436 Annals of the Carnegie Museum. 



This appears to be the really typical form, rather than the small 

 eastern mussel described by Prime in his Monograph of the North 

 American Corbicnlada:. Prime's figure does not agree with the 

 description nor with any specimens. 



Habitat. — Michigan, Ohio, Illinois, mostly in creeks. 



18. Sphaerium lilycashense F. C. Baker. 



SphcBrium lilycashense F. C. Baker, Nautilus, XII, 1898, p, 65. 



Habitat. — Lilycash Creek, Joliet, Illinois; apparently also Chicago 

 River, and Charlevoix, Michigan. 



19. Sphaerium ohioense Sterki. 



Sphcerium ohioense Sterki, Nautilus, XXVI, 1913, p. 139. 



Habitat. — Ohio River in Ohio and Indiana; Elk River, West Vir- 

 ginia. 



20. Sphaerium modestum (Prime). 



Cyclas modesta Prime, Boston Proc, IV, 1 851, p. 159; as synonym of S. striatinum 

 in Mon. Corb., 1865, p. 37. 



Appears to be distinct, and certainly is not identical with S. stri- 

 atinum Lamarck. 



Habitat. — New York to Virginia and westward; apparently occur- 

 ring sporadically in Ontario, eastern Ohio, Kentucky, and Alabama. 



21. Sphaerium flavum (Prime). 



Cyclas flava Prime, Boiton Proc, IV, 1851, p. 155. 

 Sphcerium flavum Prime, Mon. Corb., 1865, p. 43. 



Variable. 



Habitat. ^-Region of the Great Lakes. 



22. Sphaerium fabale (Prime). 



Cyclas fabalis Prime, Boston Proc, IV, 1851, p. 159. 

 Sphcerium fabale Prime, Mon. Corb., 1865, p. 40. 



Habitat. — Eastern North America. 



23. Sphaerium triangulare (Say). 



Cyclas triangularis Say, New Harmony Disseminator, 1829, p. 356. 

 Sphcerium triangulare Prime, Mon. Corb., 1865, p. 36. 



Sphcerium triangulare Pilsbry, Proc. Acad. Nat. Sci. Philada., 1903, p. 785; PI. 

 LIII, figs. 4, 4a, 3, 3a; PI. LII, fig. 3- 

 Habitat. — Mexico, Colorado (?). 



