., 1886, 8.) Oamaru. T. denticulatum Grev., 1863. (Gr. & St., 1886, 328.) Oamaru. T. divisum Grun. in v H., 1885. (Gr. & St., 1886, 327.) Oamaru. T. dobreeanum Grev., 1865. (A. S., 1890, 168, 5.) Oamaru. Sydney in 15 fath. (type loc.). v. novae zeelandica Gr & St (Gr. & St., 1886, 328.) Oamaru. T. eccentricum Gr. & St. (Gr. & St., 1887, 137.) Oamaru. T. elaborata, (as Kittonia elaborata) Gr & St. (A. S., 1886, 116, 18.) Oamaru. T. exornatum Grev., 1865. (Gr. & St., 1887, 137.) Oamaru. T. fimbriatum Wallich, 1858. (= T. favus.) T. fractum (Walker & Chase) Ralfs in Pritch., 1861. (A. S., 1890, 166, 9, 10.) Oamaru. T. grande Brightw., 1858. (Gr. & St., 1887, 137.) Oamaru. T. harrisonianum Norm. & Grev. (is a Stictodiscus). (A. S., 1878, 75.) Oamaru. T. inelegans Grev., 1866. (Gr. & St., 1886, 328.) Oamaru. T. imarginatum Gr. & St. (Gr. & St., 1887, 76.) Oamaru. T. intermedium Gr. & St. (Gr. & St, 1886, 7.) Oamaru. T. kinkerianum Witt. (Gr. & St., 1886, 327.) Oamaru. T. lautourianum Gr. in A. S. (A. S., 1890, 160, 27.) Oamaru.

T. ligulatum (Trinacria) Grev., 1865. (Gr. & St., 1887, 63.) Oamaru. T. lineatum Grev., 1863. (Gr. & St., 1886, 7.) Oamaru. T. lobatum Grev., 1863. (Gr. & St., 1886, 328.) Oamaru. T. majus Gr. & St., 1887. (A. S., 1890, 168, 5.) Oamaru. T. montereyi Brightw., 1858b. (Gr. & St., 1887, 76.) Oamaru. T. morlandii Gr. & St. (Gr. & St., 1886, 7.) Oamaru. T. neglectum Grev., 1865. (Gr. & St., 1886, 7.) Oamaru. T. nitescens Grev., 1865. (Gr. & St., 1886.) Oamaru. T. oamaruense Gr. & St. 1886. (Gr. & St., 1886, 135.) Oamaru. v. sparsim punctata Gr. (Gr. & St., 1888; A. S., 1890, 159, 4.) Oamaru. T. obesum Grev., 1864. (Gr. & St., 1886, 6.) Oamaru. T. obtusum Kütz., 1849 (is T. reticulum Ehr.) (Petit, 1877). Lyall Bay. T. parallelum (Ehr.) Grev., 1865 f. trigona Gr. & St., 1886. (Gr. & St., 1886, 326.) Oamaru. T. partitum Grev., 1864. (Gr. & St., 1886, 327) = T. oamaruense Gr. & St., 1887, 135. Oamaru. T. papillatum Gr. & St. (Gr. & St., 1887, 76). Oamaru. T. parvulum (Amphitetras parvulum) Grev., 1863c. New Caledonia (type loc). T. pileolus v. jutlandica Grun., 1884. (Gr. & St., 1886, 64.) Oamaru. T. plenum Gr. & St., 1887. (Gr. & St., 1886; A. S., 1890, 159, 3.) Oamaru. T. plumosum Grev., 1864. (Gr. & St., 1887, 138.) Oamaru. T. pseudonervatum Gr. & St. (Gr. & St., 1887, 136.) Oamaru. T. pulvinar A. S., 1875. (A. S., 1890, 168, 7.) Oamaru. T. punctatum Brightw. (= T. reticulum Ehr.). T. quadricorne Grev., 1865. Woodlark I. (type loc.). T. rectangulare Gr. & St. (Gr. & St., 1887, 135.) Oamaru. T. repletum Grev., 1866. (Gr. & St., 1887, 138.) Oamaru. T. rugosum Gr. & St. (Gr. & St., 1887, 75, 135.) Oamaru. T. rotundatum Grev., 1861. (Gr. & St., 1886, 327.) Oamaru. T. sculptum Shadb., 1854 (= T. reticulum Ehr.). (Petit, 1877.) T. sexangulum Grev., 1865. Woodlark I. (type loc.). T. sexpartitum Gr. & St. (Gr. & St., 1887, 145.) Oamaru. T. shadboltianum Grev., 1866. (T. orbiculum Shad., 1854.) (Gr. & St., 1887, 138.) Oamaru. T. simulacrum (Trinacria) Gr. & St. (Gr. & St., 1887, 144.) Oamaru. T. spinosum Bail. v. ornata Gr, & St., 1886 (= T. pentacrinum). T. stokesianum Grev. 1866. (Gr. & St., 1887, 137.) Oamaru. T. trifotiatum Cl., 1881. (Cl., 1881.) New Zealand. T. trisulcatum Bail. MS. Ralfs in Pritch., 1861. (Gr. & St., 1887, 138.) Oamaru. T. unguiculatum Grev., 1864. (Gr. & St., 1886, 328.) Oamaru. T. venosum Brightw., 1858. (Gr. & St., 1886, 327.) Oamaru. T. venulosum Grev., 1864 (= T. tabellarium Brightw., 1856 (Gr. and St., 1886, 327.) Oamaru. T. ventricosa (Trinacria) Gr. & St. (Gr. & St., 1887, 63, 144), Oamaru. T. weissflogii Gr. & St. (Gr. & St., 1887, 136). Oamaru. T. weissii Grun. (Gr. & St., 1886, 238.) Oamaru. Genus Isthmia Agh., 1832 Cells solitary or in short zig-zag chains, stipitate, frustules rhomboidal or trapezoidal, asymmetric to pervalvar axis in girdle view, elliptic-lanceolate in valve view; valves dissimilar, elliptical to ovate, the end of one valve elevated into a protuberance or beak attached to the stipe, the other valve rising in a gradual elevation towards one end, girdle well developed, frequently persistent, and holding young frustules; plastids rounded granules. Key to the Species of Isthmia Costae present I. nervosa Costae absent I. enervis.

62. Isthmia nervosa Kütz. (Plate 34, Fig. 43). Kütz., 1844, 137, 19, 5. Boyer, 1927, 140. Cells solitary or in short chains; frustule trapezoidal in girdle view; valves with varying number of transapical costae extending to valve angle, and with hexagonal areolae; girdle areolate. Length, 120μ. Distribution. Estuarine-neritic, marine; chiefly benthic and epontic, but also planktonic. Australia: Moreton Bay, Port Hacking, Eden. Not common in Port Hacking; commoner in Moreton Bay. 63. Isthmia enervis Ehr., (Plate 34, Fig. 44). Ehr., 1838, 209. Kütz., 1844, 19, 4. Cells large, solitary or joined in short, zig-zag chains; frustules with apex of one valve produced to a blunt protuberance with fine pores; valve surface with large areolae, costae absent Length, 180μ. Distribution. Estuarine-neritic, marine; benthic, epontic. Australia: Fremantle Harbour, Waterhouse Island (Bass Strait), and Moreton Bay. Apparently more common in Western Australia than in eastern waters. New Zealand: Oamaru (Gr. & St., 1886). Genus Lithodesmium Ehr., 1840 Cells prismatic, united in straight chains by raised valve margin; frustules in girdle view with raised central portion, then constricted and sigmoid, in valve view prismatic, with slightly convex sides, slightly constricted towards apices; chloroplasts numerous, plate-like. 64. Lithodesmium undulatum Ehr. (Plate 36, Fig. 22). Ehr., 1840, 75, 4, 13. Lebour, 1930, 185, 145. Cells united in straight chains, triangular in valve view, with a rounded central portion continuous with rest of cell, in girdle view with swollen central portion and valve sigmoid towards margins. Width, 40–60μ. Distribution. Swan River; Lat. 34° S., 154° E.; Eastern Tasman near New Plymouth. Genus Hemiaulus Ehr., 1844 Cells solitary or in curved chains united by overlapping marginal processes; broadly elliptical in valve view, H-shaped in girdle view, cell wall strongly or weakly siliceous. Key to the Genera of Hemiaulus 1. Processes long 2. Processes comparatively short 3. 2. Apertures oval H. haucku. Apertures rectangular H. sinensis. 3 Cells rotund H. indicus. Cells flat or slightly rounded H. membranaceus. 65. Hemiaulus hauckii Grun. (Plate 36, Fig. 23). Grun. in Cl. and Grun., 1880, 103, 10. Boden, 1950, 397. Cells twisted, rectangular in girdle view, longer than broad, not noticeably swollen; with long, thin marginal processes forming an H; processes tapered at tip, tapers uniting with processes of adjoining cells, the whole forming curved chains; frustules weakly siliceous. Width, 20μ Distribution. Australia: Cape Moreton to Shoalhaven, May to September (Coral Sea indicator), St Vincent Gulf, Tasman Sea (30° 57′ S., 169° E., in June). New Zealand: Hauraki Gulf. 66. Hemiaulus sinensis Grev. (Plate 36, Fig. 24). Grev., 1865, 5, 9. Allen and Cupp, 1935, 150, 88. Cells in chains, united by long processes, ovate in valve view, H-shaped in girdle view, somewhat twisted; procesess adhering by a definite claw; frustule strongly siliceous, excentrically areolate. Width, 40μ. Distribution. Australia: Stradbroke Island to Babel Island, May to October; Broome.

