SCIENCE-GOSSIP. 



171 



89/ the posterior aspect of both armatures ; all 

 three figures are enlarged. Figs. 8ga-c show the 

 entire shell in three different views, all of natural 

 size. 



Plectopylis cairnsi ( 2 ) (figs, goa-g). I base this new 

 species upon a single unnamed specimen received by 

 me from Mr. Robert Cairns, to whom it was sent 



Fig. 90. — Plectopylis cairnsi. 



by a correspondent in Singapore. Nothing is known 

 of its origin, but the shell, which is somewhat de- 

 corticated, appears to have come in contact with 

 red colouring matter, so that it is not improbable 

 it was imported with dye material from Burma, 

 which country, judging from the characters of the 

 shell, may reasonably be supposed to be its native 

 place. At first I was inclined to refer the speci- 

 men to Plectopylis achatina, but its more rounded 

 contour led me to suspect that it was an un- 



( 2 ) Plectopylis cairnsi, n. sp. (figs, goa-g), shell sinistrorse, 

 discoid, solid, widely umbilicated, yellowish corneous, finely 

 and regularly ribbed, and decussated with microscopic spiral 

 lines. Spire depressed, apex scarcely prominent, suture 

 distinctly impressed ; whorls five and a-half, tumid above, 

 rounded below, increasing slowly and regularly, the last de- 

 scending moderately in front ; aperture oblique, cordate, a 

 little inflexed at the upper outer margin. Peristome white, 

 strongly thickened and reflexed; the margins united by a 

 strong raised flexuous ridge on the parietal callus, notched 

 at the junctions above and below. Parietal wall with a 

 strong median fold, given off from the apertural ridge, 

 revolving round about a quarter of the last whorl, but inter- 

 rupted at the middle ; near its posterior extremity occurs 

 a branched fold in the form of the Greek letter A, i.e. an 

 obliquely ascending fold, having anteriorly at its lower ex- 

 tremity a slightly ascending ridge and posteriorly a short 

 support ; it is deflexed horizontally at its upper extremity, 

 and at about its middle it gives off an obliquely descending 

 arm, which deflects horizontally at its lower extremity. 

 Palatal folds, five : the first, thin, horizontal, near the suture, 

 a little indented and reflexed opposite the upper extremity of 

 the oblique parietal fold ; the second, horizontal, a little 

 shorter and deflexed posteriorly, provided with a small den- 

 ticle a little above its posterior extremity ; the third, still 

 shorter, but broader, horizontal, crescent-shaped, its con- 

 cave side towards the fourth, which is vertical, very strong", 

 inclined towards the aperture ; near its lower extremity on 

 the posterior side occurs a minute dentiple ; the fifth is 

 horizontal, short and very thin. — Major diameter, i8'5 milli- 

 metres; minor diameter, 15-5 millimetres; altitude, 6 milli- 

 metres. — Habitat, probably Burma. — Type in my collection. 



described form, and this suspicion was confirmed 

 on my opening the shell, for I then found the 

 armature to constitute a connecting link between 

 that of the groups of P. achatina and P. ponsonbyi. 

 I have much pleasure in dedicating this new species 

 to Mr. Cairns, who was kind enough to allow the 

 specimen to pass into my collection. P. cairnsi is 

 flatter and more rounded in outline than P. achatina; 

 the whorls are more rounded and not angulated, 

 the last whorl widens less at the aperture, the 

 suture is more impressed, the umbilicus less deep, 

 and the peristome is white. The parietal armature 

 differs from that of P. achatina and its allies in the 

 median fold being interrupted in the middle and 

 separated from the branched portion which is in 

 the form of the Greek letter A, and in the total 

 absence of the horizontal fold near the lower 

 suture (see fig. god, enlarged, which shows the 

 parietal wall with its folds). In the palatal arma- 

 ture there are also some minor differences : the 

 first horizontal fold is indented opposite the upper 

 arm of the branched parietal fold, a feature I have 

 not observed in any other species ; the vertical 

 plate is also much narrower than in P. achatina, 

 leaving more space for the soft parts of the animal 

 to emerge (see fig. 90c, which shows both armatures 

 from the anterior side, and fig. 90/, from the 

 posterior side, both enlarged) ; and, finally, the 

 denticle behind the fifth horizontal fold, present 

 in every other known species of the group of 

 P. achatina, is absent (see fig. gog, enlarged, which 

 shows the inside of the outer wall with the palatal 

 armature in situ). 



Plectopylis (?) iamcabensis (figs. 91a, b), from Ceylon, 

 was described and figured by Dr. F. Jousseaume 

 in the " Memoires de la Societe Zoologique de 

 France," vii. (1894), P- 2 7 s - *■ 4> f - 8 - As 1 have 



Fig. 91.— Plectopylis (?) Iamcabensis (after Jousseaume). 



been unable to obtain a specimen of this species, I 

 have been compelled to rely upon Dr. Jousseaume's 

 description, and to copy his figures of the shell. It 

 is described as follows : shell subperforate, trochi- 

 form, stout, somewhat thin, striated and surrounded 

 on the last whorl by three threadlike ridges, 

 diaphanous, shining, corneous white, apex obtuse, 

 suture impressed, crenulate; whorls seven and 

 a-half, flattened, the last angulate, not descending; 

 base more convex, radiately striate; aperture 

 scarcely oblique, subangulate, lunate; peristome 

 simple, straight, columellar margin sloping, near 

 the umbilicus narrowly dilated. Diameter, 4 milli- 

 metres ; altitude, 3 millimetres. Habitat, Nuwara, 



4 



