BIVALVES. SPONDYLUS. 47 



masses; and sometimes attached to shells. They are to 

 be met with in the American, Indian, Mediterranean, 

 and other seas. 



SPONDYLUS.— r/ior»j/ Oyster. 



Gaedaropus — Thorny Oyster. Palmatus — Palmated. 



Regius — Royal. Spathuliferus — Pied. 



Aurantius — Orange. Ducalis — Ducal. 



Citreus — Citron. Anacanthus — Spineless. 



Histrix — Hedge-hog. Plicatus — Cat's Paw, 



CHAM A. — Clamp, Clam, or Shell. 



Animal — a Tethys: Shell bivalve^ rather coarse: hinge 

 with a callous gihhositi/, obliquely inserted in an ob- 

 lique hollow; anterior slope closed. 



This genus is by no means numerous, containing only 

 twenty-five species, which, for the most part, are rough 

 and uncouth looking shells. The C. cor is, however, an ex- 

 ception, it being usually smooth: from its beauty and pe- 

 culiarity of structure, it is signahzed from every shell in 

 the numerous catalogue of Bivalves. This species, which 

 varies in size from two to five inches in diameter, bears 

 a strong resemblance to a heart ; its top being surmount- 

 ed by beaks which wind round towards the hinge in the 

 most graceful curvature possible. 



The genus Chama affords a subject for amazement ra- 

 ther than admiration, for some of its species grow to an 



