44 



SPECIES XXXVII. Obliquaria tuberculata 

 (Unio tuberculata.'] 



Shell very thick, ventricose, slightly truncated 

 posteriorly ; strewed with unequal tubercles, ex- 

 cept anteriorly ; epidermis wrinkled, chestnut 

 brown ; nacre violaceous. Length | diam. 

 T 6 T axis T 5 T of the breadth. 



A species common in the Ohio and adjacent 

 rivers ; breadth three inches at most ; animal 

 yellowish ; cardinal tooth thick ; very rugose ; 

 lamellar tooth short, carinated ifossule confluent ; 

 muscular impressions deep; nacre varies from 

 bluish to deep purple. 



SPECIES XXX VII I. Obliquaria Subrotunda 

 (Unio subrotunda.) 



Shell thick, ventricose, convex, perfectly 



rounded ; epidermis almost smooth, yellowish 



brown ; nacre bluish white. Length almost equal 



to the breadth; diam. f axis T 7 F of the breadth. 



Var. 1. maculata, strewed with dark spots. 



This species is common in the Ohio and its 

 tributaries ; remarkable by its almost equilateral 

 and not transversal form; apices prominent, 

 rounded ; cardinal tooth thick furrowed ; lamel- 

 lar tooth carinated, short, and somewhat punc- 



