116 



was a small valve of this species, but it was then 

 referred as a variety to the convenient but obsolete 

 receptacle of this genus, U. crassus." Say. 



It most nearly resembles the preceding, (\ rgpAsW, 

 but may be distinguished by its more triangular ele- 

 vated outline, and more elevated umltn and ligament 

 margin. The posterior furrow is much narrower 

 the tuberculated ridge is nearest the j>osterior ex- 

 tremity, which is the reverse in U. cyphiu*. and the 

 epidermis is darker and less polished. 



Inhabits the Ohio and its tributaries. The figure 

 is from a fine specimen in Mr. PoulsonV cabinet. 



UNIO PLICATl S. 



Plate LXV. 

 DESCRIPTION. 



Shell subrhomUudal, very vcntncose; j>ostcrior 

 side x*ith large oblique irregular folds, profound about 

 the umbonial slope, and but slightly impressed on the 

 posterior slope; ligament margin parallel with the 

 base; posterior margin long, slightly oblique, rounded 

 above, and slightly emarginate towards the extremity, 

 which is obliquely truncated inwards; umlx) very 

 prominent, tumid, plicated, nearly terminal; epider- 

 mis blackish or brownish, coarsely striated; within 

 white; cardinal teeth deeply sulcated. 



