52 Trans. Acad. Sci. of St. Louis. 



county ; the St. Francis river, at Wittsburg ; the Ouachita, at 

 Arkadelphia ; the Saline, at Benton. 



A specimen of this shell was reported on by Dr. Lea in the 

 Proceedings of the Philadelphia Academy of Natural Sciences 

 for 1860, page 51, to which was assigned the indefinite locality 

 of ** Arkansas." It was reported under the name of Unio 

 nasutus Say, a species which does not occur west of the 

 Appalachians, outside of the drainage of the Great Lakes. It 

 was peculiar in that the teeth were reversed, being single in the 

 left and double in the right valve. 



In some MS notes left by Dr. G. Troost in his copy of 

 Volume I of Observations on the Genus Unio, now in the 

 library of Dr. J. Berrien Lindsley, of Nashville, the statement 

 is made that the shell which Lea called Unio nashvillianus was 

 not originally found in the Cumberland river, but in the Har- 

 peth river, some miles further south. The original locality 

 will, therefore, be the latter river. The original specimen, 

 with Lea's name in MS is now in my possession. The writer 

 has, however, found the species in the Cumberland, at 

 Nashville. 



Unio tetralasmus Say. 



Plates XIX, XX. 



American Conchology, Plate XXIII, 1830. Described 

 from the Bayou St. John, Louisiana. This plate is copied 

 in Plate XX herein, figures 4, 5. 



Unio declivis Say. Transylvania Journal of Medicine, 

 Vol. IV, 1831, p. 527; American Conchology, Plate 

 XXXV, 1832; Conrad, Monograph of Unio, p. 45, PI. 

 XXIII, Fig. 1, 1836. Described from the Bayou 

 Teche, Louisiana. 



Unio ca7nplodo7i Say. American Conchology, 1832, PI. 

 XLII, Reeve, Conchologialconica, Vol. XVI, Unio Plate 

 LXX, Fig. 356. From near New Orleans, Louisiana. 



Uiiio geoinetricus Lea. Trans. Am. Philos. Soc, Vol. 

 V, 1832, p. 38, PI. IV, Fig. 10. Described from the 

 Bayou Teche, Louisiana. 



Unio excuUus Conrad. Monograph of Unio, 1836, 



