Art. XXIII—On the Dentition of some New Zealand Land and Fresh-water Mollusca, with Descriptions of New Species.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 24, 1891, Page 286

Art. XXIII—On the Dentition of some New Zealand Land and Fresh-water Mollusca, with Descriptions of New Species. By H. Suter. [Read before the Philosophical Institute of Canterbury, 4th November, 1891.] Plates XX.-XXIII. Paryphanta urnula, Pf. From Lowry Bay, Wellington. Plate XX., fig. 1. Radula about 14mm. long, 3 ½mm. broad at the anterior end, tapering posteriorly, with about 40 transverse rows of teeth, the rows forming an obtuse angle of about 120°, salient posteriorly. Teeth, 14—0—14, all aculeate; the first rather small and fragile, rounded anteriorly and pointed behind. The following teeth are growing longer, with a curved ridge across the middle, thus giving them the appearance of an open knife. On the fourth tooth the forming of a median projection on the outer side is beginning, and a longitudinal ridge is running down the posterior half of the tooth. The teeth are increasing in size to the last but one. The thirteenth is long and stout, broadly rounded anteriorly, the head of the tooth soleshaped, a longitudinal almost straight ridge along the inner side of the tooth. Last tooth only about half the length of the foregoing. The radula of this species is remarkable for the small number of teeth, compared with p. busbyi. The specimens were kindly given me by Sir James Hector. Two are kept alive, but will be used later on for further in vestigations. Phacussa hypopolia, Pf. From Hooker Valley, South Island. Plate XX., figs. 2, 3, 4. Jaw strongly arcuated at both ends, rather high, slightly tapering, with numerous narrow plaits, which denticulate

both margins. Considerable magnifying shows the plaits to be imbricate, straight or slightly curved, and vertical. Cutting-margin concave, without median projection. Radula tongue-shaped, consisting of about 110 almost straight transverse rows of teeth, 17—13—1—13—17. Base of central tooth nearly rectangular, somewhat broader at the posterior margin, longer than broad Reflection tricuspid, median cusp almost as broad as the base, with a blunt, short, broad cutting-point, not reaching to the posterior end of the base. Side-cusps very small and short, each with a rudimentary cutting-point. Laterals asymmetrical, with a rectangular oblique base, broadest near the central, and narrower towards the marginals. Reflection tricuspid on the first ten teeth, when the inner cusp obliterates. Median cusp well developed, with a cutting-point which does not reach to the posterior end of the base; broad on the first teeth, narrower and longer on approaching the marginals. Inner side-cusp and cutting-point of the first ten teeth very small. Outer side-cusp first more developed than in the central tooth, but obliterating by degrees. Cutting-point always short. The first marginals are unidentate, with a long narrow rectangular base, beyond which the thorn-shaped cutting-point reaches. All the other marginals are aculeate, stout. They diminish in size considerably towards the margin. The radula of this species does not differ very much from that of Ph. helmsi, Hutt., as described and figured by Professor F. W. Hutton (Trans. N.Z. Inst., vol. xvi., p. 172), but the jaw may be used for distinguishing the species. InPh. helmsi it consists of about 20–25 flat ribs, whilst in Ph. hypoplia there are just about double that number. Amphidoxa corneo-fulva, Pf. From Nerger Range, South Island. Plate XX., figs. 5, a, b, 6, 7. Jaw membranaceous, slightly arcuate, narrower in the middle, ends swollen, blunt; numerous vertical plaits strongly indentate the cutting-margin, but leave the upper margin smooth. Radula long, tongue-shaped, consisting of about 140 straight transverse rows of teeth, 17—16—1—16—17. Central tooth rectangular, much longer than broad, slightly contracted in the middle; reflection large reaching to the middle of the base, unicuspid, with a large cutting-point, not attaining the posterior end of the base. Laterals.—The first ten are very similar to the central, but the reflection is somewhat larger, and the cutting-point stouter and longer, extending a little over the following row of teeth. The following teeth are getting shorter, rhomboidal,

