CO^CHYLlk—DITHYRA. 36. ]39 



The outline of this shell appears to resemble tliat of the 

 Cytherea Tigeriiia ; but from the description of Montagu the 

 teeth are different, and the reticulations are coarser. 



36. VENUS— i/AW^. 



Testa transversa vel suborhicularis, (Pquirahis, ineeqtiilate- 

 Talis, clausa. Cardo dentibus tribiis, exterioribus inferne 

 approximatts siiperne dicergentibus : lateralibus nullis. 

 JAgamentum externum. 



Shell transverse or somewhat orbicular, equivalve, inequilateral, 

 closed. Hinge with three teeth, the outer ones close together 

 at the base and divergent at their tips: lateral teeth none. 

 Ligament external. 



■&' 



The Venus tribe, pre-eminent for the elegance of their figure 

 and splendor of colors, formerly so numerous and difficult of dis- 

 crimination, are now ver3' properly confined to the simple charac- 

 ters which are exhibited above : with three strong teeth in each 

 valve, one or two of which are generally cloven, all close together 

 at their insertion, and the outer ones spreading obliquely in 

 opposite directions, with the middle one straight. 



In this respect they differ from the Venerupis, which has all 

 the teeth parallel and erect. The beaks are prominent and 



T 2 



