108 



in many specimens a little contracted hear the pos- 

 terior termination; within bluish-white, pelaceous. 



SYNONYMES. 



U. heros, Say, Disseminator of Useful Knowledge, vol. ii., p. 



291, Sept. 1829. American Conch, No. vii. pi. xvi. 

 U. xjndulatus, Say, (not Barnes,) American Conch, pi. 16. 

 U. multiplicatus, Lea, Trans. Amer. Philos. Soc, (new series) 



vol. iv. p. 70, pi. iv., 1831. 

 Cab. A. JV. 8., No. 



OBSERVATIONS. 



Say remarks of this species, that "it resembles the 

 plicatns, nob., but on comparison it will be observed 

 to differ essentially from that common species." It 

 is, however, more nearly related to the costatus of 

 Rafinesque, with which Say at one time confounded 

 it, although he had previously published it under the 

 name of heros. In his synonomy of the western 

 species of Unio and Alasmodonta, he very properly 

 reclaims the species. It may readily be distinguished 

 from the costatus by the small letter-shaped undula- 

 tions on the umbo, darker epidermis, and by other 

 less obvious characters. Say informs us that it in- 

 habits the Wabash river and tributaries. I am in- 

 debted to Mrs. Say for the use of the beautiful and 

 very accurate plate, originally published in the 

 American Conchology. 



Deshayes considers this species identical with the 

 undulatus of Barnes, and refers it to IT. peruviana, 

 Lam.* 



* Anim. sans Vert., vol. vi. p. 533. 



