BIVALVE ^HELLS. 267 



15. Sl'H/ERIUM STRAMINEUM. 



S. testa ovata, repilariter convexa, subsequilaterali, antice pos- 

 ticeque scqualitcr convexa, fusco-virescente irregulariter sub- 

 striata; umbonibus inflatis, obtusis vix jn-ominentibus. 



Cvclas straminea, Conrod, Amer. Journ. xxix. 342. pl. 1. f. 5. 

 MM. Syn. Test. Viv. p. 220. no. 1. 

 DeKay, Zool. Neiv York, pt. 5. p. 225. 



Hab. In rivulis Alabamensibus. 



16. Sph^rium transversum. 



S. testa transversim oblonga, subovata, subaequilaterali, viridi, 

 substriata, antice rotundata, postice angustiore ; umbonibus 

 obtusis vix prominentibus. 



Cyclas transversa, Say, Descr. Land and Freshw. Shells, p. 10. 

 DeKay, Zool. New York, pt. 5. p. 225. 



Hab. Kentucky, Americae septentrionalis. 



17. Sph^rium giganteum. 



S. testa maxima, crassa, solida, subovata, complanata, sequilate- 

 rali, elongata, postice abrupta ; umbonibus magnis, non ele- 

 vatis. 



Cyclas gigantea, Prime, Proc. Bost. Soc. Nat. Hist. 1852, p. 15/. 



Hab. In Pennsylvaniae fluviis. 



18. Sph^rium emarginatum. 



S. testa magna, crassa, globosa, tumida, obliqua, postice sub- 

 truncata, infecjuilaterali, triangulari, epidermide olivacea, tenui- 

 ter striata; umbonibus tumidis, magnis, marginibus abruptis; 

 dentibus crassis. 



Cyclas emarginata, Prime,Proc.Bost.Soc.Nat.Hist.\S52,^.\56. 

 Hab. In lacu Superiore, Americae septentrionalis. 



19. SPHiERIUM TENUISTRIATUM. 



S. testa subglobosa, complanata, brevi, subaequilaterali, postice 

 dilatata, tenuiter striata; umbonibus perelevatis; dentibus 

 par^'is. 



Cyclas cornea, Adams {non Lamk.), Cat. of Shells in his Cabinet, 

 1847. 



Cyclas tenuistriata, Prime,Proc.Bost. Soc. Nat. Hist.\S52,^. 150. 



Hab. In fluvio Tennessee dicto, Americae septentrionalis. 



12* 



