FRESHWATER AND LAND SHELLS. 95 



Continuation of Mr LecCs Paper. Read, July 21s/, 1837. 



Unio Rangianus. Plate XVIII. fig. 56. 



TesLa obliqua, subcompressa, valdh in(Equilaterali ; valvulis subcrassis ; natibus prominen- 

 tibus ; dentibus cardinalibus parvis ; lateralibus longis rectisque; margarita alba. 



Shell oblique, somewhat compressed, very inequilateral; valves rather thick; beaks 

 prominent; cardinal teeth small ; lateral teeth long and straight; nacre white, 



Hab. Ohio River, near Cincinnati. T. G. Lea. 



near Poland, Ohio. Dr Kirtland. 

 My Cabinet. 

 Cabinet of Mr Hyde. 

 Cabinet of Dr Kirtland. 

 Diam. .8, Length 1-2, Breadth 1-8 inch. 



Shell oblique, somewhat compressed, flattened before the umbonial 

 slope, very inequilateral ; substance of the shell rather thick before, 

 thinner behind; beaks prominent; ligament rather short; epidermis 

 yellowish, covered with numerous green rays ; cardinal teeth small ; 

 lateral teeth long and straight ; anterior cicatrices distinct ; posterior 

 cicatrices confluent ; dorsal cicatrices placed on the inferior part of the 

 cardinal tooth; cavity of the shell small; cavity of the beaks angular; 

 nacre white. 



Remarks. — This shell has been known to our naturalists for some 

 years, and has usually been considered a variety of U.perplexus (nobis), 

 without the tubercles. In some of their characters they agree entirely, 

 and the female, in both, has the same spreading out of the posterior 

 inferior portion, which is usually of a darker green. It is a smaller 

 shell than perpkxus, and may be distinguished at once by its want of 

 tubercles and by its having nearly equidistant distinct marks of growth 

 which are scarcely visible in the other. In some of its characters it re- 



