146 
VENERICARDIA scalaris. 
TAR. CCCCXC .—Jig. S. 
Spec. Char. Orbicular, subtriangular, depressed ; 
longitudinal sulci about 20, linear ; concentri- 
cally striated, hinge teeth long and thin. 
•The ribs (if they can be so called) are very flat and 
close together, they are so regularly crenated by the 
concentric striae as strongly to resemble a rope ladder ; 
the rather triangular form and general flatness at once 
distinguish this from both the preceding, in whatever 
state of preservation it may be met with. They all have 
toothed edges, but the number of teeth in this is greater 
than in either of the others. 
We are indebted to the Rev. G. R. Readies for the 
use of a series of specimens, consisting of above 100, by 
which these three shells were proved to be distinct spe- 
cies ; they are all of them liable to lose their external 
surfaces by decay ; but even when thus rendered imper- 
fect, the characters above given will be found to distin- 
guish them. They are equally abundant in the Suffolk 
and Norfolk Crag. 
