CYTHEREA. 



GENEUIC ClIAUACTER. 



Shell bivalve, equivalve, inequilateral, suborbicular.tri- 

 gonate or transverse ; four cardinal teeth on one valve, 

 three of which diverge from the summit and one is isola- 

 ted, situated under the luniile ; three divergent cardinal 

 teeth upon the other valve, and a fossetat a little distance- 

 parallel to the lunule margin ; no lateral teeth. 



OBSERVATrONS. 



A genus of beautiful marine shells, included by Linne 

 in the genus Venus, but separated by Lamarck in conse- 

 quence of the middle tooth of the hinge being profoundly 

 divided into two and the posterior tooth being distant and 

 parallel to the lunule edge. The name of Meretrix which 

 that author lirst applied to this genus he subsequently 

 thought proper to reject in favor of the present designa- 

 tion. An allied genus the Astarte of Sowcrby (Crassina, 

 Lam.) has but two teeth in each valve. Cyclas, Cyrena 

 and Megadesma have remote lateral teeth ; Cyprina has 

 one remote lateral tooth, and the posterior muscular im- 

 pression of Lucina is elongated. 



The species are numerous, inhabitants of almost every 



shore, and are imbeded in many fossil localities. The 



Japanese and Chinese paint and gild the innerside of C. 



lusoria with various devices and make use of it in their 



games of chance, whence its name, 

 ri. 57. 