67. Hemiaulus membranaceus Cl. (Plate 36, Fig. 24). Cl., 1873a, 6, 1, 5. Allen and Cupp, 1935, 151, 90. Cells in chains, varying in shape from almost square to 5–6 times wider (apical axis) than long (pervalvar axis); valves slightly convex, concave or nearly flat between processes, processes short, often pointed, uniting cells, frustules weakly siliceous, finely punctate. Width, 30μ Distribution. Australia: Sandy Cape to Babel Island, May to September; Broome. 68. Hemiaulus indicus Karsten (Plate 36, Fig. 25). Karsten, 1907, 394, 46, 4a. Allen and Cupp, 1935, 151, 89. Cells in chains, circular to elliptical in valve view, rotund to almost rectangular in girdle view, processes short, with finger-like extremities uniting cells. Width, 40μ Distribution. Cape Moreton. The following fossil species have been described from Oamaru by Grove and Sturt, 1886–7; and one by A. Schmidt, 1888. H. amplectans Gr. & St., 1887, 76. H. angustus Grev., 1865. H. barbadensis Grev., 1884. H. claviger A. S., 1888, 143, 56. H. dissimilis Gr. & St., 1887, 143. H. includens (Ehr.) Grun., 1884 (may be identical with H. capitatus Grev.). H. lyriformis Grev., 1865. H. ornithocephalus Grev., 1865. H. polymorphus Grun., 1884. H. tenuicornis Grev., 1865. Genus Bellerochea van H., 1885 Cells in flat chains, touching by valve centres and marginal processes, triangular or ovate in valve, rectangular in girdle view; intercalary bands hard to see; cell wall weakly siliceous. 69. Bellerochea malleus (Brightw.) van H. var. biangulata Hust., 1930. (Plate 34, Fig. 45). van H., 1885, 203. Allen and Cupp, 1935, 144, 78. Triceratium malleus Brightw., 1858b, 154, 8, 6—7. Cells rectangular in girdle view, forming flat, somewhat curved chains, touching at valve centres and margins, in valve view ovate. Breadth, 70μ. Distribution. Australia: Thursday Island; Sandy Cape to Babel Island; St. Vincent Gulf; 60 miles west of Geraldton. Genus Ditylum Bail., 1862 Cell prism-shaped with rounded angles, appearing cylindrical in girdle view, solitary or in pairs; valves with slight marginal processes or rounded, depressed centre and a strong central, hollow spine and a number of spinelets surrounding the central area. 70. Ditylum brightwellii (West) Grun. (Plate 36, Fig. 27). Grun. in van H., 1885, 196. Triceratium brightwellii West, 1860, 149, 7, 6. Ditylum trigonii Bail, 1862, 163. Ditylum inaequale Bail, 1862, 163. Cells prism-shaped, with rounded angles, solitary or in pairs, valve view triangular, with rounded corners; depressed central area with stout, long, hollow, central spine, and surrounded by a row of short spines; marginal areas very finely punctate. Width, 24–60μ. Distribution. Australia: Thursday Island to Maria Island. New Zealand: Hauraki Gulf. Genus Eucampia Ehr., 1839 Cells in curved chains, elliptical in valve view, somewhat H-shaped in girdle view, valve being depressed between processes, which lie on margin.

Key to Species ofEucampia 1. Apertures circular or nearly so E. zoodiacus. Apertures elliptical 2 2. At least one valve obviously punctate E. balaustium. Valve markings faint E. cornuta. 71. Eucampia zoodiacus Ehr. (Plate 36, Fig. 28). Ehr., 1839, 71, 4, 8. Allen and Cupp, 1935, 143, 74. Cells in curved chains united by 2 blunt processes at valve margins; cells flat elliptic-linear in valve view, in girdle view with curved sides, one appearing concave, the other convex; an O-shaped aperture is formed by the valve processes between the two adjacent cells of the chain Width, 40μ. Distribution. Australia: Cape Moreton to Eden, Gordon, Shark Bay; winter-spring form reaching peak in August. New Zealand: Wellington Harbour, Cook Strait. 72. Eucampia cornuta (Cl.) Grun. (Plate 36, Fig. 29). Grun. in Cl. and Grun., 1880, 95b, 5. Allen and Cupp, 1935, 143, 75. Moellena cornuta Cl., 1873b, 7. Differs from E. zoodiacus by having more prominent intercalary bands, and longer, thinner processes forming an oval aperture between the cells; centre of valve more depressed than with E. zoodiacus; valve markings faint. Width, 45μ. Distribution. Sandy Cape to Montague Island, St. Vincent Gulf. Infrequent. 73. Eucampia balaustium Castr. (Plate 34, Fig. 46). Castr., 1886. 97, 18, 5. Hendey, 1937, 285. Cells united to form curved chains; valves elliptical, surface flat, concave or convex, with angles produced forming stout, truncate processes, one produced more than the other; valves punctate, varying greatly in degree of silicification, even in same cell; chromatophores several. Polar axis, 60μ. Distribution. 62° S., 169° E. Recorded from Antarctic by Castracane, Karsten and Hendey. Genus Climacodium Grun., 1868 Cells. in long, straight chains, broader than long, H-shaped, with rectangular apertures between cells, cells very weakly siliceous. Key to Species of Climacodium Apertures barely oval C. frauenfeldianum. Apertures elliptic-lanceolate C. biconcavum. 74. Climacodium frauenfeldianum Grun. (Plate 36, Fig. 30). Grun., 1868, 102, 1a, 24. Allen and Cupp, 1935, 144, 76. Cells in straight chains with oblong apertures between cells; cells flat, with hammer-shaped ends, intercalary bands absent; frustule weakly siliceous. Width, 100μ. Distribution. Australia: Sandy Cape to Babel Island, January to September; maximum in September; sub-dominant at times; indicator of Coral Sea water mass. 75. Climacodium biconcavum Cl. (Plate 36, Fig. 31). Cl., 1897a, 22, 2, 16, 17. Lebour, 1930, 189, 149b. Eucampia heterauloides Ost. in Ost. and Schmidt, 1901, 157, 9. Eucampia biconcava Ost. 1902, 241. Cells almost square in girdle view, chains flat, straight or twisted, apertures elliptic-lanceolate. Width, 50μ. Distribution. East Australian coast, very rare. Genus Streptotheca Shrubsole, 1890 Cells in straight but twisted chains, united by valve faces; in valve view, elongate-elliptical or tripartite; in girdle view, rectangular.

Key to Species ofStreptotheca Cells in valve view bipartite S. thamesis. Cells in valve view tripartite S. indica. 76. Streptotheca thamesis Shrubs. (Plate 36, Fig. 32). Shrubs., 1890, 260, 13, 4–6. Hendey, 1937, 287. Cells in chains twisted about pervalvar axis, united by valves with no aperture; rectangular in girdle view, elliptical, flat in valve view; frustules weakly siliceous. Width, 60μ. Distribution. Australia: Sandy Cape to Maria Island, Gordon. New Zealand: Milford Sound, Hauraki Gulf. 77. Streptotheca indica Karsten (Plate 36, Fig. 33). Karsten, 1907, 395, 46, 8a, b. Allen and Cupp, 1935, 144, 77. Cells in chains, united by valves which have a slight central depression; tripartite in valve view, twisted on pervalvar axis. Dimensions, 200 × 50 × 20μ. Distribution. Australia: Cape Moreton to Jervis Bay, September, January, April; Coral Sea form. New Zealand: Wellington Harbour, Milford Sound. Family Chaetoceraceae Genus Chaetoceros Ehr., 1844 This is the largest genus of truly planktonic diatoms, but it is almost certain that a number of described species are synonymous. Frequently, a single chain will have forms which could be ascribed to two or more species Ch secundum, Ch. curvisetum and Ch. pseudocurvisetum are three species which show such intergrades. However, it seems impossible to resolve these difficulties until the forms can be cultivated, and differences noted in the laboratory with respect to pure cultures. Cells in chains or solitary, oval, rarely round in valve view, in girdle view rectangular with straight sides and concave, flat or convex ends A long seta (bristle or awn) projects from each corner of the cell, and usually anastomoses with or adheres to the seta of the neighbouring cell near the base. Key to the Species of Chaetoceros 1 Chromatophores numerous 2. Chromatophores 1 per cell 22. Chromatophores 2 per cell 19 2. Chromatophores present in coarse setae 3. Chromatophores not in relatively fine setae 16. 3. Setae with hairs 4. Setae smooth 13. 4. Cells solitary 5. Cells in chains 8. 5 Setae bent posteriorly 6. Setae of upper valve directed anteriorly 7. 6. Deep groove between anterior setae Ch peruvianum. Anterior margin of setae continuous with upper valve Ch criophilum 7. Valves with central processes Ch. rostratum. Valves with central spines Ch atlanticum f audax 8. Valves with central processes Ch atlanticum No central process 9. 9. Apertures wide 10. Apertures narrow but obvious Ch boreale Apertures concealed by setae 11. Apertures with clefts between setae Ch concavicorne 10. Setae denticulate at base Ch denticulatum Setae not denticulate Ch erbenn 11. Setae in approximately the same plane 12. Setae radial in valve view Ch. convolutum 12. Valves with slightly raised central area Ch. castracanen Central area of valve not raised, epiphytic. Vorticella normally present Ch coarctum. Central area of valve continuous with anterior setae Ch. criophilum.

