MOLLUSC A OR UNIVALVES. 177 



one thousand feet above the sea; they were 

 adhering to the lower leaves of an aloe-like 

 plant. In the spring they burrow in the sand, 

 and lay their eggs about two inches below the 

 surface. When they hybernate, they adhere 

 so fast to the stones and plants that they can 

 hardly be taken without breaking the shell.* 

 One species, the B. decollatus, as it advances 

 in age always loses the upper volutions; but 

 whether from accident or design appears un- 

 certain. It, however, generally closes up the 

 broken end ; and the probability is that as the 

 animal enlarges in growth it recedes from the 

 smaller volutions, closes them up, and these 

 neglected portions fall off. Turton mentions a 

 colony of them being discovered in a green- 

 house in Devonshire, lodged in the earth under 

 the wood-work, whence they wandered abroad 

 in the summer. No foreign earth was ever 

 known to have been admitted into the house ; 

 and they were considered by the gardeners as 

 natives. 



Other species, particularly B. articulatus, are 



* Penny Cyclopaedia. 

 N 



