FAMILY UNIONID^E 133 



they are of the Pacific type, and are not found below the site of Fort 

 Benton, so far as yet reported. It is quite evident that much scientific 

 interest attaches to a thorough knowledge of the distribution of this 

 species, with its possible relation to geologic changes and the results of 

 glaciation. It is to be hoped that any data bearing on this matter will 

 be carefully preserved and put on record by travelers and others in 

 these regions. 



Genus Unio Retzius. 



Unio complanatus Solander. 



Mya complanata SOLANDER (after Lister, t. 1 50, fig. 5), in Cat. Portland Mu- 

 seum, p. loo, No. 2190, 1786. DILLWYN, Descr. Cat. Rec. Sh., I, p. 

 51, 1817. 



Unio complanatus SIMPSON, Synopsis, pp. 720-5, 1900. 



Range. Atlantic drainage from Georgia to the St. Lawrence 

 system. Also in the Saskatchewan River. 



North shore of Lake Superior ; Lake Nipissing, etc. 



Genus Quadrula Rafinesque. 

 Quadrula plicata Say. 



Unio plicata SAY, Nicholson's Encycl., 1st Am. ed., Art Conch., pL III, fig. 



i, 1817. 



Unio crassus BARNES, Am. Journ. Sci., vi, p. 118, 1823. 

 Quadrula plicata SIMPSON, Synopsis, p. 767, 1900. 

 Unio hippopaus LEA, Proc. Am. Phil. Soc., iv, p. 163, 1845 (variety). 



Range. Mississippi drainage from Arkansas and Tennessee 

 northward ; Western Michigan, Red River of the North, Lake Win- 

 nipeg and the Saskatchewan. 



The variety hippopcea occurs in Lakes Erie, Michigan, and Win- 

 nipeg. 



Quadrula undulata Barnes. 



Unio undulata BARNES, Am. Journ. Sci., vi, p. 120, pi. n, 1823. 

 Unio costatus SAY, Am. Conch., vi, No. 41, 1834 ; not of Rafinesque. 

 Quadrula undulata SIMPSON, Synopsis, p. 769, 1900. 



Range. Mississippi and St. Lawrence drainage generally, Texas 

 and Alabama ; Red River of the North ; Lake Winnipeg ; the Sas- 

 katchewan River. 



Quadrula heros Say. 



Unio heros SAY, New Harmony Diss., n, No. 19, p. 291, 1829. CONRAD, 



Mon., xii, p. 107, pi. LIX, 1840. 

 Unio multiplicatus LEA, Trans. Am. Phil. Soc., rv, p. 70, pi. rv, fig. 2, 1831. 



Range. Nuevo Leon, Mexico ; Tombigbee River, Alabama. The 

 Mississippi system generally ; Red River of the North, Manitoba. 