13. Cells solitary 14. Cells in chains 15. 14. Setae of even thickness perpendicular to pervalvar axis Ch. danicum. Setae much swollen at base, often twisted together Ch. schimperianum. 15 Apertures not longer than cells Ch. decipens. Apertures longer, often much longer than cells Ch. dichaeta. 16. Setae fused with setae of adjacent cell Ch decipiens. Setae not fused 17 17. Setae of two orders, one fine, straight, the other coarser and twisted Ch. compressum. Setae not of two orders 18 18. Aperture very narrow Ch. teres. Aperture moderate to wide Ch. lorenzianum. 19 Valves with central protuberance 20. Valves without protuberance 21. 20. Protuberance of adjacent valves touching Ch. simile. Protuberance not touching Ch. didymum. 21 Apertures large, rectangular Ch. laciniosum. Apertures smaller, elliptical Ch. vanheurckii. 22 Chains forming spherical colonies Ch. sociale. Chains not forming spherical colonies 23 23. Cells in curved, more or less spirally twisted chains 24. Cells in straight or slightly twisted chains 25. Cells in flexible chains Ch. difficile. 24 Apertures elongated, slightly narrowed in middle Ch. debtle. Apertures oval to rhomboid, broadened in middle Ch. secundum. 25. Setae of 2 orders, stronger setae forked Ch. messanense. Setae of some cells curving round cell Ch. cinctum. Setae uniform (except for terminal setae) 26 26. Setae arising from protuberance of cell Ch. paradoxum. Setae not so arising 27 27. Apertures very narrow to absent Ch. lauderi. Apertures rectangular Ch. diadema. Apertures lanceolate 28 28 Terminal setae much thickened Ch. affine. Terminal setae not strongly thickened Ch. mitra. 78 Chaetoceros affine Lauder (Plate 36, Fig. 34). Lauder, 1864, 68, 8, 5. Gran and Angst, 1931, 479. Ch. schuetti Cl., 1894, 14, 1, 1. Ch. willer Gran, 1897, 10, 4, 47; 1905, 81, 9. Cells in straight chains, rectangular on broad girdle view, with sharp corners; apertures narrow, lanceolate, slightly constricted in the middle; valve mantle high, separated from girdle zone by small notch, setae delicate, terminal setae large, diverging strongly perpendicular to chain axis, then bent parallel to axis, slightly twisted, chromatophores one per cell, with large central pyrenoid. Breadth, 20μ. Distribution. Trial B. to Eden, March-August; East Australian current indicator; Gordon. 79.Chaetoceros atlanticum Cl. (Plate 36, Fig. 35a). Cl, 1873b, 11, 2, 8. Hendey, 1937, 290. Cells in straight chains, rectangular in girdle view, valve mantles deep, constricted at girdle, and with small spine in centre; apertures flat-hexagonal, moderate; setae arising slightly inside cell corners, terminal setae shorter and thicker, bending towards pervalvar axis, spined, chromatophores small, numerous, extending into setae Width, 20–50μ. Distribution. South of New Zealand in Antarctic and sub-Antarctic water. forma audax Gran (Plate 36, Fig. 35b). Gran, 1904. Lebour, 1930, Ch. audax Schütt, 1895, 45, 5, 25. Solitary form, setae more curved, opposed, bending towards each other at ends Distribution Sub-Antarctic.

var. neapolitana (Schröder) Hust. (Plate 36, Fig. 35c). Hust., 1930, 645, 466. Hendey, 1937, 290. Ch, neapolitanum Schröder, 1900, 29, 1, 4. Gran, 1905, 65, 2. Cells elongated; in straight chains, aperture diamond-shaped, almost equal to cell. Width, 20μ. Distribution. Australia: Off Stradbroke Island and Port Hacking; Western Bass Strait. Chaetoceros boreale Bail. Bail., 1855, 8. Hendey, 1937, 292. Cells in short, straight chains, valves slightly convex, elliptical, mantle rather deep, straight, connecting zone narrow; apertures narrow; setae arising within margin and after crossing, almost parallel to each other and perpendicular to pervalvar axis; thickening towards tips, with spines; chromatophores numerous, extending into setae. Diameter, 15–30μ. Distribution. Antarctic water south of New Zealand. 80. Chaetoceros castracanei Karsten (Plate 36, Fig. 36). Karsten, 1905, 116, 15, 1. Hendey, 1937, 295. Cells in chains of 6 to 20, rectangular in girdle view, elliptical in valve view, valves with slightly raised central area, almost touching neighbouring cell; apertures reduced or absent, setae arising at valve corners, spined, except at point of emergence. In our specimens, the setae were almost perpendicular to pervalvar axis and apparently fused throughout length. Terminal setae diverging; chromatophores numerous, extending into setae. Width, 25–30μ. Distribution. Lat. 60° S., 169° E. 81. Chaetoceros cinctum Gran (Plate 37, Fig. 37). Gran, 1897, 24, 2, 23. Lebour, 1930, 163, 125. Cells in straight or slightly curved chains, apertures narrow, constricted in the middle, setae variable in thickness, fairly straight or bent across cell; one chromatophore. Breadth, 15μ. Distribution. Babel Island; June; possibly a temperate or sub-Antarctic form. 82. Chaetoceros coarctatum Lauder (Plate 37, Fig. 38). Lauder, 1864, 79, 88. Allen and Cupp, 1935, 133, 52. Chains straight, ends different; apertures very small; posterior terminal setae very large, strongly curved, heavily spined, anterior terminal setae less robust, curved posteriorly, less heavily spined, setae in middle of chain resembling anterior setae; chromatophores numerous in cells and in setae. Vorticella sp. frequently epontic on this species. Breadth, 40μ. Distribution. Australia: Sandy Cape to Babel Island; St. Vincent Gulf; January to September. New Zealand: Waters north-east of New Zealand, between 28° and 30° S. 83. Chaetoceros compressum Lauder (Plate 37, Fig. 39.) Lauder, 1864, 8, 6. Gran and Angst, 1935, 472, 55. Ch. contortus Schütt, 1895, 43, 15, Gran, 1905, 78. Cells in straight chains, twisted about axis of chain; rectangular in broad girdle view with rounded corners, apertures moderate to narrow, rectangular, constricted in middle; valves convex, setae arising within rim of valve, basal part distinct, outer part perpendicular to chain axis, then bent, delicate except for some pairs often differentiated near centre of chain; these setae often shorter, thickened and twisted, directed towards one end of chain; chromatophores small, 4–20 per cell. Width, 8–20μ. Distribution. Australia: Cape Byron to Babel Island, June to December; Port Fairy, St. Vincent Gulf. A warm water indicator. 84. Chaetoceros concavicorne Mangin (Plate 37, Fig. 40). Mangin, 1917, 704. Gran and Angst, 1931, 469, 50. Ch. peruvianum Vanhoffen, 1897, 260, 3, 5–7. Ch. criophilum Jorgensen, 1901, 20.

Cells in straight chains, rarely solitary; upper valve domed, lower rectangular; apertures clearly visible, elongate, narrow, especially below; setae arising well towards centre of valve, nearer margin in lower valve than in upper, curved towards lower end of chain, strongly spined and containing chromatophores, which are numerous in cell. Width 15–30μ. Ch. peruvianum Brightwell, is very close to this species and may be identical with it, or a solitary variety of it, in which case Brightwell's name would have priority. Distribution. Australia: Port Hacking, Port Jackson, Port Phillip, Roebuck Bay, Scotts Reef, Swan River (West Australia). New Zealand: Off Napier; Antarctic south of New Zealand. 85. Chaetoceros convolutum Castr (Plate 34, Fig. 47). Castr., 1886, 78. Gran and Angst. 1931. 468. C. criophilum Cl, 1901, 20, 1, 6. Cells in slender, straight or passively bent chains, setae in valves view of chain appear to be radially arranged; apertures narrow, hidden by setae; valves unequal, upper arched, lower straight; boundary between mantle and girdle notched; setae strong, arising near centre of upper, nearer margin of lower valve, bending posteriorly, armed with slender spines; chromatophores round, numerous, present in setae Width 10–30μ. Distribution. Australia: Camden Haven to Pedra Blanca; winter form; Bass Strait (common). New Zealand Cook Strait, Wellington Harbour. 86. Chaetoceros criophilum Castr (Plate 34. Fig. 48). Castr., 1886. 78. Hendey, 1937, 295, 13, 7. non C. criophilium Jörgensen, 1901, 20; see Hustedt in A. S, 1921, 342, 1–3. Cells solitary or in short chains, setae in valve view of chain approximately in one plane valves dissimilar, surface almost circular, upper strongly convex with deep mantle, lower almost flat, with shallow mantle; setae of upper valve emerge from centre as part of valve surface those of lower valve emerge nearer margin. both spined and directed posteriorly in even curves chromatophores several Diameter, 40–50μ. Distribution. A characteristic Antarctic diatom South of New Zealand from 63° S. to sub-Antarctic convergence and occasionally north of 42° S, both off Tasmania and New Zealand. 87. Chaetoceros secundum Cl (Plate 37, Fig. 41). Cl., 1873. Ch curvisetum Cl., 1889, 55. Cupp. 1943, 137, 93. Cells in spirally curved chains, rectangular in broad girdle view with conspicuous corners elliptical in valve view; apertures elliptical to circular; setae originate at cell corners, all bent towards outside of curved chain axis; chromatophores large, single, with central pyrenoid Width. 15–20μ. Distribution. Australia: Moreton Bay to Babel Island, Gordon, Shark Bay; frequently dominant in oceanic and estuarine plankton; occurring in peaks in August-September, often common throughout the year New Zealand: Hauraki Gulf, Wellington Harbour. 88. Chaetoceros danicum Cl. (Plate 37, Fig. 42). Cl., 1889, 55. Gran and Angst, 1931, 470, 51. Ch. wighami van H., 1880–1885, 82, 1. Ch boreale Schütt, 1893, 19, 5. Cells small, solitary, round in valve, rectangular in girdle view; mantle high, notched girdle rudimentary; setae arising near valve edge, outside apical plane, extending perpendicular to parvalvar axis, then obliquely towards sides of apical plane so as to form a cross; spiny on outer portion; chromatophores small, numerous, a few present in basal part of setae Width, 10–20μ. Distribution Australia: Moreton Bay to Port Hacking, Lakes Entrance, Port Phillip, Swan River, Shark Bay, Broome New Zealand: Milford Sound, Antarctic (61° 58′ S., 169° E); occurs throughout the year. 89. Chaetoceros debile Cl (Plate 37, Fig. 43). Cl, 1894, 13, 1, 2. Gran and Angst, 1931, 481, 65.

