38 AMERICAN CORBICULAD^E. 



1851. The differences existing between these shells are at times 

 quite marked, but in general characters they agree, and I am in- 

 clined to believe that these differences owe their origin solely to 

 local causes. 



I had occasion some time since to convince myself of the identity 

 of the S. striatinum with the C. edentula of Say.* 



This species, which is not unplentiful in the localities where it 

 is found, varies much in size, color, and external appearance gene- 

 rally. The shell from Connecticut is so slight, that it is nearly 

 translucent, and the strias are so light as to impart to it a lustrous 

 appearance ; on the other hand, I have specimens from the 

 Hoosack, which are quite heavy and coarsely striated ; in the 

 main, however, they all seem to tally. The variety from Alabama, 

 described as the C. tenuistriata, is less distended, is fuller, and 

 the sulcations are hardly perceptible. 



Compared with S. soJidulum, this species is smaller, more in- 

 equilateral, less tumid, more compressed, less solid, less heavily 

 sulcated, and its posterior extremity is more distended. 



6. Spliaeriuin stamineiini, Conrad. — Animal not observed. 



Shell oval, somewhat full, inequilateral ; anterior 



Fig. 30. generally abrupt ; posterior slightly distended ; beaks 



very full and prominent, widely separate at the apex, 



often eroded ; epidermis dark brownish-yellow ; striae 



/ ' \ heavy; valves strong; interior blue; hinge-margin 



curved ; cardinal teeth double, nearly obsolete ; late- 



v :^_^^-; „ ral teeth distinct, strong. 



Long. 0..5() ; Lat. 0.37 ; Diam. 0.31 inches. 



S. stmniiltum. 



Hab. North America, in the States of New Jersey, 

 Ohio, Illinois, Arkansas and Alabama. (Cabinets of the Academy of Na- 

 tural Sciences of Philadelphia, Smithsonian Institution, Conrad, Jay and 

 Prime.) 



Cyclas staminea, Coxrad, Amer. Journ. XXV, 1S34, 342, pi. 1, f. v. 



Cyclasfuscata, Rafinesque, Prime in Bost. Proc. IV, 1852, 281. 



Cyclas bulbosa, Anthony, Prime in loc. sub. cit. IV, 1852, 283. 



I have -been induced to unite to this species the G. fuscata, 

 Rafinesque, which I consider as nothing more than a large variety. 



' Notes on some American species of Cyclas, &c., by Temple Prime, 

 the Hague, 1857. 8vo. 