the reflection showing a tendency to become tricuspid; the cutting-point broad, blunt, and short. Marginals stout, first longer than broad, then broader, tridentate, the median tooth the stoutest. In the outer marginals the teeth are blunt, the last marginal minute, with two rudimentary teeth only. For two specimens of this species I am indebted to Mr. B. Bull, of St. Albans. They were collected by Mr. G. J. Roberts in March, 1884, and accompanied by the following note: “From head of Staircase Creek, 5,300ft. above sea-level, on Nerger Range, in slush of snow, hundreds together.” One of the specimens was broken, but fortunately contained the dried animal, which I used for preparing the jaw and radula. I never had a greater surprise in conchological work than when I examined the dentition of this mollusc. The shell is as near that of a Hyalina as it can be, but jaw and dentition are widely different, and they agree with those of our Amphixoda. The shell, of which I give a drawing, corresponds well with Pfeiffer's description, and it differs very much from Hyalina cellaria, with which Professor F. W. Hutton thought it to be identical. The dimensions of the specimen from Nerger Range are: Diameter, greatest 8mm., least 6 ½mm.; height, 3 ½mm.; aperture, height 2 ½mm., breadth 3 ½mm. Amphidoxa compressivoluta, Reeve. From Forty-mile Bush, North Island. Plate XX., figs. 8, 9. Jaw almost straight, membranaceous, with very fine and narrow vertical striæ, one end blunt, the other slightly tapering; a short median projection on the cutting-margin. Considerable magnifying shows the latter to be finely denticulated. Radula tongue-shaped, consisting of about a hundred almost straight transverse rows of teeth, 32—1—32. The number of laterals may be taken at about six, but they are very gradually going over in marginals. Central tooth nearly quadrate, reflection tricuspid, the median cusp with its cutting-point reaching to the posterior end of the base side-cusps sinuated, with a short cutting-point on each. Laterals resembling the central, but the median cusp is stouter, and its cutting-point extends over the posterior end of the base; the inner side-cusp gets broader, its cutting-point more developed, whilst the outer one remains narrowed, and its cutting-point small. In the transition teeth the reflection becomes bicuspid, the inner cusp is large, extending to the posterior end of the base, its strong cutting-point is slightly directed towards the

median line of the radula. To the straight side of the median cusp a sharp, rather stout cutting-point is fastened. The outer cusp hears a short cutting-point. Marginals not much broader than long, the anterior part rhomboidal, the inner ones with three, the outer ones sometimes with four teeth, of which the second on the inner side is the strongest. Last marginals with rudimentary teeth, minute. Amphidoxa chiron, Gray. From Ohaupo, North Island. Plate XX., figs. 10, a, b, 11, 12. Jaw arcuate, membranaceous, vertically plaited with about fifteen rather broad flat plaits, which are separated by narrow grooves. Upper margin smooth, cutting - margin slightly denticulated, and with a blunt median projection. A transverse striation runs from one end to the other. Radula tongue-shaped, consisting of about 110 straight transverse rows of teeth, 12—5—1—5—12. Central tooth rectangular, longer than broad, anterior end curved, reflection rather large, tricuspid; middle cusp long, with the short cutting-point reaching near the posterior end of the base; side-cusps slightly sinuated on the outer sides, cutting-points small. Laterals asymmetrical, rectangular, somewhat larger than the central; reflection large, irregularly shaped, tricuspid, the median cusp in the outer teeth extending to the posterior end of the base, its cutting-point well developed, running partly over the next row of teeth; the inner side cutting-point attaining by degrees a greater development than the outer one, which remains small. The first marginal tooth, together with the last lateral, may be considered as transition teeth; the other marginals broader than long, tridentate, the middle tooth broad, short, the inner one longer and narrower, the outer one short. From the 14th to the 16th tooth the denticles coalesce by degrees into one mass; the last rudimentary. The specimens from Ohaupo, collected by Mr. Charles T. Musson, and of which I give a figure, are so strongly plaited that I first took them for a new species, closely allied to A. chiron; but the dentition is decidedly that of the species mentioned, as described and figured by Professor F. W. Hutton in Trans. N.Z. Inst., vol. xvi. This species seems to vary very much with regard to the plaits. Specimens I collected in the Forty-mile Bush show almost no trace of plaits, but only well-developed growth-lines. The shells from Ohaupo correspond with Gray's description, though I should not call them plaited, but ribbed. A. chiron may be considered as an intermediate form 19