C. vermiculus Schütt, 1895, 39, 7 a–c. Cells in spiral chains, rectangular in broad girdle view, round or oval in side view; apertures long and narrow, hexagonal; setae thin, arising within cell corners, crossing at base and extending outwards from spiral; chromatophores one per cell, with large pyrenoid Width, 10–40μ. Distribution. Australia: Moreton Bay to Port Hacking, July to October; Coral Sea indicator. 90 Chaetoceros decipiens Cl (Plate 37, Fig. 44). Cl, 1873b, 11, 1, 5. Gran and Angst, 1931, 470, 52. Ch. concretus Engler, 1883, 11. Cells in straight chains, rectangular in broad girdle view, with sharp corners touching those of adjacent cells; apertures vary from lanceolate-linear to circular; setae without basal portion, arising at corners of valves perpendicular to chain axis, fusing for some distance with setae of adjacent cells; terminal setae shorter and thicker, directed first obliquely outwards then parallel to chain axis; chromatophores numerous. Width, 25–50μ. Distribution. Australia: Moreton Bay to Eden, Shark Bay, frequent throughout, the year. New Zealand: Cook Strait. 91. Chaetoceros denticulatum Lauder (Plate 37, Fig, 45). Lauder, 1864, 79, 8, 9. Allen and Cupp, 1935, 135, 53. Cells in straight chains, ends different; apertures very small, central, setae arising close to valve centre, at first almost parallel with chain axis, then with an elbow, turning at right angles, with distinct tooth on lower setae; setae with spines; chromatophores numerous Width. 25–30μ. Distribution. Australia: Sandy Cape to Babel Island, Arafura Sea, Torres Strait. 92. Chaetoceros diadema (Ehr) Gran (Plate 37, Fig. 46). Gran, 1897, 20, 2, 16–18; 1905, 84, 102. Ch. lawii Mantguin, 1954, 15. 6, 2. Synedrium diadema Ehr, 1854, 35, 18, 13. Cells in straight chains; valves slightly convex; apertures narrow, rectangular, setae arising slightly within valve margin, almost at right angles to pervalvar axis; chromatophore single Width, 20–35μ. Distribution 62° S, 169° E; rare; recorded from Heard Island by Manguin as Ch. lawii. 93. Chaetoceros dichaeta Ehr. (Plate 37, Fig. 47). Ehr., 1844, 200; 1873, 12, 2, 4. Cupp, 1943, 106, 60. Cells in long, straight chains, more or less rounded; setae arising well inside valve margins, bases at first parallel to chain axis, then strongly diverging and forming long, diamond-shaped apertures; terminal setae parallel with, then diverging and latterly almost parallel with chain axis; chromatophores small, numerous, extending into setae Width 10–15μ. Distribution. St. Helens; Antarctic and sub-Antarctic convergence to 57° S. 94. Chaetoceros didymum Ehr. (Plate 37, Fig. 47a). Ehr., 1845, 45. Gran and Angst, 1931, 474, 57. Cells in chains, four-cornered in girdle view, apertures large, constricted in middle; valves with a semi-conical protuberance in centre, visible in broad girdle view; setae arising from produced ends of cells, crossing as some distance from chain with small mucilage organs at base; chromatophores 2 per cell Width, 10–30μ. Distribution. Australia: Cape Byron to Port Stephens; Swan River; Broome; January to October. 95. Chaetoceros difficile Cl. (Plate 37, Fig. 48). Cl, 1900a, 20, 8, 16–18. Cupp, 1943, 132, 86. Chains straight but loose and phable; cells rectangular in girdle view, apertures moderate, hexagonal to rectangular, valves flat, without notch between mantle and girdle, setae fine,

arising from corners of cell, crossing at some distance therefrom; chromatophore single. Width, 8–15μ. Distribution. Australia: Cape Moreton to St. Helens, Broome to Swan River; all year; commonest in summer; sub-dominant on occasions. 96. Chaetoceros eibenii (Grun.) Meunier (Plate 37, Fig. 49). Meunier, 1913, 15. Gran and Angst, 1931, 467, 48. Ch. paradoxus v. eibenii Grun. in van H., 1880–1885, 82, 9, 10. Chains straight, cells rectangular with rounded corners in broad girdle view; apertures flat, hexagonal; valves without central spine; setae arising near corners, crossing near bases, curved outward from apical plane, outer half nearly parallel to transapical axis, armed with minute spines; valves mantle low, notched; chromatophores small, numerous, extending into setae Width, 30–70μ. Distribution. Australia: Thursday Island, Port Stephens to Eden; Broome to Swan River. Mainly a summer form, often common; rare in May-June. 97. Chaetoceros laciniosum Schütt (Plate 37, Fig. 50). Schütt, 1895, 38, 5 a–c. Gran and Angst, 1931, 476, 58. Ch distans Cl, 1894, 14, 2, 3. Cells in straight chains, rectangular in broad girdle view, corners rounded on outer side; apertures broad, rectangular, with rounded corners, slightly depressed in middle by valve arches; setae thin, basal part parallel to chain axis, then perpendicular thereto and finally parallel; terminal setae differentiated, parallel in broad, diverging in narrow girdle view; chromatophores 2 per cell, lobed, with central pyrenoid. Width, 10–50μ. Distribution. Australia: Port Hacking, St. Helens; May-October. New Zealand: Sub-Antarctic convergence, south of Campbell Island. 98. Chaetoceros lauderi Ralfs (Plate 37, Fig. 51). Ralfs, in Lauder, 1864, 77, 8, 3, 4. Cupp, 1943, 118, 73. Somewhat more delicate than Ch teres, with somewhat twisted chains, cells cylindrical with rounded corners, apertures small or absent; setae delicate or absent, terminal setae parallel to chain axis, intermediate setae at right angles; chromatophore single Width, 20μ. Distribution. Australia: Port Hacking, and east of Jibbon Cape; rare. 99. Chaetoceros lorenzianum Grun. (Plate 38, Fig. 52). Grun., 1863, 157, 14, 13. Gran and Angst, 1931, 471, 53. Ch. cellulosus Lauder, 1864, 78, 8, 12. Cells in straight chains, broad, rectangular in broad girdle view; valves flat or slightly elevated in centre; valve mantle short, girdle zone short; setae delicate, with transverse striae, rising vertically from corners, fused where they leave the chain, and diverging; terminal setae diverging throughout length; chromatophores 4–10, large, plate-like. Width, 20–60μ Distribution. Australia: Sandy Cape to Babel Island, St. Vincent Gulf, Swan River. New Zealand: Auckland Harbour; winter-spring, very common to dominant at times. 100. Chaetoceros messanense Castr (Plate 34, Fig, 48). Castr., 1875, 32, 1, 1a. Cupp, 1943, 133, 89. Cells in straight chains, rectangular, setae emerging from corners, apertures elliptical, varying, usually large, setae more or less parallel, some setae much larger, directed posteriorly anastomosing through half of length, then bifurcating, valves of cells being correspondingly thicker, terminal setae weak, often curved forwards and then posteriorly, often unlike chromatophore single Diameter, 30–50μ. Distribution In warm water west of Bass Strait; May, 1957. 101. Chaetoceros mitra (Bail.) Cl. (Plate 38, Fig. 53). Cl, 1896, 8, 2, 1, 2. Dicladia mitra Bail, 1856, 4, 1, 6. Dicladia gronlandica Cl, 1873b, 12, 2, 10. D. capreolus Ehr., 1854, 18, 101–2.

Cells in straight chains, cylindrical, apertures lanceolate, constricted in middle; setae arising at corners, crossing immediately, slender and short; terminal setae parallel to and converging on chain axis; resting spores common; primary valve mitre-shaped with dichotomous horned processes, secondary valve slightly domed; chromatophores single Width, 20–35μ. Distribution. Australia: Camden Haven to Eden: spring, East Australian current indicator. New Zealand: As Dicladia capreolus by Gr. & St., 1887. 102. Chaetoceros paradoxum Cl. (Plate 38, Fig. 54). Cl., 1873b. 10, 3, 16. Allen and Cupp. 1935, 140, 67. Cells in twisted chains, both valves biconical in broad girdle view, conical in narrow girdle view; notched, somewhat twisted; setae arising from protuberances of cell, anastomosing within valve margin then offset at various angles to pervalvar and transapical axes; chromatophore single. Width, 15–30μ. Distribution. Australia: Sandy Cape to Babel Island; June to September. 103. Chaetoceros pernvianum Brightw (Plate 34, Fig. 49). Brightw.1856, 107, 7, 16–18. Cupp, 1943, 113, 68. Cells usually solitary. rectangular to square in broad girdle view, with rounded corners valves unlike, upper more rounded than lower, distinctly notched at girdle; apertures narrow, upper terminal setae arising near centre of valve, but with definite cleft between them, at first parallel to pervalvar axis, then turning posteriorly and swelling slightly, very long; posterior setae arising nearer valve margin, at an angle to pervalvar axis, almost straight; setae strongly spined; chromatophores numerous, extending into setae Width. 20μ. Distribution. Australia: Stradbroke Island to Babel Island; May to September. A smaller form is endemic and frequently dominant in Lake Macquarie. 104. Chaetoceros postratum Lauder (Plate 38, Fig. 55). Lauder, 1864, 79, 8, 10. Allen and Cupp, 1935, 136. Cells usually solitary, rectangular with rounded corners; valves notched, and with strong central processes; setae arising within valve margin, extending at right angles to pervalvar axis, spined and robust; chromatophores; numerous, extending into setae. Width, 20μ Distribution Australia Trial Bay. Rare. 105. Chaetoceros schimperianum Karsten (Plate 34, Fig. 50). Karsten, 1905, 117, 15, 2, 16, 4. Hendey, 1937, 298, 13, 13–14. Cells solitary or in short chains; valves elliptical, surface flat or slightly concave, setae arise well inside margin, at first oblique, then perpendicular to pervalvar axis, undulating and may cross once or twice, thick at base then rapidly tapering and hair-like, chromatophores numerous, extending into bases of setae. Diameter, 20–25μ. 106. Chaetoceros simile Cl. (Plate 38, Fig. 56). Cl, 1896, 30, 1, 1. Gran and Angst, 1931, 473, 56. Distribution. Antarctic water south of New Zealand. Cells small, in straight chains, broad, rectangular in broad girdle view; apertures small, divided by protuberances of adjacent valves; setae arising at cell corners, directed apically outward, crossing somewhat outside chain, terminal setae slightly thicker, parallel to the rest; chromatophores 2 per cell. Width, 10–15μ. Distribution. Australia: Port Hacking, and east of Jibbon Cape. New Zealand: Hauraki Gulf, Cook Strait. 107. Chaetoceros sociale Lauder (Plate 38, Fig. 57). Lauder, 1864, 77, 8, 1. Gran and Angst, 1931, 486, 70. Ch. wighami Cl and Grun, 1880, 7, 134. Ch lorenzianum v. parvula Grun. in Cl and Grun. 1880, 1c, 7, 138. Cells small, square to rectangular in broad girdle view, corners not touching those of adjacent cells, united into short, slightly bent chains which combine to form spherical mucilaginous colonies; apertures elongated, slightly constricted in middle, setae hair-like, arising within cell corners, with short basal part, three short, the fourth very long and entwined with long setae of other cells, thus holding cells in colonies; chromatophore single Width, 5–12μ. Distribution. Australia: Cape Moreton to Eden.

