xiv. CONCHYLIA— D/THriJJ. 



6. Petricola. — Testa subhians, dentibus duobus inter tres pene- 



trantibus. 

 Shell somewhat open, with two teeth in one valve 

 closing between three in the other. 



36. Venus. — Testa clausa, dentibus tribus inferne approximatis 



supernd divergentibus. 

 Shell closed, with three teeth which are close toge- 

 ther at their base and divergent at their tips. 



7. Venerupis. — Testa antici Mans dentibus tribus approximatis 



parallelis. 

 Shell open at the anterior end, with three teeth 

 all close together and parallel. 



37. Cytherea. — Dentes quatuor in valvd altera, unico remotiusculo. 



In one valve four teeth, one of them rather remote. 



14. Anatina. — Dentes cochleariformes, mutici. 



Teeth sj)oon- shaped without additional denticle. 



15. Listera. — Dentes cochleariformes, cum denticulis adjectis. 



Teeth spoon-shaped with additional denticles. 



54. Unio. — Dentes subconici, striato-tuberculati. 



Teeth somewhat conic, striate or tubercled. 



13. PANOPiEA. — Dentes conici, et hinc callum breve. 



Teeth conic, and a callosity on one side. 



38. Arca. — Cardo rectilinearis, dentibus numerosis. 



Hinge in a straight line, with numerous teeth. 



