45 



UbIo spatuiatns. Lea. Shell rather thin, long ante- 

 riorly ; beaks not prominent. Color greenish, myed 

 with darker greenish lines. Within, white. Shell 

 strongly spatulate. Length, two and a half inches. 

 Very abundant in Fox river. 



iTni* soiidiis. Lev. This shell is heavy, and of a 

 brown color without ; within, pink. It resembles U. 

 mytiloides, but unlike the latter has no depression 

 in its posterior slope. Loc. Illinois River. 



Unio tul,erculat«s, Barnes. Shell from five to eight 

 inches long, heavy and tuberculated over its entire- 

 exterior surface ; wliite within, brown without. Abund- 

 ant in the Illinois river. 



unio f rianguiariii, Barnes. A small triangular shelly 

 marked with green and black spots and lines. Loc. 

 Illinois river. 



unio trigonu.. Lea. Shell heavy and solid, some- 

 what resembling the undatus, Barnes, from which, 

 however, it differs in the beaks, and is also more ang- 

 ular. Loc. Illinois river. 



i;«io u«d«iat«H, Barnes. Shell oblong, with from 

 four to five undulations running towards the anterior ; 

 UTTibo far back and low. Color within, bluish-white, 

 perlaceous. Length, five to seven inches. Vermillion 

 and Illinois rivers. 