108. Chaetoceros teres Cl (Plate 38, Fig. 58). Cl, 1896, 30, 7. Gran and Angst, 1931, 472, 55. Cells rather large, in straight chains, rectangular in broad girdle view; apertures very small, lanceolate, valve mantle very low, girdle high, no notch; setae without basal portion, arising at cell corners, perpendicular to chain axis, extending obliquely on either side of apical plane, chromatophores small, numerous. Width 10–40μ. Distribution. Australia: Port Hacking to St Helens; estuarine in Port Jackson, Port Hacking, Lake Macquarie New Zealand: Milford Sound. 109. Chaetoceros vanheurckii Gran. Gran, 1897, 18. Gran and Angst, 1931, 476, 60. Ch. ralfsii van H, 1880–1885, 82, bis, 3. Ch. constrictum Gran in Gran and Thompson, 1930. Cells of moderate size, in straight chains, rectangular in broad girdle view, apertures lanceolate, slightly constricted, valves with concave bases, notched; setae without basal portion, bent acutely towards axis of chain; terminal setae and some subterminal ones strong, with spinules in spirals; other setae slender; chromatophores 2 per cell. Width, 15–40μ. Distribution Australia: Sandy Cape to St Helens. Shark Bay New Zealand: Milford Sound. Other species described from this region are:— C. diversus Cl, 1873. (A S, 1921, 338, 4) New Guinea. C. gastridinium (Ehr) Grun. in v H., 1885 (Gr. & St., 1887). Oamaru. C. pseudocrinitus Ost. v. tropica Hust (in A. S., 1921, 339, 9). New Guinea. C. reichelti Hust (in A. S, 1921, 344, 6) Seeadler Haven, N.G. Goniothecium odontella Ehr (Chaetoceros spores?) Gr. & St., 1887, 71). Oamaru. Stoschia? punctata (Chaetoceios spores?) Gr. & St., 1887, 145 Oamaru. Sub-order Soleniineae Family Bacteriaceae Genus Bacteriastrum Shadb., 1854 Cells in chains, cylindrical; united by fusion of regularly arranged setae which later separate. Terminal setae different. Key to the Species of Bacteriastrum Setae bifuicating B. delicatulum Setae not bifurcating B. varians. 110 Bacteriastrum varians Lauder (Plate 38, Fig. 60). Lauder, 1864, 8, 3, 1–6. Allen and Cupp, 1935, 133, 48. Cells of nearly equal width and length; setae 10–26, at right angles to chain axis, basal part usually shorter than in B. delicatulum; apertures small; terminal setae with fine, small spines arranged in spiral rows. Diameter, 30μ. Distribution Moreton Bay to Eden; autumn to winter. 111 Bacteriastrum delicatulum Cl (Plate 38, Fig. 61). Cl, 1897b, 298, 15. Gran and Angst, 1931, 463. Cells longer than thick, setae 6–12, perpendicular to chain axis, basal part long, with bifurcations far from cell in a plane at right angles to chain axis; and setae spirally arranged bent over like an open umbrella. Diameter, 20μ. Distribution. Australia: Sandy Cape to Babel Island, April-December, often sub-dominant; Broome to Swan River; common in summer months. Family Rhizosoleniaceae Genus Rhizosolenia (Ehr.) em. Brightw., 1858 Cells straight or bent, solitary or in chains. Valves with an excentric tip or fine hair-like projection which, as a rule, corresponds with an imprint on adjoining cell; intercalary bands numerous, shape varying with species.

Key to the Species of Rhizosolenia 1. Valve conical 6. Valves rounded or flat 2. 2. Cells curved, in spiral chains R. stolterforthii. Cells straight 3 3. Spine hair-like 4. Spine large R. cylindrus. 4. Valve rounded-obtuse R. chunii. Valve rounded, irregular R. clevei. Valve flat, with rounded margins 5. 5. Chromatophores large, 2–5 per cell R. delicatula. Chromatophores small, numerous R. fragilissima. 6. Cells curved 7. Cells straight 8. 7. Valves striate from apex to girdle R. robusta. Valves not striate R. curvata. 8. Spine absent R. alata. Spine present 9. 9. Apical spines with two lateral wings R. styliformis. Apical spines not winged 10. 10. Spines long 11. Spines short 12. 11. Spines slightly swollen or not R. hebetata f. semispina. Spines swollen to some distance from base R. setigera. 12 Cells exceedingly broad R. castrcanei Cells narrow or moderate 13. 13. Spines curved and spur-like R. calcur-avis Spines straight 14. 14 Spines blunt 15. Spines sharp R. imbricata. 15. Intercalary bands in two rows R. hebetata f. hiemalis. Intercalary bands in 4 rows R. bergonii. Intercalary bands in more than 4 rows R. acuminata. 112. Rhizosolenia alata Brightw. (Plate 38, Fig. 62a). Brightw, 1858a, 96, 5, 8. Cupp. 1943, 90, 52. Cells cylindrical, straight, solitary or in pairs; valves conical, ending in a slightly bent, truncate process, which, after cell division, rests in a bordered depression in the tip of the adjacent cell; intercalary bands scale-like with a fine, reticulate sculpture arranged in two series with median lines in apical plane; chromatophores small, numerous 10–15μ × up to 1 mm. Distribution. Australia: Sandy Cape to Pedra Blanca, St. Vincent Cape, Scotts Reef to Rottnest Island. Sub-Antarctic; May to October, very common at times. New Zealand: Hauraki Gulf. forma gracillima (Cl) Grun (Plate 38, Fig. 62b). Grun., 1880–1885, in van H., 79, 8. R. alata? v. gracillima Cl., 1881, 26, 6, 78. Like type but narrow (5μ). Intercalary bands narrower. Distribution. Australia: Sandy Cape to Maria Island, Bass Strait, Port Fairy all year. New Zealand: N.E. of Napier, Hauraki Gulf and north of North Island. forma indica (H Perag.) Ost (Plate 38, Fig. 62c). Ost., 1901, 160. Cupp, 1943, 93, 52c. R. indica H. Perag., 1892, 116, 18, 16. Cells much broader than type (15–40μ), intercalary bands broader. Distribution. Australia: Port Hacking New Zealand: Waters south of Dunedin. forma inermis (Castr.) Hust. (Plate 38, Fig. 62d). Hust, 1929, 602, 348. R. inermis Castr., 1886, 71, 24, 7, 8, 10. Differs from type by sharply truncate apices and distinct cleft. Diameter, 10–20μ. Distribution. Antarctic, south of New Zealand.

113. Rhizosolenia acuminata (H Perag) Gran (Plate 38, Fig. 63). Perag., 1892, 110, 15, 4. Cupp, 1943, 94, 53. Cells straight with long, conical, slightly irregular apex; process small with hollow base, intercalary bands scale-like in 4 more rows; chromatophores small, numerous, 180μ to 1 mm. Distribution. Australia: Jibbon Cape to Eden. 114. Rhizosolenia bergonii Perag (Plate 38, Fig. 64). Perag., H., 1892, 110, 15, 5. Cupp, 1943, 81, 43. Cells usually solitary, with cylindrical central portion and long, conical valves; intercalary bands scale-like, usually in 4–5 rows, with regular, bow-shaped margins; imbrication lines distinct; apical processes short, straight, central, hollow truncate; canal swollen at base, bell-shaped at mouth; puncta beginning below apex and diverging; chromatophores small, numerous. 25–50 × 500μ. Distribution. Australia: Sandy Cape to Eden, wide off Babel Island, off King Island (Bass Strait), and in the South Australian gulfs, Arafura Sea. 115. Rhizosolenia calcar-avis Schultze (Plate 38, Fig. 65). Schultze, in Müller, 1858, 339, 13, 5–10. Cupp, 1943, 89, 51. Cells cylindrical, mainly solitary; valves regularly conical, curved at apex; intercalary bands scale-like, rhombic; processes strong, gradually tapering, curved, spur-like, with basal vesicle; chromatophores small, numerous. 10–60μ × up to 1 mm. Distribution. Australia: Thursday Island to Ulladulla (Coral Sea water), St. Vincent Gulf, Swan River to Scotts Reef; a tropical form, very numerous to dominant at times; August to March; north of New Zealand. 116. Rhizosolenia castracanei Perag (Plate 38, Fig. 66). Perag, 1888, 93, 6, 42. Cupp. 1943, 94, 54. Cells cylindrical, solitary, very wide, valves almost flat, with oblique apex, intercalary bands scale-like, moderately flat, rhombic with wavy borders; spine short, blunt, with small basal scales; coarsely punctate 150–400μ × 1–2 mm. Distribution. Australia Sandy Cape to Babel Island. Port Hacking, rare. St. Vincent and Spencer Gulfs, Kangaroo Island, very numerous to dominant; Scotts Reef to Swan River, very numerous to dominant, forming very heavy blooms reminiscent of Antarctic diatom blooms. 117 Rhizosolenia chunii Karsten (Plate 38, Fig. 67). Karsten, 1905, 99, 11, 5. Hendey, 1937, 313. Cells cylindrical, forming short chains, sometimes flattened laterally; frustules straight, almost rectangular: valves almost flat, with short, sharp marginal spine which is difficult to see: connecting zone with 2 lateral lines of intercalary scale-like markings in zig-zag rows Diameter, 30μ. Distribution Antarctic indicator species; south of lat. 60 S. in New Zealand waters. 118. Rhizosolenia clevei Ost (Plate 38, Fig. 68). Ost, 1902, 6. Allen and Cupp, 1935, 128, 34. Cells large, solitary; valves rounded, convex; intercalary bands numerous, scales 5–8 in circumference; apical processes similar to those of R. styliformis, slightly curved with wings less prominent 36–85μ × 280–400μ. Distribution. Australia: Cape Moreton to Port Hacking. Coral Sea form. 119.Rhizosolenia curvata Zacharias (Plate 38, Fig. 69). Zacharias, 1905, 121. Hendey, 1937, 314. Hart, 1937, 413–446, 14. R. curva Karsten, 1905, 97, 11, 2. Cells cylindrical, slightly curved, sometimes crescentic, solitary or in short chains; valves deeply conical, regular, terminated with a sharp spine; spine slender with hollow base; cells weakly siliceous, intercalary markings similar to those of R. styliformis Diameter, 20–60μ.