between Amphidoxa s.-str. and the subgenus Calymna, Hutton, which includes the forms with ribbed whorls. Amphidoxa (Calymna) olivacea, n. sp. Plate XXI., figs. 13, a, b, 14, 15. Shell globosely depressed, perforated, shining, pale yellow-olive, without markings, thin and transparent, with very closeset arcuated ribs, which are flatly rounded, about 10 per mm., interrupted on the surface with several distinct spiral grooves. Spire slightly elevated, obtuse; apex smooth. Whorls 3, rather rapidly increasing, rounded, the last slightly flattened on the surface, rounded on the base. Suture deep. Aperture oblique, rotundly ovate, slightly excavated by the penultimate whorl. Peristome very thin, straight, regularly arched, the upper part advancing. Columellar margin not reflected, sharp, vertically slightly arcuated; outer margin strongly arched, the margins approximating. Umbilicus very narrow, not deep; umbilical region infundibuliform, faintly striated. Diameter, greatest 5mm., least 4mm.; height, 3 ½mm.; aperture, height 2mm., breadth 2 ½mm. Hab. Hillyer's Creek, near Auckland (Ch. T. Musson). Scarce. It seems to be rather rare, as amongst the shells collected by Mr. Ch. T. Musson were only three specimens, of which only one is in good condition. This one was used for description, but I do not think it to be quite adult. Fortunately it contained the dried animal, which I used for preparing jaw and radula. Jaw arcuate, rather solid, upper margin straight in the middle; consisting of numerous vertical plaits, which indent the upper margin. Ends tapering. On the median part of the cutting-edge a well-pronounced projection. The plaits are laid close together, not imbricating. Radula tongue-shaped, consisting of about 100 almost straight transverse rows of teeth, 17—8—1—8—17. Central rectangular, longer than broad, slightly broader posteriorly; reflection tricuspid, median cusp long, slender, with a short cutting-point reaching to the posterior end of the base. Side-cusps short, rounded, each with a minute cutting-point. Laterals symmetrical, the same as the central, but the base slightly rhomboidal, the median cusp somewhat longer, and its cutting-point lying on the following row of teeth. The last two are in transition to marginals. Marginals.—The first three with a quadrate base, reflection bicuspid, the inner cusp broad, reaching to the posterior end of the base, and its stout cutting-point over the following row

of teeth. The other marginals get much broader than long, and are provided with three or four denticles, which in the last teeth are more or less coalescing, with the denticles blunt. Therasia decidua, Pf. From Hooker Valley, South Island. Plate XXI., figs. 16, 17. Jaw membranaceous, horseshoe-shaped, with imbricating plaits, which are very broad in the centre, narrower towards the ends; they nearly reach to the upper margin, but are rather distant from the cutting-margin, which has a pronounced median projection. Radula long, tongue-shaped, consisting of about 150 transverse almost straight rows of teeth, 29—8—1—8—29. Central tooth rectangular, long and narrow. Reflection small, side-cusps hardly visible, with one median cutting-point only, reaching nearly to the posterior margin of the base. Laterals with a broader base, reflection larger, the inner teeth with one cutting-point only, three on the outer ones. The median cutting-point stout, long, extending almost to the posterior margin, the side cutting-points small. Marginals first bicuspid, then tricuspid, rounded at the anterior margin. On the outer marginals the cutting-points coalesce in one, which is trifid. The last two or three are bidentate. Psyra tullia, Gray. From Sealey Range, South Island. Plate XXI., figs. 18, 19. Jaw slightly arcuate, not tapering, with about 14 flat broad plaits slightly indenting both margins. Radula consisting of about 80 transverse straight rows of teeth, 15—6—1—6—15. Central tooth rectangular, somewhat longer than broad. Reflection tricuspid, median cusp slender and reaching with its short cutting-point over three-quarters of the length of the base. Side-cusps rounded, short, each with a minute cutting-point. Laterals highly asymmetrical, base rectangular, much longer than broad. Reflection bicuspid, the internal cusp bearing a strong cutting-point, reaching to the posterior margin of the base; the external cusp rather broad, with a short cutting-point. Marginals.—The first two tridentate, resembling somewhat the last laterals, the internal cutting-point being the longest, the anterior portion nearly quadrate. The following teeth get gradually broader, and of the three well-developed cutting-points the median is the longest. The last marginals are small, bidentate.

The radula of this species differs considerably from those known of the other species of the genus. Patula bianca, Hutt. From Forty-mile Bush, North Island. Plate XXI., figs. 20, 21. Jaw membranaceous, slightly arcuated, not tapering, faintly vertically striated, with a slight median projection on its cutting-margin. Radula tongue-shaped, central part of the straight transverse rows somewhat advanced. Teeth, 7—4—1—4—7. Central tooth rectangular, longer than broad, reflection tricuspid, the middle cusp nearly reaching to the middle of the base, with a short cutting-point; side-cusps small, rounded, with a rudimentary cutting-point on each. Laterals.—All four very much like the central, but somewhat broader and shorter; the median cusp nearly reaching to the posterior end of the base, and its well-developed cutting-point beyond it. Marginals from quadrate to much broader than long, tridentate, cutting-points stout; the tenth tooth with four cutting-points, of which the two outer. ones are very small. Last marginal small, bidentate. The jaw and radula differ somewhat from the var.montana, as will be seen by comparing it with the figures given in Trans. N.Z. Inst., vol. xxiii., pl. xvii., figs. k, L. Patula anguicula, Reeve. From Forty-mile Bush, North Island. Plate XXI., figs. 22, 23. Jaw membranaceous, arcuate, not tapering, with a few vertical and one transverse striæ. Radula tongue-shaped, formed of about 100 straight transverse rows of teeth, 7—4—1—4—7. Central tooth very little longer than broad, rectangular, with a tricuspid reflection, of which the median cusp with its short cutting-point reaches to the end of the base. The sidecusps are short, rounded, one minute cutting-point on each. Laterals quadrate, broader than the central, reflection tricuspid, middle cusp reaching to the posterior margin of the base and its short cutting-point beyond it. Side-cusps sinuated, with a short cutting-point each. Marginals from quadrate to much broader than long, tridentate, the median tooth being the largest. Last marginal minute, bidentate. The description and figures are from a specimen which is undoubtedly P. anguicula, whilst that described and figured in Trans. N.Z. Inst., vol. xvi., was to my knowledge a young form of P. buccinella. The difference between both, however, is not considerable.

