Environmental Factors Affecting the Life History of Three Soil Species of Colpoda (Ciliata). By J. D. Stout 1165–1188 Parthenogenesis in New Zealand Stick Insects. By J. T. Salmon 1189–1192 Palombiella stephensoni Westblad, a Marine Triclad from Banks Peninsula, New Zealand. By F. R. Nurse 1193–1194 PROCEEDINGS Annual Meeting, 1954 i–xlv Half-yearly Meeting xlv–lxvii OBITUARY Hugh William Segar, M.A., F.R.S.N.Z. 1195–1197 APPENDIX Appendix 1199–1209 INDEX Index to Vol 82 1211–1219 Volume 82, Part 4 Record of Previous New Zealand Science Congresses 823 Participating Bodies and Officers 824 Presideential Address 827 Public Lecture—Science and Mankind 837 Public Lecture—The Struggle Against Equilibrium: A Physico-Chemical Problem in Life 851 Section A.—Chairman's Address 861 Symposia and Sectional papers 870 Section B.—Chairman's Address 871 Symposia and Sectional papers 891 Section C.—Chairman's Address 893 Symposia and Sectional papers 902 Section D.—Chairman's Address 903 Symposia and Sectional papers 907 Section E.—Chairman's Address 909 Symposia and Sectional papers 912 Section F.—Chairman's Address 913 Symposia and Sectional papers 921 Section G.—Chairman's Address 923 Symposia and Sectional papers 925 Section H.—Chairman's Address 927 Symposia and Sectional papers 936 Section J.—Chairman's Address 937 Symposia and Sectional papers 937 Section K.—Chairman's Address 939 Symposia and Sectional papers 946 Section L.—Chairman's Address 947 Symposia and Sectional papers 959 Section M.—Chairman's Address 961 Symposia and Sectional papers 971 Excursions 972

List of Plates Caption Plate number Fig. 1.—North Range (2,120 feet) showing hog-back ridges of resistant Lower to Middle Triassic meta-andesitic tuffs It is separated by a broad belt of siltstones from white Hill (Kaihikuan and higher stages) to the left View looking N. N. W. Fig. 2.—Spheroidal quartz-albite-adularia metasomatite showing concentric veining, in laumontitized tuff Bed NR2 North Range. Fig. 3.—Steeply dipping bed of laumontitized ash 10 feet thick. with detached joint blocks littering slope to the right NR5, North Range. Plate 1 Fig. 1.—Granular mosaic of quartz (low relief) replacing laumontite (strong negative relief and good cleavage) 8784. NR5,, North Range Ordinary light, X150. Fig. 2.—Aggregate of pumpellyite (dark grey) in metasomatite Secondary quartz (colourless) and feldspars (light grey) preserve ghost-like traces of ash structure 8818, NR2,, North Range Ordinary light, X100. Fig. 3.—Icositetrahedral pseudomorphs of feldspars after analcime set in quartz 8824, NR2,, North Range Ordinary light, X100. Fig. 4.—Contact between laumontitized tuff (light) and quartz-albite-adularia metasomatite (dark) Dark streaks of quartz and adularia occur in laumontite near the contact and roughly parallel to it 8799, NR2,, North Range Almost natural size. Plate 2 Fig. 1.—Tuffaceous greywache Meta-anlesitic rock debris and loose crystals of albitized plagroclase and rarer augite in a base rich in chlorite and leucovene 8932 NR3,, North Range Ordinary light, X29. Fig. 2.—Fine rhvodacite vitric tuff Small cuspate glass particles have devitrified to heulandite. often darkened with non oxides A large clear crystal of andesine is near the top and smaller fragments are in the groundmass 9035. 100 feet below top of Oretran Wether Hill Ordinary light, X23. Fig. 3.—Quartz-albite adularia metasomatite showing some large lapilli (dark) cut by anastomosing veinlets secondary feldspar NR2, North Range X4/3. Fig. 4.—Felt of secondary albite in metasomatite, with a few large albitized plagioclase fragments 8814. NR2, North Range Crossed nicols. X90. Plate 3 Fig. 1.—Rubber cast of interior of right valve from holotype. Fig. 2.—Natural internal mould, holotype, lateral view showing muscle impressions. Fig. 4.—Cross section at posterior third, showing thick shell, deformed by compaction of enclosing lock. Fig. 5.