Distribution. Sub-Antarctic; indicator species recorded by Hendey, Hart, Karsten, Zacharias; was found at lat. 57° 47′-59° 58′ S., 169° 06′ E. together with the warm water forms Planktoniella sol, Biddulphia chinense and Ceratium karsteni. 120 Rhizosolenia cylindrus Cl. (Plate 38, Fig. 70). Cl., 1897a, 24, 2, 12. Cupp, 1943, 80, 42. Cells cylindrical, solitary or in short chains, with convex or rounded valves which may be somewhat sigmoid; cells united by sigmoid processes, not tapering; intercalary bands numerous, ring-shaped, narrowing on both sides; chromatophores small, numerous. Size, 7–14μ × up to 300μ. Distribution. Australia: Shoalhaven to Eden. East Australian current form: also in sub-Antarctic water south of New Zealand. 121.Rhizosolenia delicatula Cl. (Plate 39, Fig. 71). Cl., 1900, 28, 11. Gran, 1905, 48, 52. Cells cylindrical; valves flat, rounded only at margins, with a short, excentric, thin spine fitting into a groove in the adjoining cell; chromatophores large, few, thus differing from R. fragilissima Bergon. Dimensions, 15 × 50μ. Distribution. West of Bass Strait associated with warm water forms. 122.Rhizosolenia fragilissima Bergon (Plate 39, Fig. 72). Bergon, 1903, 49, 1, 9–10. Cupp, 1943, 80, 41. Cells cylindrical, in chains, with blunt, rounded ends; intercalary bands collar-like, but difficult to see; small spine near valve centre fitting into depression in neighbouring cell; chromatophores small plates, numerous. Size 15 × 50μ. Distribution. Maria Island; May. 123.Rhizosolenia hebetata (Bail.) emend. Gran. Bail., 1856, 1, 18–19. Gran, 1904, 524. A dimorphic species. forma hiemalis Gran (Plate 39, Fig. 73a). Gran, 1904, 527, 17, 9–12. Cupp, 1943, 88, 50a. Cells straight, solitary or in pairs, cylindrical, extended; valves tapering; intercalary bands scale-like, alternating; processes thick, blunt, with basal vesicle and fine tube; puncta distinct, chromatophores numerous. Size 18 × 100μ. Distribution. Sydney to Pedra Blanca, Storm Bay, Cape Northumberland, Antarctic and sub-Antarctic; a winter form, characterising the Tasmanian-Bass Strait water mass, derived from Antarctic waters. New Zealand: Hauraki Gulf, Wellington Harbour, east of Napier. forma semispina (Hensen) Gran (Plate 39, Fig. 73b). Gran, 1904, 527. Cupp, 1943, 88, 50b. R. semispina Hensen, 1887, 84, 5, 39. Valves longitudinally drawn out, narrower than f. hiemalis; cell walls more delicate; processes hollow at base, extending as a long, curved hair-like spine. Width, 10μ. Distribution. Australia: Sandy Cape to Jervis Bay (Coral Sea water); Broome, Roebuck Bay; north of New Zealand on latitude 29° S., Hauraki Gulf. 124.Rhizosolenia imbricata Brightw. (Plate 39, Fig. 74a.). Brightw., 1858a, 5, 6. Allen and Cupp, 1935, 129, 35. Cells cylindrical, solitary or in short chains; valve continuing parallel with pervalvar axis into spine on one side, tapering or sigmoid on opposite side; intercalary bands imbricate, striate. punctate; processes short, straight in lateral, wedge-shaped in dorsal view with 2 small lateral wings. Width c. 50μ.

Distribution. Australia: Sandy Cape to Maria Island, St. Vincent Gulf; a summer, warm water form. v. shrubsolei (Cl.) Schröder (Plate 39, Fig. 74b. Schroder, 1906, 346. Allen and Cupp, 1935, 129, 36. R. shrubsolei Cl, 1881, 26. Cells long, narrow, cylindrical; valves more gently tapering than in type form; sculpturing finer than in type. Distribution. Sandy Cape to Pedra Blanca; Cape Liptrap; summer form; New Zealand waters. 125.Rhizosolenia robusta (Norman MS.) Ralfs (Plate 39, Fig. 75). Ralfs, in Pritch., 1861, 866, 8, 42. Cupp, 1943, 83, 46. Cells usually solitary, fusiform, sigmoid or cylindrical, with curved and tapered valves; intercalary bands robust, numerous, annular; distinct longitudinal lines in valve radiating from apex; processes excentric, with hollow base and ending as a hair, chromatophores numerous, close to cell wall Size, 50–150μ × 0.5–1 mm. Distribution. Australia: Cape Moreton to Port Hacking (Coral Sea water), Port Fairy, King Island (presumably West wind drift); Swan River; June to November. This species is frequent in spring blooms in Port Hacking, where it is usually co-dominant with Coscinodiscus grani. Recorded from Australia by Ralfs. New Zealand: Off Napier. 126.Rhizosolenia setigera Brightw, (Plate 39, Fig. 76). Brightw., 1858a, 95, 5, 7. Cupp, 1943, 8, 49. Cells cylindrical, solitary or in pairs; valves conical; intercalary bands scale-like, usually hexagonal or diamond-shaped, processes very long, thickened to some distance from base, or with a very fine canal, and ending in a long, hair-like spine; chromatophores small, numerous, elliptical. Diameter, 6 to 20μ. Distribution. Australia: Thursday Island to Eden, Swan River; winter and spring with a maximum in August-September; south of New Zealand (Lat. 53°–59° S. with R. curvata in sub-Antarctic convergence). 127.Rhizosolenia stolterforthii Perag. (Plate 39, Fig. 77). Perag., H., 1888, 82, 6, 44. Cupp, 1943, 83, 45. Cells cylindrical, curved, united in chains to form a spiral; ends blunt, rounded corners; strong, excentric spine fits into corresponding groove of adjacent cell; intercalary bands collar-like, numerous, not readily seen; chromatophores small, numerous. Width, 8 to 25μ. Distribution. Australia: Sandy Cape to Eden; St. Vincent Gulf, Swan River, Shark Bay, Bass Strait (Western end); waters off North Island of New Zealand. 128.Rhizosolenia styliformis Brightw. (Plate 34, Fig. 32). Brightw., 1858a, 5, 5. Cran and Angst, 1931, 460, 42. Cells cylindrical, usually solitary; valves obliquely pointed, with one side continuous with cylindrical portion of cell, intercalary bands scale-like, finely reticulate, processes pointed, with a long cavity reaching valve tip, and two wings beginning in valve and finishing near base of process; distinct mark in valve for valve of sister cell; chromatophores numerous. Diameter, 20–100μ. Distribution. Cape Moreton to Babel Island, Cape Otway and Burnie (West wind drift), Scott's Reef to Broome; north of New Zealand. Dominant at times, especially off N.W. Australia and occasionally north of Port Fairy. Spring and summer form. Also in Antarctic waters. var. longispina Hust. (Plate 39, Fig. 78a). Hust., in A. S., 1914, 316, 5–7, 12. Cupp, 1942, 87, 48b. Differs from type in longer process, becoming thinner and spine-like. Distribution. Australia: Port Stephens, Eden; St. Vincent Gulf.

v. latissima Brightw, (Plate 39, Fig. 78b). Brightw., 1858a, 5, 5e. Allen and Cupp, 1935, 130, 40. Diameter greater than type–about 100μ, intercalary bands flatter. Distribution. Australia: Moreton Island to Eden; St. Vincent Gulf, Spencer Gulf, east of Kangaroo Island; in February. Genus Guinardia H. Perag., 1892 Cells cylindrical, longer than broad, with straight or slightly curved pervalvar axis, single or in close chains; intercalary bands numerous; valves circular, surface flat, with an asymmetrical, lateral, rudimentary tooth at margin; chromatophores numerous. 129.Guinardia flaccida (Castr.) Perag. (Plate 39, Fig. 79). Perag., H., 1892, 107, 13, 3, 4. Cupp, 1943, 78, 40. Rhizosolenia? flaccida Castr., 1886, 74, 29, 4. Cells typically cylindrical, 1½ times longer, than broad, single or united in chains by whole valve surface; valves very slightly concave, with an irregular tooth at margin; cells weakly siliceous, collapsing when dry; without visible sculpturing; chromatophores small. Diameter. 30–50μ. Distribution. Australia: Thursday Island to Babel Island, St. Vincent Gulf, Encounter Bay, Broome to Swan River; all year; warm water form. New Zealand: Hauraki Gulf. Family Leptocylindraceae Genus Leptocylindrus Cl., 1889 Cells long, cylindrical, united into chains by whole valve surface; valves flat, without spines or processes; intercalary bands present but very difficult to see, frustules thin-walled hyaline, chromatophores many rounded plates or granules. 130.Leptocylindrus danicus Cl. (Plate 39, Fig. 80). Cl., 1889, 54. Cupp, 1943, 78, 39. Cells cylindrical, united in chains by whole valve surface, often only one cell wall between adjacent cells. Diameter, 6–10μ. Distribution. Australia: Sandy Cape to Cape Everard, Storm Bay, Swan River to Albany; western end of Bass Strait; sometimes sub-dominant. New Zealand: Milford Sound; fresh water, Wellington water supply (Wainui) as dominant, Wellington Harbour. Genus Dactyliosolen Castr., 1886 Cells cylindrical, solitary or in stiff chains united by valve surfaces, valves circular, without spines or processes, but with small nodules at margin at times; intercalary bands numerous, semi-annular, with interdigitating ends; surface areolate. 131.Dactyliosolen mediterraneus Perag. (Plate 39, Fig. 81). Perag., H., 1892, 104, 13, 8, 9. Gran and Angst, 1931, 457, 37. D. tenuis Gran, 1905, 25. Cells 2 to 5 times as long as wide, united in chains by valve surface; intercalary bands with delicate, reticulate sculpture, one row of poroids on each. Diameter 15–25μ. Distribution. Australia: Trial Bay, Camden Haven. 132 Dactyliosolen antarcticus Castr. (Plate 39, Fig. 82). Castr., 1886, 75, 9, 7. Hendey, 1937, 323, 6, 1. Cells solitary or in chains united by ends of cells, valves flat or nearly so, connective zone consisting of numerous intercalary bands arranged so that the ends form a spiral about the pervalvar axis; each intercalary band bears a line of oval or elongated puncta, with one rounded and one square end; chromatophores several Diameter, 30–50μ. Distribution. Antarctic, south of New Zealand.