Patula sylvia, Hutt. From Forty-mile Bush, North Island. Plate XXI., figs. 24, 25. Jaw thin and fragile, slightly arcuate, not tapering, with strong distant vertical striæ. Both margins smooth. A faint indication of a median projection on the cutting-margin. Radula tongue-shaped, consisting of about 80 slightly curved transverse rows of teeth, 9—5—1—5—9. Central tooth rectangular, longer than broad, tricuspid, median cusp long, its very short cutting-point extending to the posterior end of the base. Side-cusps sinuated, with a short cutting-point on each. Laterals.—The first three show no difference from the central, the fourth is more slender, the median cusp with a longer cutting-point, extending very little over the next row of teeth. The cutting-point on the inner side-cusp stouter. The fifth lateral is slightly rhomboidal, the median cusp shorter, but its cutting-point longer and stouter, the inner cutting-point still more developed. Marginals.—The first ones almost quadrate, the outer ones broader than long. Three to four cutting-points, of which the second on the inner side is the longest. Last marginals small, unidentate. Patula colensoi, Sut. From Forty-mile Bush, North Island. Plate XXI., figs. 26, 27. Jaw arcuate, very thin and fragile, not tapering, with a faint median projection on the cutting-margin; distantly and faintly striated. Radula tongue-shaped, covered with about 90 transverse rows of teeth, straight in the middle, slightly bent forwards towards the margins. Teeth, 13—4—1—4—13. Central tooth large, almost quadrate, sinuated at the anterior end; reflection tricuspid, median cusp as long as the base, and its short cutting-point reaching beyond it; sidecusps extending over one-third of the base, a small cutting-point on each. Laterals shorter than the central, quadrate, reflection much the same as in the central, tricuspid, the median cusp a little shorter. Marginals tridentate, the head of the first ones irregularly shaped, the others much broader than long, with long slightlycurved teeth, of which the external one is short. Last marginal small, unidentate. Patula varicosa, Pf. (=P. timandra, Hutt.). From Riccarton Bush, South Island. Plate XXII., figs. 28, 29. Jaw membranaceous, very fragile, slightly arcuate, with faint and distant vertical striæ. Both margins smooth.

Radula tongue-shaped, consisting of about 70 transverse rows of teeth, straight in the middle, slightly bent forwards on both sides. Teeth, 10—5—1—5—10. Central tooth asymmetrical, rectangular, not much longer than broad; reflection tricuspid, the central cusp narrow, reaching very little beyond the middle of the base; on its left side a stout transverse cutting-point, directed towards the left posterior corner of the base, a very small cutting-point on the right side of the cusp. The left side-cusp sinuated, with a rather long vertical cutting-point; right side-cusp rounded, with a stout and long vertical cutting-point. Laterals.—The first four on each side of the central very similar to it, but quadrate, the reflection larger. The median cusp reaches almost to the end of the base; on its left side is a spur-like, transverse, broad and sharp cutting-point reaching beyond the base, on the right side a much smaller one. The side-cusps, which are sinuated, have a rather long vertical cutting-point on each, which is more developed on the right cusp. In all other radulæ I have seen the teeth on the right side of the central are the inversion of those on the left side, which is not the case here. All the four laterals, on the left and right side of the central, show the very same arrangement of the cusps and cutting-points, thus rendering the median part of the radula asymmetrical, as the figure indicates it. The fifth lateral somewhat longer than broad, tricuspid, the cusps all with one strong vertical cutting-point. Marginals broader than long, tridentate, the fourteenth sometimes with four denticles. First not very broad; the others get much broader and shorter towards the margin. Last marginal small, with two denticles. The central tooth and the four laterals on each side of it are so widely different from all those known to me in other species that I do not know whether this radula must be considered as abnormal or not. Unfortunately, I have no animal of the same species at my disposal just now, and therefore am unable to decide the question. Should further investigation prove it to be normal for the species, the creation of a new genus would no doubt be justified. Patula Jessica, Hutt., is in its shell closely allied to P. varicosa, and an examination of its dentition, which is not known yet, would be highly interesting, as it might show similar peculiarities. Patula sterkiana, Sut., var. reeftonensis, n. var. This variety differs from the species described in last volume of the Transactions, p. 85, by its considerably-smaller size and the much more distant ribs, of which there are only about 15 per mm. Besides this there is no difference.

