| Ferruginous Sand Formation. — ~ 293 
ted. Mostly found attached, and varies from one to three inches. in 
length. Same as No. 1 of this Synopsis. Common in New Jersey. 
P. pelagica. (S. G. M.) Pl. V, fig. 2. Subovate, convex, with 
twenty five or thirty narrow elevated ribs. An unattached shell. 
Found with the preceding. Resembles P. duplicata, (Sewer an 
oolitic fossil. 
PECTEN. 
P. craticula. (S. G. M.) Shell suborbicular, unequal, with about 
ten large, elevated, convex, longitudinally sulcated ribs, and a much 
smaller one interposed between each pair. New Jersey. Very rare. 
P. anatipes. (S. G. M.). Pl. V, fig. 4. With four or five broad 
convex ribs, longitudinally striated; at the sides large strie replace 
the ribs. Rarely more than half an inch in diameter. From the 
overlying limestone of Claiborne, Alabama. ; 
P: perplanus. (S. G. M.) Pl. V, fig. 5. Depressed, with about 
twenty simple coste, transversely striated. Diameter less than an 
inch. Found with the preceding species. 
P. venustus. (S. G. M.) PI. V, fig. 7. Shell thin, depressed, 
about half an inch in diameter, with fifteen or twenty double coste ; 
those on the lower valve delicately beaded. From New Jersey. — vies 
GRYPHHA. 
G. plicatella. (S. G. M.) PI. IX, fig.4. Am 
from the overlying limestone of Alabama, I defer Pein? notice of 
it in the hope of obtaining larger specimens. 
OSTREA. 
“Th addition to the O. falcata, so common in New Jersey, I am 
‘now able to give the characters of the three following species, all from 
the same beds : 
~ 0. plumosa. (S. G. M.) Ovato-triangular ; lower valve convex, 
crenated near the hinge; dorsum marked with delicate strie, radia- 
ting with fasciculi from the beak to the margin. 
0. panda. (S. G. M.) Same as species No. 2 of this Synopsis, 
where it is referred; with a question, to O. Cristagalli of Europe. 
(Vide Vol. xviii, pl. 3, fig. 22.) 
O. urticosa. (S. G. M.) Discoidal, thin, with numerous spinous cos- 
te; many individuals usually adhering together. From New Jersey. - 
ANOMIA. 
A. argentaria. (S. G. M.) Pl. V, fig. 10. Thin, round, with 
humerous concentric striz. 
