170 POPULAR CONCHOLOGY. 



latter, when it commenced increasing the size 

 of its shell, threw its new whorl partly over 

 the smaller individual, which was thus enclosed 

 in a prison formed by its own shell. In this 

 instance the form of the larger specimen is not 

 much altered ; but about one half of the young 

 shell projects above the spire.* 



39. Cakocolla. — Shell flat; mouth wide, 

 not long, with a thickened lip, and generally 

 toothed within ; circumference of the whorls 



often angular; umbilicus either covered or 

 visible. Animal, having a head furnished with 

 four tentacula, the two largest having eyes at 

 the summit; foot large and oblong. — 18 spe- 

 cies recent. 



These shells, and the animals inhabiting 

 them, much resemble the Helix; the latter, 

 however, have not the edge of the whorls 



* Philosophical Trans. 1833. 