The jaw and radula are very much the same as in the species. Dentition, 12—4—1—4—12. The teeth of the first marginals are less oblique. Diameter, greatest 2 ¾mm., least 2 ¼mm.; height, 1 ¾mm. Hab. Boatman's, near Reefton, from whence it was sent to me by Mr. A. T. Cavell. At first sight this shell seems to be an intermediate form betwen P. sterkiana and P. brouni, but a close examination shows it to be much more allied to the first, though the ribs are much coarser and more distant. The radula fully justifies its estimation as a variety only of P. sterkiana. Patula sterkiana, Sut., forma major. This shell corresponds in every respect with the species from Hooker Valley, but is somewhat larger, no doubt owing to the difference in the habitat. Diameter, greatest 4 ½mm., least 4mm.; height, 2 ½mm Hab. Owaka (Clutha), where it was found by Mr. J. T. Bryant. As was to be anticipated, the new species I found in the Hooker Valley are very likely distributed over many other parts of this Island, and this has been confirmed now, at least, for one of them. Patula biconcava, Pf. From Forty-mile Bush, North Island. Plate XXII., figs. 30, 31. Jaw slightly arcuated, membranaceous, not tapering, with one transverse and several vertical fine striæ. Radula tongue-shaped, consisting of about 120 almost straight transverse rows of teeth, 14—5—1—5—14. Central tooth nearly quadrate, large, with a tricuspid reflection, of which the median cusp reaches to the end of the base, the short cutting-point beyond it. Side-cusps oval, with one minute cutting-point on each. Laterals very much the same as the central; in the first two the median cutting-point is a little longer. First marginals with an irregular head, getting broad and short in the external teeth, tridentate, the median tooth strongest developed, most of the teeth slightly curved. The presence of a jaw, as well as the form of the teeth, show clearly that Pfeiffer and I were greatly mistaken in placing this mollusc, according to the form of the shell, in the genus Diplomphalus. Patula subantialba, Sut. (= Diplomphalus subantialba, S.). From Forty-mile Bush, North Island. Plate XXII., figs. 32, 33. Jaw strongly arcuate, membranaceous, ends rounded, both margins smooth, faintly and distantly vertically striated.

Radula long and narrow, consisting of about 100 straight transverse rows of teeth, 7—4—1—4—7. Central tooth rectangular, considerably longer than broad, reflection tricuspid, median cusp slender, half the length of the base, with a short blunt cutting-point; side-cusps small, rounded, each with one rudimentary cutting-point. The first two laterals with the base like the central, tricuspid, median cusp long and slender, reaching with its very short cutting-point to the posterior end of the base; side-cusps sinuated, one very short cutting-point on each. In the third and fourth the reflection is larger, the median cusp shorter, its cutting-point longer and passing a little over the next row of teeth; the inner side-cusp obliterates, and there is a rather long cutting-point; the outer side-cusp is rounded, and supports a minute cutting-point only. Marginals.—The first two with the reflected margin as broad as long, in shape like the last lateral; median cutting-point stout and rather long, the side cutting-points as in the last lateral. The following marginals get much broader than long, tridentate, the last two without visible denticulation. Thera stipulata, Reeve. From Owaka (Clutha), South Island. Plate XXII., figs. 34, 35. The dentition of this mollusc has already been described by Professor F. W. Hutton in Trans. N.Z. Inst., vol. xvi. The dentition of several specimens which I examined showed a great variability in the number of laterals, and especially in the form of the last marginals. Professor Hutton gives the number of teeth 12—1—12, of which three or four are laterals. In one specimen I found the dentition to be 10—4—1—4—10, and this one is figured. The twelfth tooth has four denticles, and the last three. In another specimen the dentition was 10—6—1—6—10, the last two marginals, which are figured, differing considerably from those on the other radula. Thera barbatula, Reeve (=H. beta, Pf.). From Dunedin. Plate XXII., figs. 36, 37. Jaw almost straight, convex on the upper margin, straight on the cutting-margin, but with a faint indication of a median projection; very thin, fragile, and transparent; broadly and faintly vertically striated, the cutting-margin slightly and broadly denticulated. Sometimes a transverse line crosses the vertical striæ in the middle. Radula tongue-shaped, formed by about 100 almost straight transverse rows of teeth, 15—1—15, of which six or seven may be taken as laterals. Central tooth rectangular, longer than broad, reflection tricuspid, median cusp reaching to the middle of the base, and

