134 



SCIENCE-GOSSIP. 



shell figured in Hanley and Theobald's " Con- 

 chologia Indica," t. 57, f. 8 and 9, and Martini 

 und Chemnitz " Conchylien Cabinet" (2) i. t. 66, 

 f. 28-30 (from Mergui, Burma), I also refer to 

 this variety. A specimen measuring 21 milli- 

 metres in diameter is in the collection of Mr. 

 Cairns, who also possesses four immature shells 

 in various stages of growth, all showing sets of 

 barriers similar to that of the immature PUctopylis 

 achatina shown in fig. 8ia. 



Plectopylis achatina var. venusta (-) (figs. S^a-c) 

 is smaller than any form of P. achatina I have 

 seen. It is pale yellowish-white in colour, 

 flammulated with chestnut above and at the 

 sides. It resembles the variety ohcsa in the 

 deeper umbilicus, the sloping underside and in 

 the comparative height of the shell ; the median 

 parietal fold does not quite reach the apertural 

 ridge as in that variety, and the lower horizontal 

 parietal fold is not visible from the aperture ; it 

 resembles the type in the sudden widening of the 

 last whorl. The peristome is livid brown, the 

 right margin being a little depressed ; the left 



is darker than the other forms of P. achatina, 

 except the variety infrafasciata, being of a blackish- 

 brown above, a little paler below. It is, however, 

 larger than that variety, and does not possess the 

 white band below ; the umbilicus is also much 

 deeper, the shell being in that respect more like 

 the variety ohesa, which it also resembles in the 

 sloping underside ; the aperture is proportionately 

 larger than in that variety. The spiral lines on 

 the last two and a-half whorls are visible without 



Fig. 86. — Plectopylis achatina var. castanea. 



the aid of a lens. The specimen figured was 

 received by me from Miss Linter. 



Plectopylis achatina var. brevipiica (^) (figs. Sya-f) 

 has a much shallower umbilicus, and is thinner 

 and more fragile than any other form of P. achatina 

 known to me. It is somewhat like the variety 

 infrafasciata, but it is devoid of the white band on 

 the lower side ; the last whorl also widens a little 

 more than in that variety, but is less deflected, and 



Fig. S5. — Plectopylis achatina var. venusta. 



margin is paler. The specimen figured was re- 

 ceived by me as Plectopylis pachystoma Theobald ; 

 but as I am not aware that this name was ever 

 published, and as I have seen other shells so 

 labelled, I consider it expedient to discard the 

 name altogether. A specimen in the collection of 

 Dr. von Mollendorff, likewise labelled P. pachy- 

 stoma, I am unable to separate from the present 

 variety, although it shows no flammulation and the 

 peristome is white ; in other respects it is identical. 

 Plectopylis achatina var. castanea (■^) (figs. S6a-c) 



(2) Plectopylis achatina var. veniista, n. var. (figs. Sjfl-c), 

 differs from tl:e type and the other varieties in being smaller. 

 It resembles the variety obesa in the deeper umbilicus, 

 in the sloping underside, in the comparative height of the 

 shell, and in the median parietal fold not reaching the 

 apertural ridge, but the last whorl widens more.'as in the 

 type. In colour it is pale yellowish-white, flammulated with 

 chestnut above and at the side. The peristome is livid 

 brown, the left margin paler, the right margin a little 

 depressed. — Major diameter, 17 millimetres ; minor diameter, 

 14 millimetres ; altitude, 7 millimetres.— Habitat, Burma. 

 — Type in my collection. 



(3) Plectopylis achatina var. castanea. n. var. (figs. 86n-c), 

 differs from the type in being smaller in diameter and pro- 

 portionately higher ; it is darker in colour, being blackish- 

 brown above and a little paler below. It resembles the 

 variety obesa in being more rounded in outline, in the last 

 whorl not widening suddenly at the aperture, in the sloping 

 underside, and in the median parietal fold not reaching quite 

 to the apertural ridge ; the last two and a-half whorls are more 

 strongly decussated above and below than in any other form. 



Fig. 87. — Plectopylis achatina var. brevipiica. 



An obsolete keel is visible at the periphery..— Major diameter, 

 21 millimeters; minor diameter, 19 millimetres; altitude, 8 

 millimetres.— Habitat, Burma. — Type in my collection. 



(*) Plectopylis achatina var. brevipiica, n. var. (figs. 87«-c), 

 differs from the type and all the other known varieties by the 

 much more shallow umbilicus. It resembles the variety 

 infrafasciata in outline, but it is of a uniform dark brown, 

 with a somewhat polished surface, and the last whorl widens 

 more suddenly at the aperture. The basal horizontal parietal 

 fold is very short, not extending on either side beyond the 

 two lower arms of the main median fold; the first palatal 

 horizontal fold is considerably more elevated than in the 

 other forms, and is bilobed ; the second and third horizontal 

 folds are also more elevated, the latter fold has a short fold 

 above its posterior portion ; the vertical plate is also more 

 elevated, and in place of the usual denticle posteriorly to its 

 lower extremity is an elevated ridge, quite united to the 

 plate. — Major diameter, ig millimetres; minor diameter, 

 16 millimetres; altitude, 7 millimetres.— Habitat, Burma.— 

 Type in Mr. Ponsonby's collection. 



