176 BRITISH MOLLUSKS. 



under the head of Ckondropoma. It can hardly be said that there 

 are more than two other species in Europe, though more have been 

 described, — one, C. costulatum, in the neighbourhood of the Cas- 

 pian Sea, and another, C. sulcatum, which is diffused abundantly 

 throughout the south of France, Italy, Spain, and the islands of the 

 Mediterranean, passing into North Africa. There are, however, 

 five or six small species, of a form allied to Cy do stoma, known as 

 Pomatias, which are tolerably abundant in France, but do not ap- 

 pear on this side of the English Channel. 



There is no Cyclostoma indigenous to the United States. Al- 

 though our land and freshwater mollusks are mostly gencrically 

 represented in North America, either by species nearly allied, or 

 by species locally distinct, the only Cgclostoma that has found its 

 way into that country is the C. dentatum, a Cuban species of a 

 pupoid West Indian type, which has become naturalized in woods 

 and open places about Key West, Florida. 



The animal of Cyclostoma is distinguished in a remarkable 

 manner by this proboscis-like extension of the head, of which it 

 not unfrequently avails itself when crawling ; and the foot is peculiar 

 in being obtusely lobed in front. It was observed by Eossmassler 

 that the foot is composed of two longitudinal portions, one of which 

 advances, when the animal is in motion, while the other remains 

 adherent ; and Mr. Binney notices that it is contracted in an undula- 

 tory manner, the shell being suddenly jerked forward with each con- 

 traction. Attached to the hinder part of the foot is the operculum, 

 which has a nucleus in the centre analogous to the apex of the shell, 

 and is composed of five horizontal coils corresponding to the shell's 

 five whorls. We have said that the operculum is an apparatus be- 

 longing more especially to the water moUusk. Cyclostoma lives 

 chiefly in the vicinity of water ; not in wet places, but at the roots 

 of shrubs near the sea-coast, and it has been observed, that the pul- 

 monary vessels are here and there closer together, forming flexuous 

 ridges, which are supposed to be rudimentary gills. The position 

 of the eyes is more outward than in the inoperculated water snails, 

 and in the operculated water snails, between which groups Cyclo- 

 stoma is intermediate, it is more outward still. 



Our single British Cyclostoma is — 



1. elegans. Shell ovately turbinated, solid, of five finely corded 

 whorls, frequently articulated with livid red-brown dots. 