Family Corethronaceae Genus Corethron Castr., 1886 Cells solitary, cylindrical; valve arched, bearing a crown of long, thin setae at their rim; intercalary bands numerous, often very indistinct. 133.Corethron criophilum Castr. (Plate 39, Fig. 83). Castr., 1886, 85, 21, 14. Hendey, 1937, 7, 8. Hendey considers Corethron to be a monospecific genus, and our evidence supports this; the description is covered by the generic description. There is a wide range of variation in this organism, and considerable intergradation as Hendey has shown. Distribution. Common in Antarctic and Sub-Antarctic waters extending northward west of Bass Strait, also in the east Australian region and Arafura Sea. Family Hemidiscaceae Genus Hemidiscus Wallich, 1860 Cells usually solitary, semicircular in valve view, wedge-shaped in girdle view—i.e, cell is shaped like a section of an orange. 134.Hemidiscus cunieformis Wallich (Plate 34, Fig. 53). Wallich, 1860, 42, 2, 3–4. Hendey, 1937, 264. Euddia cunieformis Schütt, 1896, 100. Cell in valve view semicircular, ventral margin almost straight, slightly convex medially; girdle simple; valve structure consists of fine puncta radiating from centre of valve, arranged somewhat as in Coscinadiscus excentricus; small apical protuberances present. Hendey, 1937, considers that there is only one oceanic species of Hemidiscus, which is very variable. Width, 50–100μ. Distribution. E. of Port Hacking, lat. 34° S.; in waters north of New Zealand. Recorded from Oamaru by Grove and Sturt, 1886, 11, are:— H. janischii Green, in v H., 1885. H. striata Gr. & St., 1886. Family Coscinodiscaceae Genus Gossleriella Schütt, 1893 Cells discoid, solitary; valves convex or slightly flattened, without visible structure but with a corona of stout, often spirally twisted marginal bristles arising from small nodules around the edge of valve, between these bristles is an inner row of finer bristles, and an inner corona may arise from centre of valve; chromatophores numerous. 135 Gossleriella tropica Schütt (Plate 32, Fig. 54). Schütt, 1893, 20, 7. Hendey, 1937, 258. Description as for genus. Diameter, 200μ. Distribution. East of Port Hacking, lat. 34° S., in July, 1957. The following additional genera have been recorded by previous authors as occurring in the Australasian region:— Genus Actinocyclus Ehr., 1837 This synonymy of A. ehrenbergi includes about 123 “species”, and there is some doubt as to whether there is more than one species of this genus. A. barklyi Coates, 1861. (A. fuscus Norman.) Type loc. Yarra Yarra. A. ehrenbergii Ralfs in Pritch., 1861 (Petit, 1877) Lyall Bay. A. fuscus Norm, (see A. barklyi Coates). A. moniliformis Ralfs. in Pritch., 1861. (Petit, 1877.) Lyall Bay, Foveaux Strait. Genus Actinodiscus Grev., 1863 A. barbadensis Grev., 1863. (Gr. & St., 1887, 64; A. S., 1888, 132, 1.) Oamaru. A. grayi Gr. (A. S., 1893, 184, 1). Oamaru.

A. maculatus Gr. & St., 1886. (A. S., 1888, 132, 21.) Oamaru. A. tenera Gr. & St. (A. S., 1888, 132, 12). Oamaru. A. vulgaris var. Gr. & St. (A. S., 1888, 132, 17). Oamaru. A. wittianus Gr. & St. (A. S., 1888, 132, 24). Oamaru. Genus Anthodiscus Gr. & St., 1887 A. floreatus Gr. & St. (Gr. & St., 1887; A. S., 1890, 162). Oamaru. Genus Arachnoidiscus Ehr., 1849 A. ehrenbergii Bail. ex Ehr., 1849 (Gr. & St., 1887, 66) Oamaru. A. indicus Ehr., 1854. (Gr. & St, 1887, 66) Oamaru. Genus Brightwellia Ralfs in Pritch., 1861 B. pulchra Grun. in v H., 1885, 128, 9. (= B. coronata Brightw.) Ralfs, 1861 (Gr. & St., 1887, 67.) Oamaru. Genus Clavicula C. aspicephala Pant., 1886–1892. (Gr. & St., 1887.) Oamaru. Genus Cosmiodiscus Grev. C. elegans Grev. v. inermis Pant. (A. S., 1902, 229, 1.) Torres Strait. Genus Craspedodiscus Ehr. fragment. (Ehr., 1869). New Zealand. Genus Craspedoporus Grev., 1863 C. elegans Gr. & St., 1887 (= Porodiscus interruptus according to Weissflog. quoted by Rattray, 1888). Oamaru. Genus Eupodiscus Ehr., 1844 em. Ratt., 1888. E. minutus (Hantzsch) Rab., 1863. (Petit, 1877.) Lyall Bay. (Is an Actinocyclus according to Ratt. 1888, 915.) E. oamaruensis (Gr. & St.) Ratt., 1888. (Glyphodiscus oamaruensis Gr. & St.). (Gr. & St., 1887.) Oamaru. E. scintillans A. S., 1875 (Glyphodiscus s. Gr. & St., 1886). Oamaru. E. stellatus Grev., 1865. (Glyphodiscus st. Grev., 1862; Gr. & St., 1886). Oamaru. E. tenellus Breb., 1857. (Petit, 1877.) Lyall Bay. (Is an Actinocyclus according to Ratt, 1888, 915.) Genus Huttonia Gr. & St., 1887 H. alternans Gr. & St. (Gr. & St., 1887, 142) Oamaru. H. virgata Gr. & St. (Gr. & St, 1887, 142). Oamaru. Genus Isodiscus Ratt., 1888 I. debyi (Gr. & St.) Ratt., 1888. (Lampriscus debyi Gr. & St., 1887, 138.) Oamaru. I. mirificus Ratt., 1888. (Ratt., 1888, 920.) Oamaru. Genus Liradiscus L. ovalis Grev., 1865 (Gr. & St, 1887.) Oamaru. Genus Monopsia Gr. & St., 1887 M. mammosa Gr. & St. (Gr & St, 1887, 142). Oamaru. Genus Porodiscus Grev., 1863 P. hirsutus Gr. & St., 1887. (Gr. & St, 1887, 143; A. S, 1890, 10, 11.) Oamaru. P. interruptus Gr. & St, 1887 (see Craspedoporus elegans). Genus Pseudauliscus Ratt, 1888 Auliscus (Pseudauliscus) notatus Grev, 1865 (Gr. & St., 1886, 10.) Oamaru. P. anceps Ratt, 1888, 907. (Auliscus grovei Cl. MS, Ratt., 1888, 907). Oamaru. P. diffusus Ratt. (Ratt., 1888, 907). Oamaru.

Genus Pyxilla The organisms ascribed to this genus are spores of Rhizosolenia. Ehrenberg's type species, R. americana was transferred to Pyxilla by Grunow (in v H., 1885); Pyxilla thus became a synonym for Rhizosolenia. Howevei, as R. americana is a stage of the recognized rhizosolenias, the generic name is valid. We have listed the following forms under Pyxilla as they cannot be ascribed to a species of Rhizosolenia. P. aculeifera Grun. in v H., 1885. (Gr. & St., 1887.) Oamaru. P. dubia Grun. in v H., 1885. (Gr. & St., 1887.) Oamaru. P. johnsoniana Grev, 1865a (Gr. & St., 1887). Oamaru. P. reticulata Gr. & St. (Gr. & St., 1887, 415). Oamaru. Genus Stephanodiscus Ehr., 1845 S. novae zeelandica Cl, 1894. (A. S., 1901, 225, 22–23.) Oamaru. Genus Stephanogonia Ehr. S. danica (Kitt.) Grun. (Gr. & St., 1887). Oamaru. Genus Stictodiscus Grev., 1861 S. californicus Grev., 1861. (A. S., 1888, 131.) Oamaru. v. areolata Grun., 1884. (A. S., 1888, 131.) Oamaru. v, nitida Gr. & St., 1887. (A. S., 1888, 131.) Oamaru. S. hardmanianus Grev., 1865. v. megapora Gr. & St. (Gr. & St., 1887, 66). Oamaru. S. kittonianus Grev. (A. S., 1888, 131). Oamaru. S. nitidus Gr. & St. (A. S., 1893, 202, 4). Oamaru. S. novae zeelandica Grun. (A. S., 1888, 131). Oamaru. S. parallelus v. gibbosa Gr. & St. (Gr. & St., 1887; A. S., 1888, 131). Oamaru. Genus Stoschia Grun. in v H., 1885 S. punctata Gr. & St., 1887 is probably a Chaetoceros spore. Diatoms as Indicators of Water Movements Wood (1954) showed that dinoflagellates were very useful as indicators of water movements. Using these organisms he was able to suggest the existence of two water masses influencing the composition of the phytoplankton south of Trial Bay, both derived from tropical regions, and also the presence at times of a warm-water flora west of Bass Strait. Both these suggestions have since received confirmation by recent collections from F.R.V. “Derwent Hunter” (see reports). The diatoms also provide some useful indicator species. The more northerly water mass, referred to by Wood (1954) as the Coral Sea water mass is indicated by the following species:—Chaetoceros coarctatum, Ch. debile, Bacteriastrum delicatulum, Rhizosolenia calcar-avis, R. castracanei, R. clevei, R. robusta (also a neritic form), R. styliformis, Detonula confervacea, Stephanopyxis, palmeriana, Biddulphia mobihensis, Hemiaulus hauckii, Climacodium frauenfeldianum, Streptotheca thamesis, S. indica. The species which are of tropical origin and do not appear in waters north of Trial Bay are regarded as indicators of the East Australian current. These include Chaetoceros affine, Ch compressum, Ch. convolutum, Ch. dichaeta, Ch. didymum, Ch. mitra, Rhizosolenia cylindrus, Stephanopyxis turris, Thalassiosira rotula, Th. condensata, Th. baltica, Th. subtilis. Some of these species persist in the mixed water derived from these two sources, but others disappear from the plankton as the water moves south—e.g., Ch. debile, Ch. mitra, R. robusta, which disappear from the plankton between Port Hacking and Bass Strait. The cool-temperate waters of Tasmania and Bass Strait have as indicators Chaetoceros concavicorne and Rhizosolenia hebetata f. hiemalis.

