206 TRANS. OF THE ACAD. OF SCIENCE. 
rise abruptly from the smooth, even surface of the shell, leay- 
the space between them flat and smooth; beaks pro 
- terior | recurved, inclining forward, distant; lunule deep, 
s in the » markings. is is ‘‘ tenuissime strt 
_ Collected by Maj. Hawn in K. T., No. 98 of his general 
Missouri State sled from Lower Cons Meas- 
a "Hevea apse and Middle Coal Measures, 
County. 
t 
Tsocanpra ® curTa, Shumard. 
"Shell sian sub-quadrate, gibbous, proce and neigh a 
equal; cardinal margin short, gently rounded ; posterior bord 
obliquely ee gently roun rounded ad forming an obtuse 
| with the palleal border, which is slightly arcuate; bue- 
descending with _ 
of the valves and - beaks elevated above the 
nal line, strongly i 1, situated e-third the length 
of the shell from the anterior extremity. | 
The specimens in the collection are all destitute | of cota | 
The ithe os exhibits obscure concentric folds : | 
Din a 44; length, 46; thickness, 5 305 9 | 
= Gio Po. and Loc—Coal Measures, Chardon St He : | 
ond State nolan 