its cutting-point to the posterior end of it. Side-cusps rounded, with one small cutting-point on each. Laterals like the central, but slightly asymmetrical, more so on approaching the marginals, base slightly broader; reflection tricuspid, the median cusp somewhat longer than in the central, its cutting-point reaching over the following row of teeth; side-cusps sinuated, the inner with a rather strong cutting-point, the outer with a very small one only. Marginals much broader than long, first tridentate, in the twelfth to the fourteenth there are usually four denticles on each; the last has a very narrow base, with a minute denticle. Phrixgnathus glabriuscula, Pf. From Mount Wellington, near Auckland. Plate XXII., figs. 38, 39. Jaw arcuate, consisting of about 20 broad slightly imbricating plaits, which are papillate. Both margins denticulated, the denticles of the cutting-margin fringed by the papillæ. Radula.—Transverse rows of teeth curved, with the rows of marginals directed forwards. Teeth, 26—1—26, of which about 14 are laterals. Central tooth rectangular, long and very narrow; reflection unicuspid, with a short cutting-point, both together extending over the anterior third of the base only. Laterals rectangular, little longer than broad, bicuspid, the inner cusp with a long oblique cutting-point, reaching to the posterior margin of the base; the outer cusp with a short cutting-point. Marginals quadrate, bicuspid, with two short cutting-points. Phrixgnathus transitans, n. sp. Plate XXII., fig. 40, a, b. Shell conoidal, subperforated, finely striated with growthlines, faintly shining; colour pale yellow-horn, irregularly banded with chestnut; transparent, fragile. Spire conoidal, apex rather obtuse. Whorls 5, slowly and regularly increasing, rather flattened, the last acutely keeled, striæ very delicate, slightly arcuate; suture not deep, not margined. Aperture vertical, subrhomboidal; peristome rather thin, angulated; outer lip strongly callous, the white callosity reaching to a good distance in the interior. Columellar margin slightly deflexed, callous, short, regularly arched. Base convex. Umbilicus very narrow, partly covered. In young specimens the callosity extends very far backwards, and the umbilicus is open. Diameter, greatest 3mm., least 2 ½mm.; height, 2 ½mm. Hab. Heavy bush, Parua Bay, Whangarei (Ch. T. Musson). Evidently scarce. This species is very near Ph. marina, Hutt., but has no lamellæ or teeth in the aperture, and the suture is not margined.

It may be considered as an intermediate form between Phrixgnathus and the subgenus Laoma. Amongst the few specimens none had the animal left in it, and the dentition therefore remains unknown for the present. Phrixgnathus (Laoma) marina, Hutt., from Forty - mile Bush, North Island. Plate XXIII., figs. 41, 42. Jaw arcuate, with about 24 broad vertical plaits, which are strongly papillate, as is typical of the genus. Both margins are denticulated, the cutting-margin fringed by papillæ. Radula tongue-shaped, formed by about 110 straight transverse rows of teeth, 30—1—30. Central tooth rectangular, nearly three times as long as broad, reflection very short, rounded, with one short cutting-point only, the whole covering one-third of the base. No laterals to be distinguished. Marginals rectangular, a little longer than broad, reflection bicuspid, the inner cutting-point long, the outer short; last marginals small, broader than long, with two equally-developed short denticles. The radula of Ph. nerissa, Hutt., is just the very same. Maoriana pseudoleioda, Sut. From Forty-mile Bush, North Island. Plate XXIII., figs. 43, 44. Jaw membranaceous, arcuate, slightly tapering, with faint vertical and one transverse striæ. Radula tongue-shaped, consisting of about 90 nearly straight transverse rows of teeth, 11—4—1—4—11. Central tooth rectangular, little longer than broad, reflection tricuspid, median cusp slender, reaching with its rather short cutting-point to the posterior end of the base; side-cusps small, rounded, no cutting-points seen. Laterals broader than the central, but very much the same; all the cusps stouter; in the third and fourth the median cusp and cutting-point are slightly bent inwards. Marginals much broader than long, with three to four denticles, of which the second innermost is the stoutest; last marginal small, with one denticle only. Maoriana wairarapa, Sut. From Forty-mile Bush, North Island. Plate XXIII., fig. 45. Jaw not seen. Radula very minute, long and narrow, consisting of about 100 slightly-curved transverse rows of teeth, 6—4—1—4—6. Central tooth rectangular, longer than broad, reflection tricuspid, median cusp not much longer than the side-cusps, its

