76 CONTRIBUTIONS 
to our coast, the transversa and ponderosa of Say. These 
are from the Tertiary of North Carolina, Virginia and 
Maryland. 
GENUS PECTUNCULUS. Lamarck. 
P. Broderipii. Plate 5. Fig. 53. 
Description. Shell rather oblique, inflated, inequilateral, 
nearly straight at dorsal margin, with delicate longitudinal 
linear ribs, cut by very minute transverse strie; beaks 
rather elevated ; hinge teeth arched and very diminutive 
in the centre; cicatrices slightly raised ; cavity of the 
shell deep; marginal teeth pointed, small and well defined. 
Diam. .9, Length 1.3, Breadth 1.4, of an inch. 
Observations. This species is, perhaps, most remarka- 
able for its small and beautifully pointed marginal teeth, 
and the straight line of the dorsal margin. The longitu- 
dinal linear ribs, which diverge from the point of the beak 
and extend to the margin, are beautifully cut by the fine 
concentric strize, which interrupt them. This can only 
be perceived in specimens which are in the best state of 
preservation. In young specimens, the obliquity does not 
always exist, and the shell is then equilateral. In perfect 
specimens, with the assistance of the microscope, the dorsal 
teeth will be seen to be transversely striate. 
In placing the name of so distinguished a conchologist as 
_ that of Mr. Broderip to this species, I have great pleasure. 
