LIMNEA UMBROSA. 25 



Color various shades of brown, or reddish- 

 brown; sometimes with light longitudinal lines, 

 as in figue 6: the submargin of the peristome 

 is frequently chesnut. 



Geographical Distribution. " It inhabits, 

 in considerable numbers, the ponds and tranquil 

 waters of the Missouri, in the vicinity of Council 

 Bluff; and Dr. Bigsby obtained specimens in 

 Rainy lake and Seine river of Upper Canada." 

 Found in New York, Ohio, Indiana, and Illi- 

 nois. 



OBSERVATIONS. 



This shell is more ventricose than in any of 

 the allied species, and the fold upon the colu- 

 mella is liable to considerable variation, being 

 well marked in some individuals, and nearly 

 obsolete in others. In some shells the apex is 

 much elevated (the shell being in the normal 

 position) because the plane of the aperture 

 forms a large angle with the axis. Figures 

 2 and 7 represent this character largely de- 

 veloped. 



The name first given to this species by Say 

 was preoccupied, which led him to redescribe 

 it under the one by which it has since been 

 known. 



j 4 



