Art. XXI.—Notes on some Branchiate Mollusca.
[Read before the Philosophical Institute of Canterbury, 7th July, 1881.]
Octopus Maorum. Dentition. The central tooth varies much in shape; usually it has only a median cusp, which carries a long cutting point at its end, and a small one on each side, but sometimes there is a small cusp behind each smaller eutting point. The first lateral is rudimentary, with a small curved cusp. The second lateral is short and broad, its breadth being four or five times its length, and is more or less curved; it has a short triangular cutting point at each end, the outer one of which is hidden by the base of the third lateral. The third lateral has a quadrate base, and a long curved cutting point, blunt at the end. The marginal plate is large, its breadth more than twice its length; it tapers outwards; the anterior margin is slightly concave, the posterior is convex. (Pl. VI., fig. A.)
The drawing is taken from a very small specimen obtained at Wellington.
Ommastrephes sloanii. Dentition. The central tooth is tricuspid, the median cusp rounded, the side cusps sharply pointed; the median cusp carries a long narrow cutting point. The first lateral is bicuspid; the outer cusp is sharp and without a cutting point, the inner cusp is rounded, and with a narrow sharp cutting point slanting slightly inward. The second lateral has a quadrate base, and a single cusp bearing a long sharp curved cutting point. The third lateral is like the second, but has an aculeate base. The marginal plate is small and oval. (Pl. VI., fig. B.)
The drawing is from a very small specimen obtained at Dunedin.
Euthria lineata. Dentition. The central tooth is nearly twice as broad as long, with three sharp denticles on the upper anterior surface. The laterals have a long curved denticle on the outside and two small ones close together on the inside. They lie close to the central tooth. (Pl. VI., fig. D.) The nucleus of the operculum is apical, forming the apex. The drawing was made from a specimen an inch in length, intermediate between varieties A. and C. It was obtained at Sumner.
Cominella funerea. Animal yellowish white. The eyes are half way up the tentacles, which are marked with black in the region of the eyes. Top and sides of the head with dead-white spots. Siphon long and recurved, white speckled with black. Foot slightly expanded and emarginate in front, rounded behind; with two black spots in front.
Operculum with the nucleus apical, within the apex, the margins simple.
Dentition. The central tooth is curved, rather swollen at each end, its breadth four times its length; it has three equal denticles in the middle on its anterior surface. The lateral teeth have two denticles, the outer being the longer, and more curved; they lie distant from the central tooth. (Pl. VI., fig. c.)
The specimen from which the drawing was made was obtained at Sumner.
Columbella Choava. Animal yellowish white, with a narrow black longitudinal line on the back of the head, between the eyes; some scattered dead-white spots on the body and siphon. Tentacles thick, not tapered, approximated; the eyes at their outer bases. Siphon curved. Foot expanded in front, and notched at each side. No operculum. (Pl. VII., fig. o.)
Dentition. 1–0–1; the central portion of the radula is thickened, and divided transversely into membraneous plates, which are broader than long, but the plates bear no teeth. The lateral teeth are versatile; they are curved, pointed at the end, and with two small denticles on the concave side. (Pl. VII., fig. P.)
This species occurs occasionally on seaweed in Lyttelton Harbour. I described the animal in the “Transactions of the New Zealand Institute,” vol. xiii., p. 201, by mistake, under the name of Defranehia luteo-fasciata.
Struthiolaria papulosa. The dentition is remarkably like that of Trochita. The radula is delicate and short, with only about 24 transverse rows of teeth. The central tooth has a quadrate base; the reflected portion is triangular, rather longer than broad, and denticulated on each side. The first lateral has a breadth of nearly twice its length, and the short reflected portion is slightly denticulated on the margin. The second and third laterals are nearly similar, but the base of the second is rather broader and squarer than that of the third; they are versatile. Both are long and curved, the apex blunt and slightly bent over; both are denticulated at the end and on either side near the apex, the denticulations stronger on the outer side. (Pl. VI., fig. H.)
In the male the denticulations are stronger than in the female, in all other respects they are alike. The drawing is taken from a specimen collected at Nelson by Mr. J. D. Enys, in it the teeth are separated to show their form. In their proper position the apices of the second and third laterals nearly meet in the centre. The breadth of the radula is .019 inch, and its length about .07 inch, in a full-sized specimen.
Trochita novæ-zealandiæ. Dentition. The radula has about 44 transverse rows of teeth; the second and third laterals are versatile. The central tooth has a broad rounded base, the reflected has a median cusp with four small denticles on each side; the cusp has a sharp cutting point.