—Natural internal mould, holotype, dorsal view showing muscle impressions and taxodont hinge. Figs. 6-9.—Rubber casts from holotype, dorsal, anterior and lateral views. Palacouerlo aft. mundeni Fleming n.sp. Fig. 3.—Rubber cast of interior of left valve. G. S. 385, Mt. Heslington, Nelson (Otamitan Stage). Plate 4 Fig. 1.—Twigs taken from an infected manuka (Leptospermum scoparium) The two piece in the centre have been split to show the thickness of the sooty mould. (× 1.) Fig. 2.—Section through a microsproangium showing the microspores being exuded through the ostiole. (× 500.) Fig. 3.—A crushed perithecium showing an aseus and ascospores. (× 325.) Fig. 4.—A crushed pyenidium with the pyenospores in situ. (× 350.) Plate 6 Fig. 1—Tectarchus diversus female. Fig. 2—Tectarchus diversus male. Fig. 3—Tectarchus ovobessus female. Fig. 4—Tectarchus semilobatus female. Fig. 5—Tectarchus tuberculatus female. Fig. 6—Tectarchus tuberculatus male. Plate 7 Fig. 1—Tectarchus diversus n. sp. female left, male right. Fig. 2—Tectarchus diversus operculum and apex of abdomen viewed from side (an egg is held in the operculum). Fig. 3—Tectarchus ovobessus operculum and apex. of abdomen, viewed from side. Figs 4–7—Female operculum cerci and paraprocts viewed from below: Fig. 4—Tectarchus diversus (egg held in operculum) Fig. 5—Tectarchus orobessus. Fig. 6—Tectarchus semilobatus. Fig. 7—Techarchus tuberculatus. Figs 8–10—Male subgenital plate and apex of abdomen viewed from side. Fig. 8—Tectarchus diversus. Fig. 9—Tectarchus semilobatus. Fig. 10—Tectarchus tuberculatus. Fig. 11—Tectarchus semilobatus, operculum and apex of abdomen viewed from side. Fig. 12—Tectarchus tuberculatus, operculum and apex of abdomen viewed from side with egg held in operculum. Plate 8 Figs. 1–4—Eusternum and sternellum of prothorax and mesothorax. Fig. 1—Tectarchus diverrsus female. Fig. 2— Tectarchus ovobessus female. Fig. 3—Tectarchus semilobatus female. Fig. 4—Tectarchus tuberculalatus female. Figs 5–7—Male subgenital plates viewed from below. Fig. 5—Tectarchus diversus. Fig. 6—Tectarchus semilobatus. Fig. 7— Tectarchus tuberculatus. Plate 9 Fig. 1.—Rhyolite (2280). Large spherulites in a microgranular groundmass Crossed nicols, × 15. Fig. 2.—Keratophyre (2298). Small phenocrysts of albite in a trachytic groundmass. Crossed nicols, × 15. Fig. 3.— Andesite (2249). Amygdules filled with zeolite and quartz. Crossed nicols, × 15. Fig, 4.—Meta-andesite (2272). Andesine phenocrysts partially replaced by analcite (dark.) Crossed nicols, × 15. Fig. 5.— Meta-andesite (2371). Clear secondary albite rims altered original feldspar phenocrysts. Crossed nicols, × 15. Fig. 6.—Meta-andesite (2271). Altered feldspar phenocrysts rimmed with clear secondary albiclase Crossed nicols, × 15. Plate 10 Fig. 1.—Meta-andesite (2240). Albite phenocryst partially replaced by orthoclase. Crossed nicols, × 15. Fig. 2.—Actinolite - quartz - albite - epidote chlorite-schist (2181). Actinolite in radiating acicular prisms. Ordinary light, × 24. Fig. 3.—Quartz-muscovrite-chlorite-epidoteschist (2185). Crossed niclos, × 15. Fig. 4.—Quartz-albite-biotite-garnet-schist. (2189). Small crystals of garnet (black) scattered throughout the rock. Crossed nicols, × 15. Fig. 5—Quartz-andesine-biotite-garnet-schist (2190). Large shattered garnet crystal and a biotite-rich band. Ordinary light, × 24. Fig. 6—Gneissic Granite (2192). Green hornblende partly replaced by biotite (dark). Ordinary light, × 30. Plate 11 Retouched photographs of Permian plant fossils from Gore Subdivision. Fig. 1.—Equisetites sp. × 2. Fig. 2.—Cladophlebis roylei Arber × 3. Figs. 3. 4.—Sphenopteris cf. lobifolia Morris × 3. Fig. 5.—Sphenopteris sp. × 6. Figs. 6, 7.—F. Neuopteridae × 6. Fig. 8.—cf. Linguifolunm × 6. Fig. 9.