159 



spherical iban that of the C similis. Cabinet of the Boston 

 Society of Natural History. 



Cyclas aurea. C. testa magna, solida, forti, elongata, glo- 

 bosa, complanata, subinequilaterali, postice subtruncata, lineis 

 increment! fortiter instructa, umbonibus magnis, perelevatis. 

 Dentibus fortibus. Long. 0.61 ; lat. 0.46 ; diam. 0.40 inches. 

 Hob. Lake Superior. 



Shell large, strong, elongated. Color greenish yellow, inte- 

 rior blue. Striations not regular. 



Remarks. The outline of this species somewhat resembles 

 that of the C. similis of Say, but otherwise it is difTerent. Cabi- 

 net of the Boston Society of Natural History. 



Cyclas inornata. C. testa subglobosa, elongata, subequi- 

 laterali, postice subtruncata, lineis incrementi irregulariter in- 

 structa, umbonibus magnis, non tumidis. Long. 0.51 ; lat. 0.13; 

 diam. 0.31 inches. Hah. Illinois. (Haldeman.) 



Shell rather inflated, irregularly striated. Color light brown. 



Cyclas simplex. C. testa parva, fragili, compressa, ine- 

 quilaterali, postice subtruncata, umbonibus magnis, elevatis. 

 Long. 0.40; lat. 0.32; diam. 0.26 inches. Hah. Illinois. 

 (Haldeman.) 



Shell small and delicate: beaks high, rather inclined anteri- 

 orly. Color light yellow, striations fine. 



Cyclas modesta. C. testa tenui, complanata, inequilaterali, 

 postice dilatata, umbonibus magnis, elevatis. Long. 0.41 ; lat. 

 0.36 ; diam. 0.25 inches. Hah. Pennsylvania. 



Shell rather fragile, somewhat elongated ; beaks very promi- 

 nent. Color yellowish green, striations hardly visible. 



Cyclas fabalis. C. testa depressa, forti, solida, elongata, 

 postice brevi et subtruncata, epidermide fusca, striis incrementi 

 fortiter instructa, umbonibus parvis, non elevatis. Long. 0.47 ; 

 lat. 0.35 ; diam. 0.24 inches. Hah. Lake Superior. (Agassiz.) 



This beautiful species is totally unlike any species heretofore 

 known, but seems to be very nearly allied to the C. castanea 

 Nobis, from the Wabash. Interior light blue. Teeth strong. 



Cyclas castanea, C. testa depressa, brevi et subtruncata, 