The first lateral is somewhat triangular in shape, its breadth being three times its height; the reflected portion is denticulated on the margin, and there is a large cutting point at the inner end, with a small one inside it. The second and third laterals are nearly similar, the apices are blunt and denticulated; the outer margin is denticulated in both, while the third lateral has also some denticulations on the inner margin. (Pl. VII., fig. A.)
Littorina cincta. Animal. Foot sooty brown; head brownish black, with a white space round the eye; tentacles brownish black with white tips, and a white triangular mark at the base.
Dentition. Radula very long; .01 inch in breadth. Central tooth .002 inch in length, with a rounded cutting point. The first lateral has two large cutting points; the second lateral has four, and the third lateral five cutting points. The length of the third lateral is .004 inch. (Pl. VII., fig. D.) The drawings were made from a specimen from Sumner, the axis of which was .43 inch. The operculum is sub-spiral, the nucleus near the end.
This species varies very much in colour.
Littorina cærulescens. Animal and operculum as in L. cincta. The dentition is smaller than in L. cincta, and the cutting points finer. In a specimen with an axis of .42 inch, the length of the central tooth was .015 inch, and that of the third lateral .025 inch. Breadth of radula, .006 inch. (Pl. VII., fig. E.) According to Mr. Gwyn Jeffreys, this species is identical with L. neritoides, Lin.
Fossarina varius. Animal. Foot white, simple and truncated in front; head dark purple black, with a reddish tinge on each side of the neck; rostrum short, tipped with yellow; tentacles moderate with the eyes at their outer bases, white irregularly ringed with black. Dentition. This much resembles that of Littorina, but the third lateral tooth is not broad at the apex, and the radula is short. (Pl. VII., fig. B.) The radula is .005 in breadth. The operculum is subspiral, with the nucleus central. (Pl. VII., fig. c.)
This species is common at Sumner, associated with L. cincta and L. cærulescens, on the rocks, above low-water mark.
Janthina communis. The radula has numerous aculeate teeth, which decrease in size towards the anterior end; they do not seem to be arranged in transverse rows. The teeth have a simple hooked apex, and a slightly expanded emarginate base. The length of a posterior tooth is .03 inch, that of an anterior tooth is .008 inch. (Pl. VII., fig. F.)
The specimen was given me by the Hon. G. McLean, who captured it in a towing net off the coast of the North Island.
Turbo smaragdus. Dentition. The cusps of the teeth are smooth, with cutting points. The central tooth and the laterals have one cutting point each; the marginals have two each, the inner being the larger; in the first three or four marginals these points are very large and acute, in the other marginals they are rounded. (Pl. VII., fig. G.)
Zizyphinus punctulatus. Dentition. All the teeth have denticulated apices without cutting points. The first two or three marginal teeth are denticulated on the outside only; the rest, as well as the central tooth and the five laterals, on both sides. (P. VII., fig. H.)
Anthora tiarata. Dentition. The central tooth is broader than long, the cutting point, with five strong denticles on each side, at the base. The cutting points of the laterals have four or five denticles on the outside, the inside is smooth; the cutting points increase in length outward. All the marginal teeth are small, being well marked off from the laterals; the cutting points are small and denticulated on the outside. (Pl. VII., fig. N.)
Canthaidus texturatus. Animal. Foot white along the sides, marbled with dark purple, which colour forms a transverse band on each side of the operculum; the hinder part is light reddish brown margined with white. Head purplish red, with a pale line down the middle. Tentacles long, white, fringed. Eye peduncles reddish. Filaments, three on each side, white. Side lappets white.
Dentition as usual, the central tooth longer than broad. (Pl. VII., fig. I.)
I have found what I take for this species occasionally at Lyttelton, but always small. It answers well to the description, except that the grooves between the ribs are smooth.
Cantharidus pupillus. The dentition resembles that of the last species, but the central tooth is slightly broader in proportion. (Pl. VII., fig. K.)
Cantharidus huttonii. Animal. Foot white or yellow, thickly marked with blue-black, concentric, interrupted, lines. Head black with three white triangular marks on the vertex between the tentacles; rostrum black, broadly margined with bright yellow or white, with black, concentric, interrupted lines like the foot. Tentacles fringed; white with a black longitudinal line. Eye peduncles short, white. Side lappets white, fringed on the left side, smooth on the right. Filaments three on each side, like the tentacles. The animal is very slow in its movements, and varies much in colour.
Dentition.—The central tooth is as broad as long, and has a minute cutting point; the central lobe is nearly obsolete. The first four laterals have a single, large, sharp cutting point, which is denticulated at the inner base. The fifth lateral has a small cutting point outside the large one. (Pl. VII., fig. M.) In these respects it is like C. texturatus.