—Noeggerthropsis hislopu (Bunbury) × 4. Plate 12 Fig. 1—Corticium × 1 Fig. 2—Corticium tellinum × 1 Fig. 3—Corticium scutellare × 2 Plate 13 Photo 1—(Photo ref 1243/36) Ridge podocarp Stands, Rowallan River watershed Western Southland Rmu stands, and kamahi sub-dominant. Occupy the crest of the interfluve. The hill slopes, carry sliver beech/ stands with the latter species steadily increasing in abundance with gain in altitude Mountain beech, indistinguishable from Silver beech in the photo, occur only toward the valley floors (Refer to text p. 341) Plate 14 Photo 2—(Photo ref 1246/37) Coastal fluvro-glacial gravel te podocarp stands Waikoau River Western Southland Heavily stocked ni stands (outlined) occupy the main portion of the gravel tee but silver beech has nvaded the stand around its ente landward and perimeter and down all the streams traversing the Mountain beech occurs on pan sites and mixed mountain beech/silver beech stands occupy the wise slump s when mudstones are exposed (Refer to text p. 351) Plate 15 Photo 3.—(Photo ref 1248/65) sliver beech migration patterns Longwood Range Southland Silver beech pole Stands (dark even ) etend down all Streams draining an isolated ridge Marked) on which an open silver beech/ stand. The forest mass consists of (pa logged) with heavy ta and kamahi No sliver beech are found along any Streams other than those having then source near the ridge crest silver beech stand (Refer to text p. 345). Plate 16 Photo 4.—(Photo ref.: 1244/32). Limestone soils a barrier to migration of mountain beech. Helmet Hill, Western Southland. carries open stands of silver beech and kamahi on the dip slopes and silver beech/rimu/kamahi stands on the escarpment slopes. On siltstones to the east and on mountain beech/silver beech/rimu stands and mountain beech/silver beech/kahikatea stands. Relict matai (single trees) occur to an altitude of 2,000ft. (points marked X). In the extreme south, silver beech has invaded coastal gravel terrace rimu stands. Mountain beech has nowhere crossed the line of limestone outerop save on the driest escarpment slopes to the north. (Refer to text p. 346.) Photo: Crown copyright. Lands and Survery Department. Plate 17 Photo 5.—(Photo ref.: 1238/49). Reliet hill matai/totara/kahikatea stand, Motu Bush, Western Southland. A very open stand of large veteran matai, kahikatea and totara (outlined) forms an encleave within a forest now wholly of silver beech and mountain beech with widely spaced old rimu. No seedling, sapling or pole podocarps occur within the matai stand but there is peripheral eneroachment by the beech speeles. The forest boundary to the south is a typical ‘fire induced’ boundary suspected of being, in part at least, of pre-European origin. Where the forest has recovered after these fires mountain beech is the universal dominant. It is aggressive species over the greater part of the whole forest. (Refer to text p. 355) Photo: Crown copyright. Lands and Survey Department. Plate 18 Photo 6.—(Photo ref.: 1244/60). Overmature matai/kahikatea/rimu stand. Longwood Range. Southland. In this are near Merrivale at the northern end of the Longwood Range the lower slopes (A) carry very open stands of large diameter, defective podocarps which, as evident in the photograph, stand out above a low, dense underwood of scrub hardwood species. Over wide areas there are not more than two or three surviving podocarps per acre. No young podocarps are present. The underwood is floristically very rich. as is usual on old matai sites; 25 separate shrub species have been recorded on a single 1/80th acre quadrat. On the upper slopes of the Range (B) the relict podocarp stand merges into a silver beech stand containing widely spaced large rimu. A few true totara, the only living specimens found in the forests of the Long wood Range, occur at approximately the position marked (T). Refer to text p. 357.) Photo: Crown copyright. Lands and Survey Department. Plate 19 Photo 7.