30 



AMERICAN CORBICULAD^. 



species. In outline it offers some resemblance with G. colorata, 

 it is, however, larger, more inflated and very much more solid. 



33. Cyrena colorata, Pkime.— Shell very small, fragile, elongated, 

 cuneiform, very inequilateral, compressed, ante- 

 ^^S* ^^* rior side broader, rounded ; posterior side longer, 



produced, subabrupt at extremity ; beaks small, 

 acute ; stri<e very fine, hardly visible ; color 

 variable, whitish with zones of purple, or 

 orange ; epidermis wanting ; hinge-margin 

 nearly straiglit, narrow, teeth small and deli- 

 cate ; cardinal teeth unequal, divergent, anterior 

 C. colorata. tooth rudimentary, posterior ones bifid ; lateral 



teeth uneqvial, elongated, narrow. 

 Long. 0.80 ; Lat. 0.52 ; Diam. 0.28 inches. 

 " 20 ; " 13 ; " 7 mill. 



Hab. Tlie West Indies, in the Island of New Providence. (Cabinets of 

 the Smithsonian Institution, Cooper, Browne and Prime.) 



The external appearance of this species presents all the charac- 

 ter of a marine shell, its denticulation, however, places it without 

 a question in the genus Cyrena. Mr. W. Cooper, of Hoboken, 

 its discoverer, found several specimens of it in a brackish pond, 

 living in company with some Gerithia. It is smaller, more fra- 

 gile, less inflated and more regular in outline than either C. jlori- 

 dana, G. salmacida or G. cubensis. 



34. Cyrena anoniala, Deshates. — Shell trigonal, very much in- 

 flated, heart-shaped, very inequilateral, strise very 

 Fig. 24. flue, regular, hardly perceptible ; epidermis light 



grayish-green ; beaks large, acute, inclined inwards ; 

 anterior side short, broadly semi-circular ; posterior 

 side extended, conical, acute and angular at ex- 

 tremity ; valves very fragile, interior grayish with 

 markings of violet ; hinge-margin rounded, verv nar- 

 row ; cardinal teeth very small, approximate, sub- 

 equal, divergent, the central tooth bifid ; lateral teeth 

 C. anomala. subequal, distant, compressed ; sinus very small, 



barely visible. 

 Long. 2.00; Lat. 1.60; Diam. 1.36 inches. 

 " 50 ; " 40 ; " 34 mil!. 



Hah. South America, in Peru. (Cabinets of Cuming and Prime.) 



Cyrena anonmla, Desh. Proc. Zool. XXII, 1854, 21. 

 Cyrena peruviana, Desu. Bivalv. Brit. Mus. 1854, 257. 



