31 



OBSERVATIONS. 



This species has been sent from the west, under 

 the name of coccineus, but is so very distinct that I 

 should not otherwise have compared it with that 

 species. It approaches nearest to the polltus of Say, 

 and obliqims, Lam., but the peculiarity of the teeth 

 and greatly dilated cardinal plate, as well as many 

 other characters, forbid a union with either. Mr. 

 Hyde informs me that a great number of specimens 

 in his possession, from the Scioto river, shew the in- 

 terior to be generally of a rose colour or purple, oc- 

 casionally nearly white, and rarely salmon. Of the 

 latter Mr. Hyde possesses a specimen more beauti- 

 fully coloured than any Unio I have seen it will be 

 figured in a future number. The figure is from a 

 specimen in the cabinet of Mr. Phillips. 



UNIO PRODUCTUS. 



Plate XIV. Fig. 1. 



DESCRIPTION. 



Shell narrow-elliptical, produced, moderately thick, 

 slightly ventricose, somewhat contracted near the 

 middle; anterior side short, dilated, margin obtusely 

 rounded; basal margin sinuous; posterior side ros- 

 trated; extremity rounded, much above the line of the 

 base; ligament margin parallel with the line of the 

 base; umbonial slope obtusely carinated; umbo decor- 

 ticated, not elevated above the dorsal line; within 



