OF THE FAMILY OF NAIADES. 435 



Hab. Ohio. T. G. Lea. 



My Cabinet. 

 Cabinet of T. G. Lea. 

 Cabinet of Prof. Vanuxem. 

 Diam. -8, Length 1.3, Breadth 2 inches. 



Shell elliptical, inequilateral, ventricose ; substance of the 

 shell thin, the rays being very visible through the nacre ; 

 beaks prominent and slightly undulated ; epidermis bright 

 olive yellow, with numerous green rays passing from the 

 beaks to every part of the margin ; slightly wrinkled, smooth 

 and glossy ; cardinal tooth double in both valves and deeply 

 cleft; lateral tooth lamelliform, nearly straight, higher near 

 the termination, termination abrupt; anterior cicatrices dis- 

 tinct ; posterior cicatrices confluent ; dorsal cicatrices situated 

 on the under part of the cardinal tooth, and within the margin 

 of the cavity of the beaks ; cavity of the beaks large and round- 

 ed ; nacre pearly white and iridescent, thin, showing the rays 

 very distinctly through it, and presenting a wide margin. 



Remarks. — This beautiful shell resembles most the young 

 cariosus of the Ohio and other western waters. It differs, 

 however, in being much less ponderous, possessing more mi- 

 nute rays, being rather more ventricose, having more elevated 

 teeth and more prominent beaks. 



8. Unio Occidens. Plate X. fig. 16. 



Testa suh-elliptica, itHEquilaterali, transversa, ventricosd; valvulis 

 crassis ; natibus sub-undulatis, raro decorticatis ; ligamento sub-brevi 

 crassoque; dentibus elevatis ; margaritu alba. 



Shell inequilateral, sub-elliptical, transverse, ventricose ; valves thick ; 

 beaks slightly undulated, rarely decorticated ; ligament rather short and 

 thick; teeth elevated ; nacre white. 



Hab. Ohio. T. G. Lea. 



My Cabinet. 



VOL. III. — 5 s 



