CHKTSALIS SHELLS. 65 



first sight, and until the eye gets accustomed to their 

 appearance, might well he mistaken for chrysalides, 

 or little excrescences of the hark. The Rev. Revett 

 Sheppard, writing of Suffolk mollusca, ohserves that' 

 " these shells, particularly in their young state, show 

 great sagacity and ingenuity, hy covering themselves 

 with an epidermis adapted to the different situations 

 in which they are found ; and, when so covered, it is 

 almost impossible for any other than a conchological 

 eye to detect them. If its abode be upon a tree 

 covered with lichens, then is the epidermis so con- 

 structed as to cause the shell to resemble a little 

 knot on the bark covered with such substances. If 

 on a smooth tree, from whose bark issue small sessile 

 buds, as is frequently the case, it will pass very 

 well for one of them ; and on a dry bank, or the 

 lower part of the body of a tree splashed with mud, 

 its appearance will be that of a little, misshapen, 

 pointed piece of dirt." 



Bulimus montanus prefers a southern aspect, and 

 ascends trees to a height which frequently renders it 



Mr. Tate, is, that this tree is resorted to by the snails for 

 the purpose of feeding upon the minute parasitic vegetation 

 with which the trunk is clothed. 



