— se 
Eocene Fossils of the United States. 395 
Arr. VII.— Observations on the Eocene formation of the United 
States, with descriptions of species of Shells occurring in tt ; 
by T. A. Conrap,—(with plates. ) ; 
(No. 2. Continued from page 221.) 
; CRASSATELLA. 
Tis genus is not recognized with certainty in deposits older 
than those of the Cretaceous strata, in which I discovered two 
species in New Jersey. Five occur in the American Miocene, 
but the Post-pliocené contains none, nor is there a recent species 
known to inhabit the coast of North America. Deshayes enume- 
rates twenty-four species in the tertiary formations of Europe ; 
fourteen of which are in the Paris Eocene. 
Crassarenia Auta. Suborbicular, thick and ponderous, slight- 
ly ventricose above, somewhat compressed inferiorly ; surface 
with coarse lines of growth, beaks submedial, separated ; umbo 
transversely sulcated towards the sumifit; dorsal margins equal- 
ly and profoundly oblique ; posterior margin direct, truncated ; 
posterior dorsal area profoundly depressed ; lunule large, elliptical, 
very profound, deepest at the anterior extremity ; cardinal plate 
profoundly dilated, the fosset extending not more than half the 
width of the hinge plate ; in the left valve, behind the large tooth 
and beneath the fosset, is a deep triangular cavity ; inner margin 
erenulated. (Plate III, fig. 1.) 
C. alta, Con.; Foss. Shells of ‘Tert. Form., p. 31, plate vil. 
Desh., Lam. ; Anim. sans Vert., vol. vi, p. 116. 
Claiborne, Alabama. 
This large species is allied to C. tumida, Lam., an Eocene fos- 
sil of the Paris basin. It is proportionally more elevated, and 
Deshayes remarks that the hinge is less strongly articulated. It 
is common at Claiborne, and rarely occurs with connected valves. 
I found casts of this shell near Long Branch, N. J., where a bed 
of infusorial earth of Eocene date also occurs. 
CrassaTeLta prorexTa. Somewhat elliptical, elongated ; lower 
half of the valves sulcated; umbo and beak with fine, closely 
arranged regular sulci; valves somewhat contracted anteriorly, 
~ tumid on the posterior part of the umbo ; umbonial slope prom- 
inently folded; posterior slope rugose ; ‘posterior extremity ob- 
liquely truncated ; umbo carinated on the umbonial slope ; basal 