An interesting feature of the east coast diatom plankton was the failure of 14 species common off Eden to appear between there and Babel Island, though 12 of these species reappeared at Babel Island. The stations occupied in this area were one on the edge of the continental shelf and one 100 miles east of it. The phytoplanktological evidence suggests a current anomaly in this region—e.g., vertical mixing. In the Southern Ocean, the presence wide of Port Fairy and west of King Island of a water mass with tropical phytoplankton characters was suggested by Wood (1954). This was tentatively designated West Wind drift, and the diatom indicators of it are Chaetoceros convolutum, Ch. messanense, Rhizosolenia robusta, R. styliformis, and R. styliformis v. latissima. It will be noticed that these indicators differ from those of the eastern water masses, and from those of the South Australian Gulf region which are Rhizosolenia castracanei and R. bergonii. Owing to the limited number of samples available for study it is impossible to evaluate the contribution of West Wind drift and of the South Australian Gulf region to the waters west of King Island. Tropical Indian Ocean water is indicated by Rhizosolenia alata, R. styliformis, R. calcar-avis, Bacteriastrum delicatulum, Chaetoceros eibenii, and Ch. didymum. All these species are recorded from the Java Sea by Allen and Cupp (1935). Ch. eibenii, Bacteriastrum delicatulum, and Rhizosolenia calcar-avis may be found in the Swan River in the summer. In the vicinity of Jurien Bay there are, at times, dense blooms of R. castracanei, of similar density to those of other Rhizosolenia species occurring in Antarctic waters, and far denser than any recorded from the east coast of Australia. The phytoplankton from stations south of New Zealand agreed well with the Antarctic and sub-Antarctic phytoplankton described by Hendey (1937). The occurrence of the normally warm water species Biddulphia chinensis and Planktonella sol at lat. 57° 47′ S., 169° 06′ E. on 31.12.1956 is noteworthy. The latter species has previously been recorded from unexpectedly cool water on other occasions. Rhizosolenia curvata is, as Hendey points out, a characteristic indicator species for the sub-Antarctic convergence. The New Zealand oceanic phytoplankton is characterized by a greater abundance of Coscinodiscus, especially C. centralis and C. excentricus, than occurs in Australian waters; one or both of these species is usually present in catches from the east or west coasts of New Zealand, and north towards Fiji; C. centralis was found as far south as 65° S. C. excentricus to 46° S. Chaetoceros coarctatum which is abundant at times in eastern Australian waters is also numerous between 170° and 173° 24′ E., by 28° 53′-30° 28′ S., with a flora similar to that of the east Australian water masses. It is safe to predict that an ecological study of the diatoms of the Tasman Sea will be of assistance in interpreting the movement and origin of water masses in this region, and possibly in indicating the origin of mixed waters. In the northern Pacific, Thalassiothrix longissima and Nitzschia seriata appear to be indicators of the Oroshio, and Climacodium and Hemiaulus species of the Kuroshio current, and there is considerable overlap of the species in the convergence (mimeographed data from Central Met. Observatory, Japan). While Th. longissima is much larger and more frequent in Antarctic waters than it is farther north, it does occur in warmer waters in the Tasman, and Nitzschia seriata is frequently dominant in waters off Port Hacking, associated with warm water forms. It would appear then that the same species may have somewhat different temperature limits in the northern and southern hemispheres. N. seriata has also been recorded by Allen and Cupp (1937) from the Java Sea and by Subrahmanyan (1946) from the Madras coast. Climacodium and Hemiaulus are associated in Japanese and Australasian waters with warm currents.

Seasonal Variation of the Planktonic Diatom Flora of Port Hacking The diatoms in Port Hacking do not give as clear a picture of water movements as the dinoflagellates do, but, on the whole, they confirm the interpretation of the movements made by Wood (1954), and give us some information of conditions when dinoflagellates were absent. The studies on Port Hacking between 1940 and 1950 are discussed in the following paragraphs. 1940: There was a diatom maximum in April, consisting largely of epontic forms (Licmophora flabellata, Synedra spp.) with some planktonic species (Bacteriastrum delicatulum, Climacodium frauenfeldianum, Stephanopyxis turris) in the lower reaches. This suggests an invasion of marine forms (mixed Coral Sea and East Australian indicators) into the mouth of the port at this time. In July to September, oceanic and neritic planktonic forms were collected as far up as Audley (the limit of marine influence), and there was a maximum deminated by Nitzschia seriata in October. The continuation of the winter phytoplankton maximum into the spring suggests that conditions in the port were more favourable for the continued reproduction of diatoms than for the dinoflagellates. 1941: Marine forms did not reach Audley this year, although the marine dinoflagellate Goniodoma polyedricum did. In April, the maximum consisted of epontic forms (Licmophora flabellata), and oceanic species (Rhizosolenia castracanei, R, alata, R. styliformis, Climacodium frauenfeldianum) occurred with the ubiquitous Chaetoceros secundum in December. This suggests that the oceanic influence indicated by the dinoflagellates in October-November continued into December. 1942: The oceanic diatom peak continued through January into February with Rhizosolenia styliformis, R. stolterforthii, Bacteriastrum delicatulum, Planktoniella sol in January and R. castracanei, Streptotheca thamesis, Ditylum brightwellii in February. In July to September, Stephanopyxis turris, R. castracanei and Planktoniella sol represent oceanic influence, but the estuarine neritic Chaetoceros secundum and Coscinodiscus granii were also present. In December, there was a maximum of the estuarine-neritic Rhizosolenia robusta with C. granii. 1943: In this year, there was only a slight diatom peak, at the entrance in January, the phytoplankton consisting mainly of the dinoflagellate Ceratium buceros. In April, Rhizosolenia alata, and R. styliformis (oceanic forms) were numerous, and in August, the oceanic Stephanopyxis turris (East Australian current) appeared with Chaetoceros secundum, which, although ubiquitous, appears also to be autochthonous in Port Hacking. In November-December, Coral Sea influence is suggested by a peak of Rhizosolenia calcar-avis, R. alata, R. styliformis, R. stolterforthii and Streptotheca thamesis. 1944: In February, Rhizosolenia robusta, R. styliformis and Stephanopyxis turris formed a peak. The two latter species suggest an incursion of mixed oceanic water at that time. Between August and October, there was a prolonged peak of Chaetoceros spp. including C. compressum, C. affine, C. decipiens and C. secundum, the first two indicative of East Australian current water. The usual Rhizosolenia peak occurred in December. 1945: The Rhizosolenia peak continued into January, and in April, a local bloom of R. robusta occurred. In August, epontic species (Licmophora, Synedra) formed a peak. 1949: Tow nettings were resumed in May, having been suspended since 1945. In July, Chaetoceros secundum, Asterionella japonica, Ditylum brightwellii, Skeletonema costatum and Thalassiosira rotula occurred. The last species may have been allochthonous, but it is easily cultured, and could have persisted in the port for some time. Diatoms were numerous from August through to December, starting with Schroederella delicatula and Asterionella japonica, changing to Chaetoceros spp. and Rhizosolenia spp. in October-November.

1950: In this year peaks occurred in January (Ditylum brightwellii and Chaetoceros spp.), March (autochthonous Ch. secundum and Asterionella japonica), July (Ch. secundum, D. brightwellii, A. japonica and Coscinodiscus granii), August-September (D. brightwellii, Ch, secundum, Thalassiosira rotula and Biddulphia mobilensis). L. H. Crosby, E. J. Ferguson Wood, M.Sc., B. A., Division of Fisheries and Oceanography, C.S.I R.O, Cronulla, New South Wales. Index. Diatoms—Part I. Actinocyclus, 525 Hemiaulus, 509 Actinodiscus, 525 Hemidiscus, 525 Actinoptychus, 498 Huttonia, 526 Anthodiscus, 526 Hyalodiscus, 489 Arachnoidiscus, 526 Isodiscus, 526 Asterolampra, 501 Isthmia, 508 Asteromphalus, 502 Lauderia, 494 Aulacodiscus, 499 Leptocylindrus, 524 Auliscus, 500 Liradiscus, 526 Bacteriastrum, 519 Lithodesmium, 509 Bellerochea, 510 Melosira, 488 Biddulphia, 503 Monopsia, 526 Brightwellia, 526 Planktoniella, 498 Cerataulina, 502 Porodiscus, 526 Chaetoceros, 512 Pseudauliscus, 526 Charcotia, 498 Pyxcidicula, 497 Clavicula, 526 Pyxilla, 527 Climacodium, 511 Rhizosolenia, 519 Corethron, 525 Schroederella, 494 Coscinodiscus, 494 Skeletonema, 492 Cosmiodiscus, 526 Stephanodiscus, 527 Dactyliosolen, 524 Stephanogonia, 527 Detonula, 492 Stephanapyxis, 491 Ditylum, 510 Stictodiscus, 527 Eucampia, 510 Stoschia, 527 Eupodiscus, 526 Streptotheca, 511 Gossleriella, 525 Thalassiosira, 492 Guinardia, 524 Triceratium, 505