65 



CHAPTER XIII. 



OF THE VENUS. GENUS X. 



VENUS. 



"Animal a Tetht/s. Shell bivalve, the lips incumbent at the front margin ; 

 the hinge with three teeth, all approximate, the side ones diverging from 

 the point." — Lixn. 



Xhese are mostly thick strong shells, and are easily known 

 by their large strong central teeth, having no lateral ones ; 

 most of them have three teeth in each valve under the beak, 

 as Venus mercenaria, &c. ; sometimes one of the teeth stands 

 in a contrary direction or parallel to the margin, as in Venus 

 castrensis, maculata, Erycina, &c. Many species have a 

 heart-shaped depression under the beaks, as Venus Erycina, 

 Paphia, &c. ; though some are without, as Venus castrensis, 

 decussata, &c. Some few have four teeth in one if not both 

 valves, as Venus Chione, jjectinata, divaricata, &c. Vemis 

 cdentula, which has no teeth, and Venus dejlorata, which 

 has bvit two teeth in each valve, would at least agree as well, 

 if not better, with the Tellina than with the Venus. Venus 

 Meroe agrees in the teeth, and also in the shape of the shell, 

 with Donax scrijita. It must be acknowledged that some 

 species placed in this genus approach so near to some of the 

 Tellince, if we pay regard to the teeth, while some others are 

 so much like some species of Donax, that there is considerable 



K 



