1892.] TJnionidoz of Spoon River. 497 



round files, etc., a bit of the sky-tinted edge would be worked 

 into a set, and this would sometimes be further enriched by the 

 addition of a silver moon and stars, making a very pretty and 

 unique ornament that would readily bring the maker one or 

 two dollars. 

 U. multipUcatus Lea. 



This species seems to me to be identical with U. undulatus 

 Barnes, and U. heros Say. It is not common in Spoon river, 

 but grows to an extraordinary size. Specimens have been 

 taken eight and a half inches long, and weighing several 

 pounds. It is indeed a hero in size. 

 U. ligamentinus Lamarck. 



A numerous species, and growing very large ; nacre always 

 a pearly white in this locality. Some shells received from 

 Wisconsin show a pink-tinted nacre. From a shell of this 

 Unio, I took a year ago, one of the finest pearls that I have 

 ever seen, a perfect oval, as large as a small white bean. 

 U. oecidens Lea. 



Quite common, and the handsomest Unio in Illinois ; no two 

 are alike, there being as great a variety in their markings as 

 there are shells. About one in ten is of the rare pink variety, as 

 beautiful as any sea-shell. The oecidens like the anodontoides 

 is a great traveler, and I have tracked them for hundreds of 

 feet in shallow water before coming up to them. 

 U. ventricosus Barnes. 



This species is probably a synonym of the preceding, at 

 any rate if they are two distinct species they shade so inter- 

 minably into each other that I do not know where to draw 

 the line separating them. The large U. ventricosus is probably 

 the male of oecidens. 

 V. capax Green. 



Several specimens that I have sent out as oecidens, have 

 been pronounced by competent conchologists as the above 

 species. But»as yet I doubt the correctness of their diagnosis 

 and do not believe the true capax is to be found in Spoon 

 river. 



