1836.] Fluviatile Shells from Silhet. 355 



College and the Botanic Gardens, as well as on the opposite side of the 

 river ; but specimens of deserted shells were taken by a friend, as 

 low down as the junction of the Damoda with the Hooghly. 



It is only of late that French natm-alists have verified the terrestrial 

 habits of the genus. The present species is much distressed when 

 thrown into water, and crawls out of it when immersed. Its decidedly 

 amphibious companion, Assiminia Gangetica, I have met with, on 

 dewy mornings, more than a furlong from the river's bank, crawling 

 among moist grass. 



15. Cyclostorna involvulus. (Muller.) 



This elegant species, which is abundant in a living state at Rajma- 

 hal, Secrigally, and Patharghata in JBehar, attains a large size in the 

 Silhet collection. When adult it is always possessed of a beautiful 

 orange colour on the peristome. It is Cyclostorna torquata of Lieut. 

 Hutton, J. A. S. vol. iii. page 82, and is the species alluded to by 

 me in vol. i. page 12, in my remarks on the genus Pterocyclos. 



16. Cyclostorna zebrinum. Testa albida, strigis plurimis rufo- 

 custaneis, angulato-flexuosis picta, spira depressiuscula, acuminata ; 

 anfractibus plicis paucis trans versalibus distantibus, ultimo rugis un- 

 dulatis longitudinalibus sculptis ; carina media subacuta. Apertura 

 ampla, peritremate reflexo ; umbilico parvo. Epidermide crassa, fusca, 

 plicis longitudinalibus, his setis fortibus munitis, instructis. Diam. 

 10.35 poll. 



I was at first disposed, from a consideration of the habit of this 

 shell, to view it as a variety of a Tenasserim shell, described by Mr. 

 G. B. Sowerby in the 5th volume of the Zoological Journal under the 

 name of Cyclostorna perdix ; but a careful comparison with specimens 

 which Mr. Sowerby had kindly presented to me, has enabled me to 

 distinguish it as a separate species. It differs in its sculpture, in its 

 more developed keel, more contracted umbilical cavity, and in the 

 possession of a singular epidermis, of which Mr. Sowerby's speci- 

 mens of C. perdix, though one was taken alive at Tenasserim, appear 

 to have been destitute. In the latter species the markings are white 

 mottled on a chestnut ground ; in zebrinum they consist of distant 

 zigzag flames of light chestnut on a white ground. 



17. Pterocyclos hispidus. Spiraculum hispidum, Pearson, Journal 

 of the Asiatic Society, vol. ii. p. 391. 



The acquisition of several live specimens of this genus (established 

 by me in the first No. of the Journal) during the last rainy season, at 

 the hill of Patharghata in Behar, where I first met with dead speci- 

 mens of P. rupestris, enables me to disprove the conjecture of Dr. 

 Pearson that a branchial apparatus or projecting syphon is attached 

 2 z 2 



