22 eamnksque's 



[From the American Monthly Magazine and Critical EeTiew, Vol. Ill, 



page 354, New York, 1818.] 

 Discoveries in Natural History, made during a Journey through 

 the Western Region of the United States, by Constantine 

 Samuel Safinesque,- Mq. Addressed to Samuel L. Mitchill, 

 President, aud the other Members of the Lyceum of Natural 

 History, in a letter dated at Louisville, Falls of Ohio, 20th 

 July, 1818. 

 [355] 



4. Conchology or the Shells. I trust I have discoTered likewise 



the greatest proportion of the shells of the Ohio, having already 

 collected and described over 30 species, the whole of which appear 

 to be new; they consist of 24 bivalve and 8 univalve shells. It is 

 strikingly singular that those shells belong only to 3 genera, that the 

 24 species of bivalve belong all to a single natural genus ; and that 

 those genera are all different from European fluviatile genera, which 

 I have ascertained beyond a doubt by the shells and animals thereof. 

 I shall add the characters of these new genera. 



I. PoTAMiLUS.* Bivalve- Shell equivalve unequalateral, com- 

 monly transverse, rugose transversely, sloping posteriorly, shape 

 variable, margin thickened, two muscular impressions, an epidermis 

 surrounding the margin by a membranaceous brim, connective 

 oblong convex membranaceous. Ligament with two teeth on one 

 side, and a deep furrow on the other, between two carina in the left 

 shell, while the right shell has two unequal teeth, and two unequal 

 carinas. 



Animal with a mantle open and bilobe, branchias as a second 

 interior mantle, body compressed tough, two openings or siphons 

 anterior on each side, not tubular, one foot on each side commonly 

 bilamellose, next to the openings. 



1. Sub-genus. -Shell transverse, not truncated, thick and without 

 knobs; 1. Potamilu's latissimus ; 2. P. violacinus ; 3. P. niger ; 

 4. P.fasoiolaris; 5. P.phaiedrus; 6. P. ellipticus; t. P. zona- 

 lis ; 8. P. obliquatus. 



2. Sub-genus. • Shell transverse, truncated posteriorly, thick and 

 without knobs. 9. Potam. retusus ; 10. P. truncatus; U. P. 

 triqueter. 



5. Sub-genu.«. Shell transverse, thin, not truncated. 12. P. 

 alatus; 18. P. leptodon; 14. P. fragilis ; 15. P. nervosusj 16. P. 

 fasciatus ; 17. P. auratus. 



* If I remember right, this genus ia also found in the Hudson river, whore 3 or 4 Bnecies are to 

 be seen, which huve been mistallea for Jti/a or CardCum. "iioi-i™ 



