CORBICULA. 5 



Long. .37 ; Lat. .37 ; Diana. .25 inch. 

 10 ; " 10 ; " 7 mill. 



Hah. South America, in the Surinam River, Guyana. (Cabinets of the 

 Academy of Natural Sciences of Philadelphia and Prime.) 



Corbicula rotunda, Prime, Pr. Acad. Nat. Sc. Ph. 1860, 80. 



The only specimens I have seen of tliis species, those in Phila- 

 delphia and those in my own collection, are so worn that it is not 

 possible to form any correct idea of the color of the epidermis, nor 

 of the interior markings. Compared with G. paranensis it is 

 more trigonal, longer from the beaks to the basal margin, trans- 

 versely less broad and more inflated. It differs from G. convexa 

 in being smaller, less ronnded, higher and less inflated. 



5. Corbicula limosa, Deshayes. — Shell transverse, ovate-ellipti- 

 oal, inequilateral, compressed, somewhat tumid, com- 

 paratively solid, anterior side, narrower, posterior 

 shorter, subtruncated ; striae irregular ; epidermis 

 greenish ; valves rather strong, inside white or of a 

 deep violet ; beaks tumid, inclined towards the inte- 

 rior ; hinge-margin broad, with three unequal teeth; 

 cardinal teeth diverging, the principal ones bifur- 

 cated ; lateral teeth nearly equal in length, narrow, q Unwsa. 

 serrulated ; palleal impression terminating posteriorly 

 iu a small trigonal sinus. 



Long. .87; Lat. .68 ; Diam. .50 inch. 

 " 22; " 18; " 13 mill. 



Hub. South America, in the rivers of Eastern Uruguay. (Cabinets of 

 the British Museum, Smithsonian Institution, Cuming and Prime.) 



Tellina limnsa, Maton, Trans. Linn. Soc. London, X, 1809, 825, pi. 24, 



f. 8-10. 

 Cyrena limosa, Gray, Ann. Ph. n. ser., IX, 1825, 137. 

 Cyrena variegata, D'Orbigny, Guer. Mag. V, 1835, 44. 

 Cyclas variegata, D'Orbigxy, Voy. Amer., 1846, 567, pi. 82, f. 14-16. 

 Cyclas limosa, D'Orbigny (error), loc. sub. cit. 1846, pi. 82, f. 14-16. 

 Corbicula semisulcata, Deshayes, Proc. Zool. XXII, 1854, 343. 

 Corbicula limosa, Deshayes, Biv. Brit. Mus. 1854, 231. 



This well-marked species varies much in genernl appearance ; 

 some specimens are beautifully marked with light brown rays run- 

 ning from the beaks towards the basal margin, others do not ex- 

 hibit these markings. The epidermis of the young shell is very 