—(Photo ref.: 1477/5). Zonation of stands around open pakihi, Okuru River, South Westland. Forest type distribution patterns such as these are typical of the Westland coastal plains. Around the margins of the pakihgi there are in evidence all stages in the succession from pakihi through manuka scrub to silver pine to rimu high forest. Islands of forest of varying age also occure withing the pakihi on local dry sites. The oldest stands, rimu/rata/kamahi, are found only on well drained sites, e.g., on the hill slopes, on terrace margins. and on well drained recent alluvial soils. Kahikatea and occasional matai occure in association with the rimu on the alluviums and dense kahikatea pole stands form on alluvial soils where these are swampy. In the present instance, also, some silver beech is hound in the stands near the main streams, extensive silver beech forests ovvuring on the mountains a few miles to the east. The stands on the alluviums near the main river have been partly cleared to pasture. Plate 20 Photo 8.—(Photo ref.: 1536/6). Rimu forest of the eoastal plains, Saltwater, Westland. The patehy mottled texture of the stands will be radily apparent. This reflects the strongly group even-aged eondition of the forest and this, in turn, is considered indicative of the origin of the stands—i.e., through progressive eolonisation, by rimu, of pre-existent pakihi. Reliet Silver pine or, more rarely, old stems of manuka, occur within the youngest rimu stands (even-textured light grey pockets). Old rimu occur seattered through heavy stands of rata and kamahi on dry morainie ridges and on other well drained sites along the main streams. (Refer to text p. 380.) Note.—All photographs from an altitude of approximately 12,300ft., within a camera of focal length 8¼ inches to give an approximate photo scale of 4 inches to 1 mile. Reduced to approximately 3 inches to 1 mile on reproduction. Photo: crown copyright. Lands and Survey Department. Plate 21 Fig. 1.—Galaxius breupennis, Fiosty Greek, Westland. Fig. 2.—Galaxius breupennis. Twelve. Mile, Nelson Plate 22 A. Tremellodendropsis transpusio. Fruit body. × 4; B. Tumidapexus ravus Fruit body. × 4. Plate 23 1 S. aviculare pollen mother cell first metaphase n. = 23. New Zealand (Fanal 1) × 2750 2. S. laciniatum p.m c. second metaphase. n. = 46. Australia (S. Oakleigh) × 2750. 3. S. laciniatum p. m c first metaphase n. = 46 New Zealand (Dunedin) × 2750.4 S. aviculare seed and stone-cells from a single fruit New Zealand (Three Kings Is) × 1 5. Ditto S. laciniatum New Zealand (Dunedin) × 1 Plate 24 S. aviculare Forst grown Dunedin from seed ex Fanal I. Auckland Natural size O. U. herb nos 924 925 929 S. laciniatum Ait from Dunedin Natural size O. U. herb no 1616 Plate 25 Fig. 1—Merosis in Blachnum durum (Moore) C. Christen × 1800 η = 28 Fig. 2—Explanatory diagram to interpret fig. 1 Fig. 3—Merosis in Blaechnum culcanicum (Blume) Kuhn, × 1800 η = 34 Fig. 4—Explanatory diagram to interpret fig. 3 Plate 26 Plate 1—Retouched photographs of fossil leaves from the Wanganui Series 1—Piper crenhou cusis nsp Holotype B163/30 × 2 2—Belulites couperi n.sp Holotyupe B163/9 × 2 3—Nothofagus searellae nsp B209/30 × 4 4—Nothotagus searellae nsp Holotype B206/7 × 4 5—Notholagus of Chifor fusea B206/2 × 3 6—Phyllires lamahsis nsp Holotype B209/1 × 3. Plate 27 Fig 3—Aerial photograph of fossil dunes forming South Head Formation at Karpara South Head Exhumed traces of the dunes, are seen in plan on the post-Flandrian Sft terrace which lies in front of the abandoned sea clift running south-west from South Head. The dunes have the general transverse and lobate pattern that is produced at light angles to a formative wind Here, the effective Pleistocene wind direction has been from the south-west—i e., parallel to the present prevailing wind on this coast Recent wind-blown sand, mainly planted with grasses, occupies the lower left portion of the photograph below the white dashed line. The hook at the end of the South Head sandspit appeals in the upper left corner Plate 28 Fig. 1 —Macropathus filifer male lateral view Fig. 2—M. filifer female, lateral view Fig. 3—Macropathus acanthocera female, lateral view Fig. 4 —M. acanthocera male, lateral view Fig. 5 —Macropathus delli male, lateral view. Fig. 6—M. delli female, lateral view Plate 29 Fig. 1 —Macropathus filifer male, dorsal view Fig. 2—Macropathus delli male, dorsal view Fig. 3—Macropathus acanthocera male, dorsal view. Fig. 4.