122 Mr. Barnes on the Genera Unio and Alasmodonta.. 
side, elevated, and recurved, with the ligament passing be- 
tween them; anterior lunule long-heart-shaped, and sepa- 
rated by a slightly elevated heel ; hinge margin depressed, 
between the beaks; basal margin waved and rounded be- 
hind, compressed in the middle, angulated before; epider- 
mis horn-color, exhibiting a light yellowish green where the. 
surface is worn or rubbed, wrinkled and finely striated trans- 
versely ; surface glabrous. Cardinal teeth deeply sulcated 
and crenated; lateral teeth two in each valve! internal or 
lower one of the left valve small, but distinct and elevated, 
and both marked with fine dotted striae. Muscular impres- 
sions deep, posterior one rough. Nuker pearly white. 
Remarks—This shell, as will be seen by its dimensions, 
has a more globose form than perhaps any other Unio. It 
will stand erect on the posterior side, and in this position 
has “ang oh of a pyramidal appearance. 
y (a.) Shell less, very slightly compressed, anterior 
seay pile flattened, and the separating heel more eleva- 
No posterior lunule ; ; transverse ei ae 
hinge bent to nearly a right angle. ‘Teeth somewhat 
pressed. Naker, pink or fle sh colored ; autftt plished 
and — . 
Diam. 1:0 Length, 1°4 Breadth, 1-6 
. Dr. Mitchill’s Cabinet. 
temarks.—This shell differs in so many particulars from 
the former that we might have given it a different specific 
designation, had we not been averse to doing that in me case 
of solitary specimens. The vee lateral ‘tooth of the left 
valve ts distinct. 
a. inside. 
5. Unio Cornutus. Fig. 5. . outside. 
. Posterior slope. 
Shell sub-orbicular, divided losigieidiuatey by a regular 
row of large, distant tubercles, 
Hab. Fox yall Schoolcraft. 
j ollection. 
Diam. 1°0* Modi 1:7 ~—Breadth, 1°8 
* Excbusiye of the horns. 
