92 BRITISH MOLLUSKS. 



Zua subcyliildrica. (Very much enlarged.) 



Genus YI. ZUA, Leach. 



Animal ; body oblong, obtusely rounded in front, converging to an 

 angular point behind, dingy grey, but little tubercled, carry- 

 ing a rather narrow, oblong, glossy, transparent shell, upper pair 

 of tentacles much the longer, with the bulbous extremities 

 rather lengthened. 

 Shell ; imperforate, oblong-cylindrical, of five to five and a half, 

 smooth, glossy, transparent whorls ; aperture small, lip simple, 

 callous, right margin obsoletely truncated at the end. 

 This bttle snail has been separated as a genus chiefly on account 

 of the shining vitrified surface and marginal subtruncation of the 

 shell, which somewhat partakes in these respects of the characters 

 of the little glassy Achalince of the tropics. The animal is the same 

 as that of Helix, excepting that the bulbous extremities of the ten- 

 tacles are rather more lengthened. Eisso and Jeffreys first sepa- 

 rated it from Bulimus, but included it with some others in rather an 

 incongruous medley. Dr. Leach was the first to distinguish it as a 

 genus by itself. M. Moquin-Tandon retains Zua in his genus Buli- 

 mus, adopting Bisso's appellation of Cochlicopa in a subgeneric sense. 

 Forbes and Hanley consider it entitled to be kept apart generically 

 froni Bulimus. 



Zua has the widest distribution, in space and elevation, of all 

 our land mollusks. It occurs in countless numbers, both in wet and 

 dry places, throughout the whole of the Caucasian province of distri- 

 bution — enclosing Europe, Worth Africa, and Western Asia — as 

 well as throughout the chief portion of the United States. 



1. subcylindrica. Shell imperforated, oblong, glossy, of five to 

 five and a half whorls, columellar lip obsoletely truncated at 

 the end. 



