44 



unio Occident, Lea. Shell veiy broad ; umbones 

 large, elevated; beaks recurved; surface smooth. 

 €olor yellowish, strongly rayed with green— colors 

 very bright in young shells. The thickness increases 

 with age. Old specinK^ns are ponderous. Inside, 

 pearly white. This and sevei-al other species bear a 

 very close resemblance, and may yet be referred to 

 Unis ovatus, Say. 



i.-nio oi»ii«iiiu». Lam. Tliis shell is found in the Illi- 

 nois river in connection with U7iio soUdus, Lea. 



Unio ori»icuiatw«, Hildiieth. Shell oval, quadrate, 

 olive color ; narrow radiating lines from the beaks ; 

 umbo depressed. Within, white, tinged with pink, 

 or salmon color. Shell solid. Abundant in the Illi- 

 nois river. 



Unio p««tuiat«s. Lea. Fouud in the Illinois and 

 Vei-million rivers. 



Unio p..st«io«us. Lea. Found in the same localities 

 as the preceding species. 



Unio r«bisino«««. Lea. A small rubigiuous species, 

 abundant in the Illinois and Fox rivers. 



Unio rectus. Lam. A heaA'y straight shell of a black, 

 polished exterior, pink within. Six to seven inches 

 long. Abundant in the Illinois river. 



Unio retnsn**. Lam. Shell oval, beaks curved ; strong- 

 ly setuse. Color brownish outside; white, pearly 

 within. Illinois river. 