large cutting-point nearly reaching to the posterior end of the base. Side-cusps with very small cutting-points, one on each. Laterals much like the central, but a little narrower, and the median cutting-point reaching beyond the margin of the base. Marginals broader than long, the fifth and sixth with a well-developed median projection and denticle; tridentate, the last very broad and short; all the denticles coalesced in a slightly-denticulated mass. Maoriana hectori, Sut. From Forty-mile Bush, North Island. Plate XXIII., figs. 46, 47. Jaw membranaceous, slightly arcuate, ends blunt, with a few distant striæ starting from its upper margin. Radula tongue-shaped, consisting of about 100 slightly undulating transverse rows of teeth, 10—6—1—6—10. Central tooth nearly quadrate, reflection tricuspid, median cusp long, reaching with its short cutting-point to the posterior end of the base. Side-cusps rounded, with a rudimentary cutting-point on each. Laterals very much the same as the central, but somewhat smaller. Marginals broader than long; the first one tridentate, the following quadridentate, and the last small and bidentate. The second tooth is best developed. Maoriana microundulata, Sut. From Forty - mile Bush, North Island. Plate XXIII., figs. 49, 50. Jaw membranaceous, ends blunt, distantly vertically striated, and the upper margin rather strongly denticulated. Radula tongue-shaped, with slightly undulating transverse rows of teeth, 10—4—1—4—10. Teeth larger than in any other species of the genus. Central tooth large, rectangular, not much longer than broad, anterior end of the base sinuated, reflection tricuspid; middle cusp narrow, reaching with its short cutting-point to the posterior end of the base; side-cusps rather large, pointed on the anterior and rounded on the posterior end, each with a broad, short, blunt cutting-point. Laterals almost like the central, but diminishing considerably in size towards the marginals; the fourth lateral with the inner side-cusp and cutting-point longer. Marginals broader than long, with rather strong denticles; the last small, with four denticles. The radula of this species is distinguished by the relative considerable size of the central and first lateral teeth.

Maoriana aorangi, Sut. From Hooker Valley, South Island. Plate XXIII., figs. 51, 52. Jaw arcuate, narrow, slightly tapering, with about ten distant vertical striæ. Radula tongue-shaped, membranaceous, consisting of about 90 straight transverse rows of teeth, 10—7—1—7—10. Central tooth rectangular, somewhat longer than broad, reflection tricuspid; middle cusp narrow, reaching with its short cutting-point to the posterior end of the base; sidecusps short, rounded, cutting-points rudimentary. Laterals much the same as the central, but the median cusp reaching a little beyond the base. Marginals broader than long, tridentate, the median tooth the longest, the sixteenth very broad and short, bidentate, and the last minute, quadrate, with a rudimentary denticle. Pupa neozelanica, Pf. From Forty-mile Bush, North Island. Plate XXIII., figs. 53, 54. Jaw arcuate, ends blunt, with distant vertical striæ; upper margin slightly denticulated, a blunt median projection on the cutting-edge. Radula tongue-shaped, consisting of about 90 straight transverse rows of teeth, 11—5—1—5—11. Central almost quadrate, indented at its anterior end; reflection tricuspid, the middle cusp and its short cutting-point reaching within a short distance from the posterior end of the base; side-cusps with a small cutting-point each. Laterals somewhat larger than the central, but, otherwise, very much like it; median cutting-point extending a little over the next row of teeth. Marginals broader than long; sixth to twelfth tooth tridentate, the middle tooth being the largest; the thirteenth to fifteenth with four denticles, of which the second is somewhat longer; last marginal broad and narrow, with one blunt cutting-point. The radula of our Pupa differs considerably from all the others of the genus I have seen. Limnæa alfredi, Sut. From Hooker Valley, South Island. Plate XXIII., figs. 55, 56. Jaw consisting of three pieces, as is well known for the genus. Radula tongue-shaped, consisting of about 90 straight transverse rows of teeth, 16—5—1—5—16. Central rectangular, twice as long as broad, narrower anteriorly, reflection minute, bicuspid. Laterals almost quadrangular, slightly sinuated anteriorly, reflection about one-third of the length, broad, with two long

