FAMILY COLIMACEA. 37 



Vitrina pellucida. (Slightly enlarged.) 



Genus I. VITRINA, Draparnaud. 



Animal ; body elongated, carrying a lightly- whorled glassy shell, 

 mantle produced in front into a conspicuous fleshy shield, with 

 the respiratory orifice behind it to the right, beyond the respi- 

 ratory orifice reflected on the lip of the shell is a separated lobed 

 extension of the mantle reaching nearly to the apex, tentacles 

 rather short. 

 Shell ; snbglobose, thin, pellucid, glassy, smooth, imperforate, com- 

 posed of three rapidly increasing whorls. 

 The passage of affinity between the Slug and the Snail is illus- 

 trated in an interesting manner by this bttle mollusk, our figure of 

 which is from a drawing made from the life, on a slightly enlarged 

 scale, by Mr. Berkeley. The genus Vitrina, ranging throughout 

 the eastern hemisphere, is represented by about eighty species, ah 

 producing a smooth greenish-olive glassy or horny shell of singular 

 uniformity of character, except in some half-dozen species forming 

 the genus Peltella of Webb and Van Beneden, in which the base of 

 the shell is so imperfectly membranaceous as to break away in its at- 

 tachment to the animal. Six are European, but only one of these, 

 V. pellucida, is a native of the British Isles. Africa, south, east, 

 .and west, contributes fifteen species distinct from the European ; 

 Madeira has three species, of which two are of the Peltella section ; 

 the Philippine Islands have fifteen, Ceylon five, India eight, Bur- 

 mah and Siam four, Borneo, Malacca, and Celebes four, Tasmania 

 and Axxstralia seven, and New Caledonia and the neighbouring isles 

 three. In the New World, the transition between the non-spiral 

 and the spiral-shelled mollusk is more abrupt. Beyond a single 

 small species in the United States, so like our own little V. pellucida 

 that it is only lately Dr. Gould has ventured to consider it distinct, 

 there is no other record of the genus in its typical form. At Mexico 



