4 
APPENDIX. 
A. brevij'ronx, pi. 1 , fig. 15. Shell snbrhomboidal, umbonal slope 
inflated, very oblique, rounded, much curved on the umbo which is broad 
and the summit obtuse ; cardinal line shorty posterior margin very oblique, 
slightly curved; anterior side very short, obtusely rounded; hinge line 
slightly sinuous, sculpture very fine, almost obsolete, cancellated lines 
punctate at the intersection. 
Of this extremely thin shell I obtained 3 valves, showing the hinge in 
perfection. It is widely distinct from JY. Eufalemis , Gabb, which is found 
associated with it at Snow Hill. 
In the American Journal of Conehology it is stated that Area hetero- 
donta is a species of this genus, when I meant exactly the reverse — the 
word not having been omitted by the printer. 
BARB ATI A. (dray. 
submenus blag] arc a. Conrad. 
Shell, with a straight hinge margin terminating in an angle, narrow car- 
dinal area, having minute close angnlated lines ; cardinal teeth very 
oblique without angles towards the interior margin ; short;, anterior series 
with one or two teeth comparatively large, slightly angulated in the 
middle and very oblique. 
B. Carolinensis, pi. 1, fig. 11. Shell trapezoidal, ventricose, very 
inequilateral, umbonal slope acutely rounded above, undefined below, 
anterior margin truncated ; posterior end emarginate below the hinge 
extremity ; disk with numerous prominent unequal closely-arranged, very 
narrow ribs, crenulated and with a few intermediate lines. 
SUBGENUS POLYNEMA. Conrad. 
Shell with the hinge line slightly descending, the teeth on both sides 
very oblique, those of the posterior side elongated, striated, the series 
suddenly terminating in a few short teeth ; cardinal margin straight, 
angulated at the ends ; cardinal area extremely narrow with two profound 
lines angulated under the beaks. 
B. lintea , pi. 1, fig. 12. Shell trapezoidal, subulated posteriorly ; 
umbonal slope inflated, rounded ; disk cancellated with very numerous 
close lines, the radii most prominent, acute. 
This is a thin, rare shell allied in subgeneric characters to Area Kd- 
wardsli and A. distans, Reshapes. 