Canthaidus tenebrosus (?). I am very doubtful as to the correct determination of this shell, for although it is bluish black, transversely sulcated, the sulci whitish, and coarser than those of C. huttonii, in shape it is shortly conical, and as broad or broader than high, and when young is perforated. The largest specimen that I have seen measured .3 inch both in height and in breadth, but usually the height is .2, and the breadth .23. It is not uncommon on seaweed in Lyttelton Harbour. Perhaps it may be a variety of C. pupillus.
Animal. Foot blue black, concentrically speckled or striped with yellowish white. Proboscis blue black, narrowly bordered with dusky white or yellow. Eye peduncles short. Tentacles purple, with a dark line down the middle. Filaments purplish, three on each side.
Dentition like C. huttonii, but the central tooth has the median lobe behind well developed. (Pl. VII., fig. L.)
Doris wellingtonensis. Dentition. The radula is folded longitudinally along the central line, the two halves being in apposition, and has about thirty-four transverse rows of teeth. The teeth are about 65–1–65. The central tooth is small and blunt; the laterals have a long, narrow, oblique base, turned over and bearing a narrow, acute, cutting point. They increase in size from the centre to about the thirtieth longitudinal row, and then decrease outwards. The cutting points are much worn in the anterior rows. (Plate VI., fig. G.)
Æolis plicata, sp. nov. (Pl. VI., fig. I.) Head, neck, and body white; branchiæ in close transverse rows on the back, dark brown, each margined with white. Body not tapering behind. Margin of foot fringed and crumpled, except near the head, where it is simple; it is divided in front, but not produced. On the side, below the branchiæ, several rows of small white papillæ (?) arranged in festoons. Tentacles distant, subulate, tapering, projecting outward, white. No eyes. Oral tentacles shorter, thickened at the base, tapering, projecting laterally, and curved backward; white. Length about three quarters of an inch.
Found on the roots of D' Urvillæa utilis, cast upon the beach at Sumner.
Dentition, 0–1–0. About 17 or 18 teeth on the radula, in a single series. Each tooth crescent shaped, with a pointed tooth in the centre, and six smaller denticles on each side (Pl. VI., fig. F. a.) Jaws two, the apices acute and denticulated, the posterior portion flattened. (Pl. VI., fig. F. b.)
Æolis corfei. The teeth of this species resemble those of Æ. plicata, they have a central tooth with six denticles on each side. There are 18 or 19 on the radula. Jaws two, the apices denticulated; the posterior portion reflexed. (Pl. VI., fig. E. a and b.) This species should I think be put into
Æolis, instead of into Montagua, as the branchiæ are tolerably crowded. On Pl. VI., fig. K, I have given a sketch of the anterior portion of the animal from below, showing the lateral processes at the end of the foot.
Description of Plate VI.
Octopus maorum. Teeth . 80. a second lateral detached.
Ommastrephes sloanii. Teeth . 80. a second lateral detached.
Cominella funerea. Teeth . 150.
Euthria lineata. Teeth . 150.
Æolis corfei. a. tooth . 150; b jaw × 16.
Æolis plicata. a tooth × 150; b jaw with radula . 16.
Doris wellingtonensis. Teeth . 80. The numbers indicate the number of the longitudinal row of that tooth from the centre. The central tooth has no number.
Struthiolaria papulosa. Teeth, detached, . 80.
Æolis plicata. Animal . 2.
Æolis corfei. Anterior extremity of animal from below.
Description of Plate VII.
Trochita novæ-zealandiæ. Teeth . 140.
Fossarina varius. Teeth . 280.
Fossarina varius. Operculum . 8.
Littorina cincta. Teeth . 280.
Littorina cærulescens. Teeth . 280.
Janthina communis. Teeth . 80. a an anterior tooth; b a posterior tooth.
Turbo smaragdus. Teeth . 80. a central tooth: b first lateral; c fourth lateral; d the same, side view; e first marginal; f the same, side view; g second marginal; h a middle marginal; i an outer marginal.
Zizyphinus punctulatus. Teeth . 80. a central tooth; b a lateral; c first marginal; d second marginal; e an outer marginal.
Cantharidus texturatus. Teeth . 160. a central tooth; b first lateral; c fifth lateral; d first marginal.
Cantharidus pupillus. Central tooth . 160.
Cantharidus tenebrosus. Central tooth . 160.
Cantharidus huttonii. Teeth . 160. a central tooth; b first lateral; c fifth lateral; d first marginal.
Anthora tiarata. Teeth . 160. a central tooth; b first lateral; c a marginal.
Columbella choava. Animal.
Columbella choava. Portion of radula with teeth. 470