Sterki: North American Sph.eriid.-e. 435 



Fossil. — Goat Island, Niagara, collected by Miss J. E. Letson, 1900 

 (No. 2224a). 



14. Sphaerium acuminatum (Prime). 



Cyclas acuminata Prime, Boston Proc, IV, 1851, p. 155; synonym of Spharium 

 striatinum, Mon. Corb., 1865, p. 37. Cf. Nautilus, XXVI, 1913, p. 139. 



It should be stated in addition to the foregoing synonymy that T. 

 Prime himself acknowledged C. acuminata as a species, and C. alhula 

 as a synonym for it in a catalog of 1853. 



Habitat. — Region of the Great Lakes, common and variable. 



Fossil. — Illinois. 



15. Sphaerium vermontanum Prime. 



Sphcerium vermontanum Prime, Proc. Acad. Nat. Sci. Philada., 1861, p. 128; Alon. 

 Corb., 1865, p. 42. 



Habitat. — Lakes Champlain and Nephremagog, Vermont, according 

 to Prime. The species is insufficiently known. In July, 1914, Mr. 

 William F. Clapp collected a large number of specimens in Lake 

 Champlain near Chimney Point, Vermont, by dredging, and these 

 appear to belong to the present species, but do not quite agree with 

 Prime's description and figure, being smaller, less inflated, and with 

 the beaks not so prominent. They may represent a lacustrine form. 

 Specimens which may belong to S. vermontanum have been seen from 

 Maine, Quebec, and Ontario. 



16. Sphaerium striatinum (Lamarck). 



Cyclas striatina Lamarck, An. sans Vert., V, 1818, p. 560. 



SphcBrium striatinum Prime, Mon. Corb., 1865, p. 37. (Minus some synonyms.) 



Cyclas edentula Say, teste Prime. 



Very variable, and still difficult to define as a species. Besides, 

 almost every Sphcerium has been named "striatinum," and there are 

 many thus misidentified lots in collections. 



Habitat. — East of the Rocky Mountains. The center of distribu- 

 tion appears to be in the Middle States, Ohio, Michigan, Indiana, and 

 Illinois. Typical or near-typical forms have not been seen from the 

 South. 



Fossil. — Michigan, Illinois, Ohio. 



17. Sphaerium striatinum corpulentum var. nov. 



Mussel large, high, well inflated, the surface often having rather 

 coarse striae; shell and hinge rather strong. 