cutting-points, reaching near the posterior end of the base. In the outer laterals the inner cutting-point attains a greater length. Marginals tridentate, first broad with strong denticles, then gradually getting longer and narrower, with the denticulations on the outer side. Last marginal minute, unidentate. Realia egea, Gray. From Forty-mile Bush, North Island. Plate XXIII., fig. 57. Radula long, ribbon-like, consisting of about 100 transverse rows of teeth, 3—1—3. The laterals are fixed in an oblique line running backwards under an angle of 45° to the rhachidian line. Central tooth as long as broad, constricted in the middle; anterior part very broad, oval, with seven denticles, of which the median bears a broad blunt cutting-point; posterior part much smaller, about one-half the breadth of the anterior, with one denticle in the middle. First lateral broad and oval anteriorly, with a short stalk and five denticles. Second lateral much like the first, but broader posteriorly, and the sides more straight; with four denticles, of which the two innermost are sometimes united in one. Third lateral club-shaped, with two deep notches on the inner side, thus rendering it tridentate. Two minute denticles may be observed on the anterior rounded end. A ridge runs down on the interior side. Hydrocena purchasi, Pf. From Forty-mile Bush, North Island. Plate XXIII., figs. 58, H.P., H.C. Radula ribbon-like, consisting of very numerous transverse rows of teeth, ∞. 1. (1 + 1 + 1). 1. ∞. The side-teeth running backwards at a sharp angle to the median line. Central teeth three, hyaline, very difficult to be seen; they are difficult to be seen; they are distant from one another, long and narrow, with one ref-lection on each. Laterals long and narrow, with a short tooth-like projection on the middle of the inner side. Marginals rectangular, much longer than broad, with a denticulated reflection on the anterior side. They are very numerous, and diminish gradually in size towards the margin. This is the typical radula of the genus Hydrocena, and there is now no doubt possible about the generic position of our minute mollusc. Moreover, for comparison, I give drawings of the operculi of H. cattaroënsis (H.C.) and H. purchasi (H.P.), showing their apophysis and striations.

Explanation of Plates XX.-XXIII. Plate XX. Fig. 1.Paryphanta urnula, Pf., teeth, X 60. Fig. 2.Phacussa hypopolia, Pf., jaw. Fig. 3." " " part of jaw, X 240. Fig. 4." " " teeth, X 480. Fig. 5.a, b.Amphidoxa corneo-fulva, Pf. Fig. 6." " "jaw. Fig. 7." " " teeth, X 480. Fig. 8." compressivoluta, Reeve, jaw. Fig. 9." " " teeth, X 480. Fig. 10.a, b." chiron, Gray. Fig. 11." " " jaw. Fig. 12." " " teeth, X 480. Plate XXI. Fig. 13.a, b.Amphidoxa olivacea, n. sp. Fig. 14." " "jaw. Fig. 15." " " teeth, X 480. Fig. 16.Therasia decidua, Pf., jaw. Fig. 17." " " teeth, X 480. Fig. 18.Psyra tullia, Gray, jaw. Fig. 19." " " teeth, X 480. Fig. 20.Patula bianca, Hutt, jaw. Fig. 21." " " teeth, X 720. Fig. 22." anguicula, Reeve, jaw. Fig. 23." " " teeth, X 480. Fig. 24." sylvia, Hutt., jaw. Fig. 25." " " teeth, X 480. Fig. 26." colensoi, Sut., jaw. Fig. 27." " " teeth, X 480. Plate XXII. Fig. 28. Patula varicosa, Pf., jaw. Fig. 29. " " " teeth, X 720. Fig. 30. " biconcava, Pf., jaw. Fig. 31. " " " teeth, X 480. Fig. 32. " subantialba, Sut., jaw. Fig. 33. " " " teeth, X 720. Fig. 34. Thera stipulata, Reeve, jaw. Fig. 35. " " " teeth, X 480. Fig. 36. " barbatula, Reeve, jaw. Fig. 37. " " " teeth, X 480. Fig. 38. Phrixgnathus glabriuscula, Pf., jaw, X 240. Fig. 39. " " " teeth, X 720. Fig. 40. a, b." transitans, n. sp. Plate XXIII. Fig. 41. Phrixgnathus marina, Hutt., part of jaw, X 240. Fig. 42. " " " teeth, X 720. Fig. 43. Maoriana pseudoleioda, Sut., jaw. Fig. 44. " " " teeth, X 720. Fig. 45. " wairarapa, Sut., teeth, X 720. Fig. 46. " hectori, Sut., jaw. Fig. 47. " " " teeth, X 720. Fig. 49. " microundulata, Sut., jaw. Fig. 50. " " " teeth, X 720.

Fig. 51. Maoriana aorangi, Sut., jaw. Fig. 52. " " " teeth, X 720. Fig. 53. Pupa neozelanica, Pf., jaw. Fig. 54. " " " teeth, X 720. Fig. 55. Limnæa alfredi, Sut., jaw. Fig. 56. " " " teeth, X 480. Fig. 57. Realia egea, Gray, teeth, X 480. Fig. 58. Hydrocena purchasi, Pf., teeth, X 720. Fig. H.P. " " " operculum. Fig. H.C. " cattaroënsis, Pf.,operculum.