54 AMERICAN CORBICULAD^E. 



Fig. 53. shell, though not very distinct ; epidermis dark greenish- 



brown ; valves slight, very convex ; cardinal teeth very 

 small ; lateral teeth strong, very much drawn up and 

 shorter than they usually are in other species. 



Long. 0.25 ; Lat. 0.20 ; Diam. 0.15 inches. 

 Hob. Barbados, West Indies. (Cabinet of Prime.) 



S. barbadense. SpTiserium barbadense, PRIME, Proc. Acad. Nat. Sci. 



Phila. 1861, 415. 



I have but one specimen of this species, which seems to be 

 closely allied to S. bahiense ; it is, however, much larger, more 

 globose, and its beaks are not as much raised. 



33. Sphaerium modioliforme, ANTON. Animal not observed. 

 Shell small, ovate oblong, moderately inflated, inequilateral, translucent ; 

 anterior and basal margins rounded, posterior somewhat distended and 

 subtruncate ; beaks inclined towards the anterior, prominent, calyculate ; 

 valves slight, convex ; epidermis dark yellow, irregularly spotted with a 

 darker color ; striae hardly visible ; teeth very small ; hinge-margin some 

 what curved, very narrow. 



Long. 0.31 ; Lat. 0.18 ; Diam. 0.15 inches. 



Hob. South America, in Brazil and Venezuela. (Cabinets of the Academy 

 of Natural Sciences of Philadelphia, Bourguignat, Gassies, Museum of Paris, 

 Michaud, and Museum at Leyden.) 



Cyclas modioliformis, ANTON, &quot;Wiegm. Archiv, 1837, 284. 



Pisidium diaphanum, HALDEMAN, Proc. Acad. Nat. Sci. Phila. I, 



1841, 53. 



Pisum modioliforme, DESHAYES, Brit. Mus. Cat. 1854, 283. 

 Pisidium moquinianum, BODRGUIGNAT, Amen. 1, 1855, 61, pi. 3, f. 13-17. 

 Cyclas moquiniana, GASSIES, Pisid. 1855, f. 9. 

 Cyclas striatella, FKRUSSAC, Museum of Paris. 

 Cyclas littoralis, FKRUSSAC, Collect. Michaud. 

 Cyclas venezuelensis, PRIME, Museum of Leyden. 

 Musculium modioliforme, ADAMS, Rec. Gen. II, 1858, 451. 



The specimen from which this description was prepared (the 

 original shell from which Mr. Haldeman described the P. diapha 

 num) is in the Cabinet of the Academy of Natural Sciences of 

 Philadelphia; it was discovered in the interior of a large 

 Ampullaria from Brazil. I have never seen G. modioliformis or 

 P. moquinianum, but judging from their descriptions and from 

 the figure of the latter, I do not doubt that they belong to this 

 species. I have had occasion to examine C. striatella and C. 

 littoralis personally. 



