260 Mr. Barnes on the Genera Unio and Alasmedonta. 
—1.3 Length 1.2—2.3 Breadth 2.1—3,7 inches. 
Shell ee elongated, sub-pentangular, moderately 
shaped, longitudinally furrowed, fuscous with submembra- 
naceous strie; anterior dorsal margin straight and sub- 
truncate; basal margin rounded; epidermis greenish yellow, 
with broad dark green rays; surface glabrous. Cardinal 
teeth slightly striated, nearly smooth; posterior cicatrix 
eep and striated; naker very white, iridescen 
Variety (a) obscurely rayed, more SOBVEE, compressed on 
the base, and gaping behind. 
Inhabits Lake Champlain. 
My Collection. 
Beas RKS.—This is a beautiful species. It cannot be 
confounded with any of the varieties of the Cariosus or Ra- 
diatus, on account of the primary teeth, which are entirely 
different. We have so many specimens of this shell, and they 
are all so perfectly Sean etenats and so much alike, that 
there can be no doubtof its being entitled to a distinct appel- 
lation. In several of the specimens, the epidermis is worn 
off, exhibiting a fysh-aalgamd substance beneath. 
12. UNIO ALATUS. —Shell ovately triangular ; hinge 
margin elevated into a large wing ; valves grow- 
ing together on the back of the nti inside 
purple. 
Unio Alatus. Mr. “Saye 
Unio Alata. M. Lama 
American Conchology, Hate 4, fig. 2. 
Inhabits Fox Eeier. Mr. a 
Wisconsan, Capt. Douglas 
Cabinets of the Lyceum id Dr. Mite hill. 
We have every size of this shell from one inch to six 
nches and nine tenths broad. A full grown specimen 
measures as follows, viz. 
Diam. 2.0 Length 4 Breadth. 6. 
A = - = very splondid specimen measures 
D16 L40 B6 
