200 
C AUDIT A abrupta. 
TAB. LXXXI X.—Fig. 2. 
Spec. Char. Triangular,, gibbous; beaks project- 
ing near one angle; obliquely striated,, anterior 
gide longitudinally striated; five or six trans- 
verse reflected ridges along the front. 
Some of the oblique striae meet the longitudinal upon the 
anterior side at an acute angle, the remainder abruptly ter- 
minate at the first transverse ridge. The anterior side is 
nearly straight, forming the shortest side of the triangle: 
the striae are curvilinear. 
From the same place and by the same favor as the last. 
The thin shelly remains cover the greater part of the spe- 
cimen. 
Not having seen the hinge of either of these, I cannot 
pronounce with certainty that I have placed them under the 
right Genus. I am desirous of seeing more specimens, 
therefore I make these public, that by thus recommending 
research, we may learn whether these are mere varieties, 
and perhaps make further discoveries. There are, probably, 
many species which may agree with them in Generic cha* 
racter, and which at present want places in the system. 
