460 Annals of the Carnegie Museum. 



Habitat. — New England and New York to Ohio, Indiana, Ontario, 

 Michigan, Minnesota. Specimens from Montana (Pacific drainage) 

 and Oregon appear to be identical. 



Fossil. — Maine, Michigan. 



80. Pisidium subrotundum canadense var. nov. 



Mussel larger. Long. 5.5; alt. 4.6; diam. 3.4 mm. More oblique; 

 beaks more posterior; upper margin markedly straight, slightly alate 

 in front of the beaks and bounded by an angle. In shape they some- 

 what resemble P. ovum from Montana, but are less inflated and the 

 hinges are different. Some specimens in the same lot have the beaks 

 narrower and are more markedly different from P. subrotundum. 



Habitat. — Hare's Spring, Carleton County, Ontario, collected in 

 considerable numbers by Justice F. R. Latchford. Represented in his 

 collection, and in the Carnegie Museum, Xo. 7437. May be distinct. 



81. Pisidium subrotundum olofi var. no^ . 



Smaller, 2.5-3 nim. long. Shell translucent to transparent. Ap- 

 pears to be a regional variety. 



Habitat.— ^laime; Aroostook County, at various places, collected 

 in 1898 by Mr. Olof O. Nylander, e. g., Carnegie Museum, Nos. 2313 

 and 2378; Thomaston, collected by Mr. X. \V. Lermond, 1910. 



82. Pisidium subrotundum pumilum % ar. no\ . 



Rather small, variable in size, 2-3.5 mni. long. Rather high, 

 moderately inflated; superior margin nearly straight, bounded by 

 angles; the remainder of the outline short-elliptical to almost circular; 

 beaks not much behind the middle; surface with rather coarse, ir- 

 regular striae; color pale corneous, shell less translucent. 



Habitat. — Danvers, Massachusetts. Rev. I\Ir. H. W. Winkley 

 collected hundreds of specimens from a water-hole in a cemetery at 

 Danvers in 1909. Similar forms have been received from several 

 other places; Carnegie Museum No. 6133; Pennsylvania, C. M., No. 

 5729; Michigan. 



83. Pisidium inornatum Sterki. 



Pisidium inornatum Sterki, Nautilus, XXV, 191 1, p. 3. 

 Habitat. — Alabama. 



