213 



extreme toughnefs of the part that covers it ; the beft me- 

 thod of effecling it, is to make a longitudinal incifion on 

 the back, with a pair of fliarp pointed fciflars. 



The animal is pofTeffed of confiderable locomotive 

 power; and when in motion, frequently contrafts the mar- 

 gin or loofe (kin into wrinkles, or folds, expofing the 

 fides of the body. 



It is in fize three times as large as its fliell, and is in- 

 capable of much contra6lion, or expanfion: at firft fight 

 might be miftaken for the animal of B. aperta, but on 

 comparifon, will be found effentially different externally, 

 and more particularly in being deflitute of the teflaceous 

 gizzard, fo remarkable in that animal. 



At the time the plate was engi^aved, we had not been 

 fortunate enough to obtain a larger fpecimen of the fliell 

 than the figure reprefents ; but have fince found it of the 

 lize defer ibed. 



In the finsfular circumftance of the fliell beincr enclofed. 

 within the animal of fome of this clafs, there is a confide- 

 rable analogy between them and the Laplyfia. The L. de- 

 pilaris poffeffes a flexible, corneous fubRance, under the 

 fkin on the back, termed a fhield ; which differs only from 

 thefe fpecies of open Bul/ce in not being of a teflaceous 

 fubffance: this is of an oval fhape, pointed at one end, 

 which turns inward, and a little to one fide, in a fub-con- 

 volut^d manner : it is marked with concentric wrinkles : 



rcolour purplilh-brown. 



This 



