226 PEOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



One naturally turns to Adams' species to see what name he utilised 

 for the true G. Jamaiceyisis : I think his G. affinis is the same species, 

 and so that name becomes a synonym. 



The shells I now describe were collected by Mr. Jai'vis and 

 Mr. Nutt, and the species is separable, when adult, from all the forms 

 of Geomelania known to me, by the fact that it forms a second lip and 

 peristome, within and beyond the earlier one. This seems to be 

 a constant, though remarkable, character. There is a series of the 

 present form in Chitty's collection, now in the British Museum, 

 marked by him- "n.s.," but only one or two of those show the 

 duplication. Another noteworthy feature is the absence of any spiral 

 sculpture ; there is also a lack of any denticle or projection on the 

 outer margin of the peristome. 



I append a diagnosis. 



Geomelania Jaevisi, n.sp. Fig. 1. 



Shell much elongated, almost cylindrical, but tapering very slowly 

 towards the apex ; colour almost transparent white, becoming chalky 

 in appearance when dead ; sculpture, numerous well-marked ribs, the 

 latter being slightly arcuate and extending over the whole of the 

 shell; apex truncate ; whorls, seven remaining, very convex, separated 

 by a deep suture ; aperture ovate, the outer margin being well 

 expanded and reflexed, a trifle ' squared ' at the base, and without any 

 trace of denticle or projection; a well-marked callosity joins the 

 margins; the adult shell has a second lip formed in and beyond the 

 first, very similar in character. Alt. 10, diam. (penultimate whorl) 

 2 mm. 



Hob. — Near Albert Town, Trelawney, Jamaica. 



Type in my collection. 



