82 RAFINESQUE’S 
Var. 1. Viridis. Green outside. 
Var. 2. Fuscata. Brown outside. 
Var. 3. Zonalis. With green and brown zones. 
River Kentucky and Green, the largest and finest sp. of the 
West, reaching 5 and 6 inches, hinge almost without any visible 
fold. ; 
113 Sp. Anodonta digonota. (Lastena digonota, 1826.) Shell 
thin, oval swelled, back straight, obliqual, with two angles, one 
before and one behind, similar to small wings, sloping behind, with 
a flexuose edge; outside laminated, pale, olivaceous, inside bluish 
white, iridescent. Length 5-8, diameter 3-8, axis 1-4 of the 
breadth. 
From Lake Erie, two inches, hinge inside, with a flexuose fold, 
separated from the straight back. Perhaps a peculiar S. G. 
Flexiplis. 
I have besides, another doubtful Anodonta ; A. rufa, probably a 
var. of A. ohiensis, sp. 58. 
VY. Genus or tribe, CYCLAS. 
I have no new sp. of Cyclas; but I am enabled to present a bean- 
tiful new genus of this tribe, which forms the passage between Unio 
-and Cyclas. I call it Diplasma, meaning double lamellar teeth. 
The specimen before me, was not collected by myself; it belongs to 
the cabinet of shells of Mr. Hembel, of this city, who has had the 
goodness to lend it to me. It is labelled Unio, and is supposed to 
come from the river Tennessee, which I am inclined to doubt, because 
I have in my cabinet, a specimen nearly alike, from the river Ganges, 
collected by Dr. Burroughs, and because the G. Diplasma appears 
to be Asiatic. I therefore suspect that this species of Mr. Hembel, 
is also from Hindostan, and shall therefore include it in the 
following 
APPENDIX. 
On eight Asiatic bivalve fluviatile shells. 
These shells were all collected in the rivers of Hindostan, by Dr. 
Burroughs of this city. They appear very different from our North 
American shells, forming even often peculiar genera. They are 3 
sp. of Diplasma, 1 sp. Loncosilla, 2 sp. Lampsilis, and 1 
Obliquaria. 
