4 AMERICAN CORBTCULAD^I. 



Long. .4 ; Lat. .34 ; Diam. .25 inch. 

 &quot; 10 ; &quot; 8 ; &quot; 6 mill. 



Hab. South America, in the Parana River. (Cabinets of the British 

 Museum, Smithsonian Institution, and Prime.) 



Cyrena paranacensis, D ORB. Mag. de Zool. V, 1835, 44. 



Cyclas paranensis, D ORB. Voy. Arner. 1846, 567, pi. 83, f. 2325. 



Corbicula paranensis, DESHAYES, Brit. Mus. Bivalves, 1854, 231. 



This small rounded species is somewhat similar in outline to 

 some inflated species of Bphserium. It is remarkably robust for 

 its size, and I know of no species of the same genus to which it 

 has any very near affinity. Compared with C. convexa, it is 

 very much smaller, less inflated, and proportionately more solid. 



3. Corbicula Obsoleta, DESHAYES. Shell oval, trigonal, oblique, 



inflated, inequilateral, proportionately solid; anterior 

 s id e broad, short, obtuse ; posterior side subangular ; 

 beaks prominent, oblique ; valves rather heavy ; interior 

 bright violet ; epidermis olive-green, varying in shade in 

 places ; stria? heavy and irregular ; hinge-margin nar 

 row, three cardinal teeth, small, nearly parallel to each 

 other ; lateral teeth narrow, equal, the anterior tooth a 



little curvedt 

 C. obsoleta. 



Long. .70; Lat. .65 inch. 



IS ; &quot; 16 mill. 

 Hab. South America, in Uruguay. (Cabinet of Cuming.) 



Corbicula obsoleta, DESHAYES, Proc. Zool. XXII, 1854, 345. II. 

 Conch. IX, 1861, pi. 2, f. 4. 



In outline this species offers some similarity with C. rotunda, 

 it is however larger and more solid. Compared with C. con- 

 vexa it is more oblique and less inflated. 



The only specimen I have seen of this species is the one in the 

 collection of Mr. Cuming, which he kindly lent me for examina 

 tion. 



4. Corbicula rotunda, PRIME. Shell rounded- oval, somewhat 

 trigonal, moderately inflated, nearly equilateral ; anterior side a little the 

 narrower, sloping from the beaks, rounded, posterior side shorter, some 

 what abrupt ; beaks small, raised, inclined towards the anterior ; valves 

 rather higher than they are broad ; striae coarse ; hinge thick, three un 

 equal cardinal teeth ; lateral teeth nearly equal, finely striated, the an 

 terior curved. 



