Land-snails 377 



The Two -toothed Door - .shell {C. hidentata) is 

 generally similar to tlie last named, but much 

 smaller (half an inch long) and more slender in pro- 

 portion. The whorls are covered with ridges in like 

 manner, but these are not so high as in hip! leaf a. 

 The mouth, too, is similar, tliough smaller, but the 

 base is rounder, less channelled tlian in the last. 

 The clausilia of the last species, this, and the next, 

 differ from that of laminata in not being notched. 

 This is a very variable as well as abundant shell. 

 On mossy walls, stone dikes, and the trunks of 

 trees throughout these islands, it may be found in 

 great numbers. Jeffreys expresses a form of astonish- 

 ment produced by specimens that were partially 

 smootli, and which Dr. Turton and himself once 

 considered to be the Continental C. jjrt?'t'u7(6. Such 

 examples are common, and if Jeffreys had examined 

 them with a lens he would have discovered that the 

 ridges are almost entirely a matter of epidermis, and 

 that where this has been removed by abrasion in 

 dragging the shell into narrow chinks, or by the 

 radula of a brother, the shell is left nearly smooth — 

 agreeing Avell with his own description of C. jKtrvida, 

 " quite smooth with the exception of some very faint 

 transverse lines, wdiicli are only observable with a 

 lens." 



Rolph's Door-shell (0. rolpJii) is about the same 

 length as C. hidentata, but of greater breadtli and of 

 thinner material, and covered with a slightly glossy 

 red-brown epidermis which is wrinkled into ridges as 

 in the last species. In many specimens the ridges 

 have almost entirely disappeared, leaving a dull dirty 

 grey surface. There are fewer whorls — nine or ten 



