176 BIVALVES. 



muricated ; * posterior slope heart-shaped, 

 closed ; margin in front deeply sinuous ; the co- 

 lour is white or yellowish, with scattered reddish 

 or purplish spots ; commonly about two inches 

 long, and three inches and a quarter inside, but 

 it sometimes occurs double this size. 



It inhabits the East Indian ocean. 



Genus ARC A.f (Plural, Areas.) 



Generic Character. Shell bivalve, equivalve, 

 inequilateral ; form various, often oblong, some- 

 times orvicular ; hinge with numerous small 

 sharp teeth in each valve, alternately inserted 

 between each other, arranged sometimes in a 

 straight, sometimes in a curved line ; beaks ge- 

 nerally remote ; ligament external. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



The shells of this genus are very readily 

 known, by their numerous small teeth. Some 

 of the species attach themselves to rocks by a 

 kind of byssus : these have always the shell more 

 or less gaping ; but the greater part of the Arks 

 live buried in the sand at a short distance from 



* Muricated, having little pointed knots, from the Latin 

 murex, the sharp point of a rock. 



f Plate IX. figures 4, 5,6. 



