1836.] Fluviatile Shells from Silhet. 353 



renders that species so remarkable. It belongs to the subgenus 

 Helicella of De Ferussac. The epidermis scales off like that of the 

 Solenes, whence the trivial name which I have conferred upon it. 



9. Helix Cestus. Testa, subdepressa, cornea vel fuscescente, 

 radiatim striata, subtus convexa, perforata ; spira. sub-conoidea ; apice 

 obtuso ; ultimo anfractu sub-angulato, fascia unica rufo-fusc<i, media, 

 reliquis fascia saturali cinctis; peristomate sub-reflexo. Diam. 0.65 poll. 



Whorls five. H. cestus approaches in form and colour to a species 

 which I possess from the Tyrol, and which is marked " H. zonata," 

 but which does not agree well with Lamarck's characters oiplanospira, 

 of which he gives De Ferussac's zonata as a synonym. It differs from 

 it in not having a white or a much reflected peristome. It belongs to 

 the sub-genus Helicella. 



10. Bulimus citrinus. Lamarck. 



This is the reverse variety of a handsome shell, of which South 

 America is recorded as the habitat by Lamarck. It is perforated, (of 

 which character he makes no mention,) and of an uniform yellow, 

 without bands or marks, and being weathered, no polish is observable. 

 Length one inch. 



11. Achatina tenuispira. Testa elongato turrita, corned, longitu- 

 dinaliter striata, versus apicem attenuata, columnari ; anfractu ultimo 

 interdum fasciis quibusdam albidis transversis ornato ; suturis im- 

 pressis; apice obtuso. Long. 1 poll, circiter. Lat. 0.55. 



This Achatina, belonging to De Ferussac's subgenus Cochlicopa and 

 to his groupe of Hyloides, is remarkable for the attenuated columnar 

 form of the terminal whorls of the spire. 



12. Achatina crassvlabris. Testa turrito conic&, k*vi, corned, lon- 

 gitudinaliter striata ; anfractibus convexis, suturis excavatis ; labro 

 intus incrassato ; columella praearcuata ; apice obtuso. Long. 0.7. 

 Lat. 0.3 poll. 



This shell has the habit of a Ceylon species which I believe to be 

 A. nitens of Gray. It differs in greater size, in its incrassated outer 

 lip, in its somewhat more ventricose form, and in its sculpture. It 

 approaches to Swainson's genus Achatinella in the arcuation of the 

 columella, but differs in the absence of the thickened pliciform termi- 

 nation to it, and in having the incrassation quite at the edge of the 

 outer lip, instead of removed to a little distance within it. 



13. Clausilia loxostoma. Testa sinistrorsa, fusiformi, medio ven- 

 tricosa, corneo-grisescente ; anfractibus convexis, bevigatis, striis 

 obsoletis ; suturis confortissime crenulatis ; apertura elongata. obliqua, 

 bi-plicata, supra angustiori, infra dilatata peristomate reflexo ; 

 columella prsearcuata. Long. 0.85 poll. 



2 z 



