16 Trans. Acad. Sci. of St. Louis. 



burg. It is reported also from the Ouachita river, near the 

 boundary of the Indian Territory, but we have seen no speci- 

 mens from that stream. The probable identity of these 

 forms, as given in the above synonymy, was suspected by Mr. 

 Lea himself ; it seems, therefore, now more than useless longer 

 to attempt their specific distinction. 



Unio ebenus Lea. 



Trans. Am. Philos. Soc, Vol. IV, p. 84, PI. IX, Fig. 

 U, 1830. 



Unio suhrotundus Lea. Trans. Am. Philos. Soc, Vol. 

 IV, p. 117, PI. XVIII, Fig. 45, 1831. 



Unio lesueurianus Lea. Trans. Am. Philos. Soc, 

 Vol. VIII, p. 195, PI. VIII, Fig. 6, 1840. 



Unio globatus Lea. Jour. Phila. Acad. Nat. Sci., 

 2d Series, Vol. VIII, p. 5, PI. I, Fig. 1, 1874. 



Unio subglobatus Lea. Jour. Phila. Acad. Nat. Sci., 

 2d series, Vol. VIII, p. 7, PI. I, Fig. 3, 1874. 

 Specimens have been studied from the following Arkansas 

 localities: St. Francis river, Wittsburg; Ouachita river, 

 Malvern. The geographical range of the species is from 

 western New York to Texas, north to Kansas and Minnesota. 

 The species is very abundant in the Mississippi river, at 

 Moline, Illinois; in the Cumberland, at Nashville, Tennessee, 

 in the Alabama, at Selma, and is a common form in the larger 

 rivers west of the Mississippi. This shell is peculiar, though 

 it shares this feature with several other forms, in occurring 

 only in large streams. It is a mud-loving form and com- 

 monly abounds in muddy localities, where it occurs at all. 

 The synonymy indicated above is illustrated by specimens in 

 the cabinet of the writer and identified by Dr. Lea. Some 

 of them are from the original localities of the various 

 types. 



Unio elegans Lea. 



Trans. Am. Philos. Soc, Vol. IV, p. 83, PI. IX, 

 Fig. 13, 1830-1. Described from the Ohio river. 



Conchologia Iconica, Reeve, Unio, Plate LXXIV, 

 Fig. 380, 1868. 



