458 Annals of the Carnegie Museum. 



69. Pisidium minus (Adams). 



Cy das minor C. B. Adams, Boston Proc, I, 1841, p. 48; Prime, Mon. Corb., 1865, 

 p. 68, as synonym of P. abdiinm. Cf. Sterki, Nautilus, XXVI, 1912, p. 7. 

 Habitat. — Maine, Massachusetts, Ontario, New York, District of 

 Columbia. 



70. Pisidium alleni Sterki. 



Pisidium alleni Sterki, Nautilus, XXVI, 1912, p. 9. 



Habitat. — Maine, New Hamsphire, New York; Wisconsin (?). 



71. Pisidium roperi Sterki. 



Pisidium roperi Sterki, Nautilus, XII. 1898, p. 77. 



Habitat. — -New England to Illinois, Minnesota, Ontario, Manitoba, 

 Alberta, Montana. 



Fossil. — Michigan. 



72. Pisidium complanatum Sterki. 



Pisidium complanatum Sterki, Nautilus, XVII. 1903, p. 79. 

 Pisidium fragillimum Sterki, Nautilus, XX, 1906, p. 18. 



Habitat. — Michigan, Wisconsin, Iowa. 



73. Pisidium strengi Sterki. 



Pisidium strengii Sterki, Nautilus, XV, 1902, p. 126. 



Habitat. — Region of Great Lakes; Ohio (also in the drainage of 

 the Ohio River) ; Maine, Maryland. 



Fossil. — Michigan. 



74. Pisidium politum Sterki. 



Pisidium politum Sterki, Nautilus, IX, 1895, p. 75. 



Habitat. — -New York, Pennsylvania, Ohio, Ontario to Illinois and 

 Minnesota. 



Fossil. — Michigan. 



75. Pisidium politum decorum var. no v. 



Mussel smaller, slighter; shell more translucent to transparent, pale 

 corneous to nearly colorless. May be distinct. 

 Habitat. — Ohio, Indiana, Michigan, Illinois. 



76. Pisidium streatori Sterki. 



Pisidium streatori Sterki, Nautilus, XIV, 1901, p. 100. 



Variable; some regional forms arc markedly different from each 

 other. 



Habitat. — -New York, Ohio, Indiana, Michigan, Ontario, Maine. 



