and Description of a new Genus. 241 



and Deshayes' species^ Nos. 2, 9, 40, 41, 42, 43. But since all 

 these, on account of the regularly continuous peristoma, can be 

 classed with none of the other genera of the family Helicidce, 

 and on account of the structure of the animal can far less 

 be referred anywhere else, I conceive that they form of them- 

 selves a good genus, and propose for this the name Cylin- 

 drella, — a name which in the first place points to the form of 

 all the species known, modified by the termination already 

 in use in molluscous genera. 



The characteristic of this new genus would be as follows : — 

 Cylindrella, L, Pfr, — Animal heliciforme. Testa sub- 

 cylindracea, imperforata, multispirata, saepe truncata. Peri- 

 stoma continuum, suborbiculare. Operculum vel clausium 

 nullum. 



All hitherto known species are inhabitants of the West In- 

 dian Islands, and I myself have found in Cuba four evidently 

 distinct species, of which two have already been described and 

 figured by Ferussac {Helix Cochlodina perplicata and subula), 

 the two others are perhaps new. The latter have been pre- 

 liminarily described by me inWiegmann'sArchiv(1839, p.353.) 

 under the name Clausilia elegans and crispula. It appears 

 remarkable to me that all the Cuban Cyclostomata with which 

 I am acquainted are always truncate, i. e. cast off the apex at 

 a certain age, and reclose the open place. Almost all known 

 species are dextral, and we should be justified in adopting 

 this as a generic character if Chemnitz's Turbo elongatus from 

 Jamaica [Clausilia Chemnitziana, Desh.) was not sinistrously 

 whorled, according to the figure and clear description. (Chemn. 

 ix. fig. 956.) In other respects this species is so nearly allied 

 to my Cyl. elegans in its habit, that we may admit with cer- 

 tainty that it likewise has no clausium, and belongs to the 

 new genus, of which the following are the hitherto known 

 species : — 



1. Cylindrella gracilicollis (Clausilia truncatula. Lam, 2.) 



2. collaris (Claus. collaris. Lam. 9.) 



3. antiperversa (Claus. antiperversa, Desh. 40.) 



4. suhula (Claus. subula, Desh. 41.) 



5. perplicata (Claus. perplicata, Desh. 42.) 



6. • CAemm/2'iaw« (Claus. Chemnitziana,De5^. 43.) 



Ann. Nat. Hist. Vol. 5. No. 31. June 1840. s 