—M. filifer female dorsal view Fig. 5—M. delli female, dorsal view Fig. 6—M. acanthocera female, dorsal view Plate 30 Top Greywacke wall of Karori Cave showing sparse population of Macropathus filifer as compared with those on Stephens Island (below) Bottom Inside concrete water tank on Stephens Island, showing large numbers of Macropathus filifer clustered together on wall and roof with no segregation of adults and nymphs Plate 31 Fig. 1 — Fig. 2 — Plate 32 Fig. 1 —Solifluxion layers (S1 and S2) resting on weathered greywacke bedrock (B), near Belmont; description in text. S1 is spanned by the 3 ft. ruler. Fig. 2.—Neai view of part of Fig. 1. The 3 ft. ruler spans S1 and its base rests on the shaved surface of weathered greywacke bedrock. Note the angularity of the fragments in S1. Fig. 3.—Hand specimen (3in. across) collected from the position marked by the base of the ruler in Fig. 2. Note the sharply defined, smooth, shaved surface of weathered greywacke bedrock on which solifluxion layer S1 rests. (Plate 33. Figs. 1. 2. 3 Photos by M. D. King) Plate 33 Fig. 1—Solifluxion debris resting on a shaved surface of weathered grevwacke bedrock, near Belmont. Note the sharply defined contact (sloping down from left to right just above the hammer). Fig. 2.—Large flakes and fragments of hard, spheroidally weathered grevwacke boulders embedded in solifluxion laver, near Belmont. The ruler (bottom centre) is 3ft. long. Fig. 3.—Solifluxion laver (above the white broken line) thickening downslope. Monagha Avenue, Karoar, Wellington. The base of the 3ft. ruller (centie) rests on a shaved surface of weathered grevwacke bedrock (below the line). Fig. 4.—Angulai solifluxion debris resting on a shaved surface of weathered grevwacke bedrock, Monaghan Avenue Karori. The pencil on the contact is 6in. long. Fig. 5.—A frost-riven flake (below the hammer) from a spherordally weathered grevwacke bonulder embedded in a solifluxion laver, near Belmont. (Plate 3, Figs. 1, 2, 3, 4, 5 Photos by MD King) Plate 34 Fig. 1.—Two solifluxion layers near Wadestown, Wellington. Greywacke basement, weathered red, Overlair by 5 feet of coarse. Pinkish-red solifluxion debris (above 3ft. ruler, and thinning from right to left), overlain by 3 feet of fine, grevish-yellow solifluxion debets. (Photo by M. D. King.) Fig. 2.—Small folds in sandy material at the base of a solifluxion layer when overlies a shaved surface of grevwacke bedrock, near Kaitoke (Photo by M. D. King.) Plate 35 Fig. 1.— Otari peneplain remnant, Wellington. Locality: 3 miles north-north-wet from centre of Wellington city (co-ordinates: N164/315270). Altitude 1,300 feet. View looking north-north-west “Dells” are seen in middle distance at left. (Photo by Victoria University College Department of Geography). Fig. 2.—Detail of Otari surface (Fig. 1). (Photo by C. A. Cotton.) Plate 36 Fig. 1.—View looking south-east across Belmont plateau at summit 1,180 ft. (N160/460365). A massive outcrop of resistant grevwacke reduced to roun-knob form is crowned by an autochthonus block field. The foreground shows, features of fine-textured small relief developed on a belt of deeply weathering greywacke which has apparently undergone progressive denudation below the summit level. (Photo by M. D. King.) Fig. 2.—Branching streamn-cut valley on the Belmont plateau, showing swampv axial strip. Note fine texture of dissection (Photo by M. D. King.) Plate 37 Fig. 1.—Valley head of an interupted cycle hanging above a conspicuous nick (at the interlocking spurs) in the profile of a ravine that dissects the scarp bounding the Belmont plateau on the north-west side (view from divide at head). There are swampy axial strips in the gullies, as in Plate 37, Fig. 2. (Photo by M. D. King.) Fig. 2.