6 Trans. Acad. Sci. of St. Louis. 



fine specimens of this form. One of these measures in length 

 175 mm., in height 105 mm., in breadth 51 mm. 



Unio anodontoides Lea. 



Trans.Am.Philos.Soc.,Vol.IV, Pl.VIII,Fig.ll,1830. 

 Unio teres Rafinesque, vide Conrad's Monograph, PI. 

 XXVIII. 



St. Francis river, at Wittsburg and Madison; Saline river, 

 at Benton. 



This species is very widely distributed over the United 

 States from western New York to Alabama and Texas, rang- 

 ing north to Indiana, Minnesota, and Kansas. It is well 

 marked and is distinct from Unio luteolus Lamarck, with which 

 it is often confounded. The St. Francis specimens are very 

 large and fine. 



Conrad's figure of Unio teres is said by him to be based 

 upon a specimen in Mr. Poulson's cabinet, which was said to 

 have been labeled by Rafinesque himself, who collected it "in 

 the west." 



Unio arkansasensis Lea. 



Jour. Phila. Acad. Nat. Sci., 2d series. Vol. V, PI. 

 XXX, Fig. 275. 

 The only Arkansas specimens seen came from the Saline 

 river, near Benton. One is quite imperfect while the other, of 

 the two, is a good representative of the female of the species. 

 The original specimens came from *' Hot Springs " and pre- 

 sumably from the Ouachita river. 



Unio breviculus Call. 



Plate XVII. 



Proc. U. S. Nat. Mus., Vol. 10, p. 499, Plate XXVIII, 

 1887. 



White river, Carroll county; Little Red river, Clinton, 



Van Buren county, Arkansas. Jack's Fork of Current 



river, Missouri ; Big Creek, tributary to Jack's Fork, 



Texas county, Missouri. 



Shell smooth, ovate elliptical, inequilateral, subinflated, 



biangular posteriorly, circularly rounded before, somewhat 



