40 AMERICAN CORBICULAD^E. 



8. Sphaerium denfatuin, HALDEMAN. Animal not observed. 



Shell large, ventricose, somewhat equilateral, 

 Fig. 32. inferior and anterior margins rounded ; posterior 



somewhat angular ; beaks large, well-rounded, dis 

 tant, not very prominent ; hinge-margin nearly 

 straight ; cardinal teeth single, distinct ; lateral 

 teeth not prominent ; sulcations slight ; epidermis 

 olive-green, with a dark narrow zone at some dis 

 tance above the basal margin. 



Long. 0.50; Lat. 0.40; Diam. 0.37 inches. 



S d ntatum Hob. North America, in Oregon. (Cabinet of 



the Academy of Natural Sciences of Philadelphia.) 

 Cyclas dentata, HALDEMAN, Proc. Acad. Nat. Sci. Phila. I, 1841, 100. 



The young shell is more elongated and more heavily sulcated 

 than the adult ; the beaks are less large and less tumid. This is 

 a well marked species, compared with -S. patella, Gould, from 

 the same section of the country, it is found to be larger, more ven 

 tricose, the beaks are more inflated, and the color of the epidermis 

 is different. 



The only two specimens I have seen of th S. dentatum were 

 those from which Mr. Haldeman described the species, an adult 

 and a young one, which he was kind enough to lend me for study ; 

 they are now deposited in the collection of the Academy of Natu 

 ral Sciences of Philadelphia. 



9. Spliaeriiim falbalis, PRIME. Animal, syphons crimson. 

 Shell transversely oval, compressed, nearly equilateral ; anterior and 



basal margins rounded ; posterior margin slightly abrupt ; 

 Fig. 33. beaks not full, very much depressed ; sulcations moderately 



heavy, very regular, quite distinct ; epidermis light-green, 

 it is, however, sometimes quite dark ; in the young it is 

 often straw color ; valves slight, interior blue ; hinge-mar 

 gin very slightly curved ; cardinal teeth small, assuming 

 the shape of the letter V reversed ; lateral teeth slight ; an 

 terior tooth somewhat more elevated, both placed very nearly on a line 

 with the cardinal teeth. 



Long. 0.56; Lat. 0.43; Diam. 0.25 inches. 



Hob. North America, in the States of New York, Ohio, Illinois, Tennes 

 see, Georgia, Virginia, Michigan and Pennsylvania. (Cabinets of Smith 

 sonian Institution, Jay and Prime.) 



Cyclas fabalis, PRIME, Bost. Proc. IV, 1851, 159. 



Cyclas castanea, PRIME, loc. sub. cit. IV, 1851, 160. 



Cijclas sulculosa, DECHARPE^TIER, MSS. 1851. 



