﻿296 OnoVAKIA 



mens of wiiat I believe to l)e j^eiuiine O. lens from Columbus, 

 Mississip])!. After carefully comii).ariniT tlie Unio tinkcri B. 

 H. Wright with numerous specimens of unicolor, I am forced 

 to the conclusion that the two are practically the same. I 

 have recently had an opjiortunity of examining quite a good 

 series of these shells. 



Oboxakia i.iciBii (Lea). 



Shell small, only moderately solid, inflated, oval or short ellip- 

 tical : beaks rather full in front of the middle, their sculpture 

 not seen ; posterior ridge low. somewhat rounded ; surface with 

 low. irregular concentric ridges ; epidermis generally yellowish 

 or dirty yellowish-green, sometimes of a uniform brownish 

 color in the lighter specimens, not so dark behind in the brown 

 shells ; left valve with two small, subtriangular pseudocardi- 

 nals and two laterals ; right valve generally with three pseudo- 

 cardinals, the middle one only prominent and one lateral ; beak 

 cavities not deep; muscle scars shallow: nacre whitish. The 

 female shell is produced somewhat at the post-base, and above 

 and behind the swelling there is often a shallow, wide, radial 

 furrow such as is seen occasionally in the allied species. 



Length 35, height 22, diam. 18 mm. 



Length ^2, height 29, diam. 20 mm. 



Length 28, height 24, diam. 18 mm. 



Lake Erie and streams falling into it ; southern Michigan. 



Type locality, Erie County, Michigan. 

 Unio leibii Lea, Proc. Acad. Nat. Sci. Phila., VL 1862, p. 168; 



Jl. Ac. N. Sci. Phila., VL 1866, p. 44, pi. xv. fig. 42 ; Obs., 



XL 1867, p. 48, pi. XV, fig. 42. 

 Margaron (Unio) leibii LE.^, Syn., 1870. p. 36. 

 Oboz'oria leibii Simpson, Syn., 1900, p. 601. 



I am inclined now to believe this is a valid species, certainly 

 as good as most of those of this puzzling group. Tt is always 

 small and longer than high, it is comparatively thin, and its 

 female shells are more produced in the marsupial region than 

 those of O. circuhis. The specimen from the Sequatchee 

 River. Tennessee, and others that I have seen frt)m Tennessee 