—The onque-like valley-head hollow, or dell, shown in Text-fig. 4, as seen from the divide at its head. View looking west. (Photo by M. D. King.) Plate 38 Aerial Photograph of Nugget Point, South Otago. Published by permission of the Department of Lands and Survey. Plate 39 Fig. 1 2—Glycumeris (Grandarinea) chamber Marshall GS 5170, Port Craig Fig. 3—Lima becki Flemming n.sp, holotype Fig. 4—Sectipecten wollastom (Finlay), GS 2944 Bluecliff Fig. 5—Limatula craigensis Fleming n.sp. holotype Figs 6,7—Cuna caerulea Fleming n.sp, holotype, × 14 Figs 8,9—Chama hutoni 68 5170, port craig Fig. 10— aff beata Marwick G8 5170, Port Craig Figs 11 12— Southlandica Fleming n.sp. holotype Plate 40 Fig. 1—Dosi (Kere) aff chathmensis G8 5170 Port Craig Figs 2 3—Marama (Hina) singularis (Marwick), holotype Figs 4–6—Mama(Hina) singularis (Marwick). G8 5170. Port Craig Figs. 7, 8, 12—Astracea n. sp, 7, 12, peripheral spine, 8. operculum, G8 5170. Port Craig Figs 9, 10, 11—Astrae he (Marwick) Recent Figs 13, 14—Ethcea u Fleming n. sp., holotype Fig. 15—Ellicea antorbita Fleming n. sp., holotype Fig. 16—Argo (Haur) woodi Fleming n subgen, n. sp, holotype Fig. 17—Austro coer (Finlay). Fusus corcules (Finlay), G8 2944. Bluecliff. Fig. 21—Alorthoe cf solida Marwick. GS 5170. Port Craig Fig. 22—Penion braze Fleming n. sp. holotype Fig. 23—Lepsiella et maxima Powell and Battium, G8 5170, Port Craig. All figures natural size Plate 41 Fig. 2.—Microfold in chlorite schist, south wall of Copland Vally south of jungle Creek Ptygmate tolds formed from sandstone bands and quartz vens cuttinh across bedding Fig. :3—Microfold in quartz brothe t, west wall of Franz Joset same locates as Fig. 4 Anal plane cleavage (on S2) coincident with bedding surprises on sleeper Plate 42 Fig. 4—Quartz-brotite schist, west wall of Franz Joset Glacier, hall a mile north west of Defrance Hut. Fig. 5.—Crest of microfold in quartz-biotite schist. Thin section from rock shown in Fig. 4. Marked crystallization of biotite along axial-plane cleavages (S2) oblique to relict sedimentary banding (S1) All terms of passage visible between cleavage and true cleavage. Plate 43 Fig. 1—Operculum of A suteri side view to show basal spine. Fig. 2—Operculum of A. prasina side view to show basal tubercle; (abdominal terga numbered in small figures) Fig. 3—Male genitalic segments, A. senta from below, note the two large dark spines (s) on the inner margins of tergum IX Fig. 4—Male genitalic segments, A. senta from side. Fig. 5.—Spines of A. huttoni Fig. 6—Spines of A. geisovii. Fig. 7.—Operculum of A. huttoni, side view to show basal spine Scale A-B for Figs. 1 and 2 = 1 mm Scale C-D for Figs. 3 and 4 = 0.5 mm Scale E-F for Figs. 5 and 6 = 1 cm. Scale G-H for Fig. 7 = 1 mm Plate 44 Fig. 8.—Acanthoxyla fasciata, specimen from Bruce Bay, abdominal segments indicated in small figures Fig. 9.—Acanthoxyla huttoni, Paratype from Karori with right anterior leg lost at final moult and not regenerated Fig. 10–Acanthoxyla prasina, specimen from Wilton's Bush. Fig. 11–Acanthoxyla intermedia Paratype specimen from Karori with two regenerated hind legs. Scale J-K for Figs. 8–11 = 7 cms. Plate 45 Fig. 12—Spines of A suteri Fig. 13.—Spines of A speciosa Fig. 14—Operculum of A intermedia, side view to show basal spine Fig. 15—Operculum of A speciosa, side view to show basal spine.Fig. 16—Operculum of A geisoin, side view to show basal spine Scale K-L for Figs. 12–13 = 1 cm Scale M-N for Figs. 14–16 = 1 mm. Plate 46 Fig. 17—Acanthoxyla speciosa-type specimen Fig. 18–Acanthoxyla inermis-type specimen Fig. 19—Spines of Acanthoxyla senta. Fig. 20—Operculum of A. inermis. side view to show basal tubercle. Fig. 21.—Operculum of A. senta side view to show basal tubercle (T) Scale O-P for Figs. 17–18 = 3 cms Scale R-S for Fig. 19 = 3 cms Scale U-V for Figs. 20–21 = 1 mm. Plate 47