8 



remote localities, specimens from south Alabama 

 perfectly resembling others from the waters of Indi- 

 ana. 



UNIO FLEXUOSUS. 



Plate IV.— Fig. 2. 



DESCRIPTION. 



Shell subtriangular, bifurcated, swelling and sub- 

 nodulous in the middle; posterior side with a wide 

 oblique furrow; umbonial slope obtusely carinated; 

 umbo flattened, prominent; epidermis with numerous 

 slender rays; within white, cardinal teeth direct, 

 sulcated; lateral teeth short and thick. 



SYNONYMES. 



U. flexuosus, Raf. Ann. gen. des Sc. Phys. vol. v. p. 40. 

 U. foliatus, Hildreth. Silliman's Journ. vol. xiv. p. 248, fig. 



16. 

 Cab. A. N. S. No. 1050. 



OBSERVATIONS. 



A specimen of this shell in Mr. Poul son's cabinet 

 was labelled by Rafinesque, whose description, un- 

 der the name we have adopted, entirely accords with 

 the species before it has attained its profound bifur- 

 cation. 



This singular species, when young, is smooth, and 

 simply emarginate behind the middle. It approaches 

 nearest to U. gibbosus, Raf. Not uncommon in the 

 western rivers. 



