and Mascarene Land-Shells. 343 



3. On the Genus Cremnoconchus (olim Cremnobates). 



As the name which I gave in 1863 to this very remarkable 

 land-shell appears to have been preoccupied for a genus of 

 fishes*, I propose to substitute for it Cremnoconchus^ '. 



Besides the type species C. syhadrensis,W. BL, a shell de- 

 scribed by Mr. Layard in the Proc. Zool. Soc. for 1854, p. 94, 

 as Anculotus carinatus, proves also to belong to the genus. 

 This shell occurs in a similar habitat to that of the typical 

 species, on a precipice at Mahableshwar, about 4500 feet above 

 the sea. 



The shell described by Mr. Layard was immature ; in the 

 adult the last whorl is angulate below the suture and at the 

 periphery. The shell is imperforate, ovately conical, with the 

 apex eroded, and 8 millimetres long by 5\ broad. 



I possess a variety of C. car hiatus with canaliculate sutures, 

 from Torna hill, about twenty miles west of Poona. At the 

 same hill I found a third undescribed form, differing from 

 carinatus in the absence of any angulation at the periphery. 



As neither C. carinatus nor the new form is perforated or 

 costulated, these characters must be omitted from the generic 

 description. 



Dr. Troschel has described the tongue of Cremnoconchus in 

 the ' Archiv fur Naturgeschichte ' for 1867 ; but I have been 

 unable to gain access to the paper. I believe the result of the 

 examination has been to confirm the position I had assigned 

 to the genus. It is necessary to state, as I find I have been 

 misunderstood on the subject, that the localities where Crem- 

 noconchus occurs are from thirty to fifty miles from the sea. 



4. On the Alycasina; and Diplommatininse. 



One of the characters pointed out by Von Martens as distinc- 

 tive of the subgenus Diancta (type Dijjlommatina constricta, 

 v. Mart.) is the presence of a constriction. It does not appear 

 to have been noticed that this character is almost universal in 

 the genus Diplommatina', but in most species it takes place in 

 the penultimate whorl, and is greatly concealed by the peri- 

 stome. Examining a series of specimens from the Indian and 

 Burmese region, I find this constriction well marked in the 

 following forms : — 



D. diplocheilus, Bens. D. pachycheilus, Bens. 



* I am indebted to the politeness of M. Crosse, in the ' Journal de 

 Conch yliologie,' and of Dr. von Martens, in the ' Zoological Record,' for 

 pointing this out. 



t Etvm. : Kpnavos, a precipice ; icoyxos, a shell. 



26* 



