396 Eocene Fossils of the United States. 
margin sinuous; inner margin finely crenulated. (Plate III, 
fig. 2.) 
C. proterta, Con. ; Foss. Shells of Tert. Form., p. 22, plate viii, 
2 
Claiborne, Alabama. 
A very abundant species, rarely found with united valves. It 
is variable in form, and very young shells have the whole disk 
sulcated; they are proportionally much shorter than adult spe- 
cimens, and of a trapezoidal outline. 
Plate IU, fig. 4, represents outlines of two varieties of the im- 
mature shell. ; 
CRASSATELLA ALZForMIs. Oblong-ovate, convex, with distinct 
lines of growth, which towards the anterior margin become reg- 
ular, prominent striz# ; umbo and beak flattened and profoundly 
sulcated; anterior margin of the umbo gibbous ; posterior side 
produced, cuneiform, obliquely truncated at the extremity ; um- 
bonial slope somewhat angulated ; lunule elliptical, profound ; in- 
ner margin finely crenulated. (Plate IIT, fig. 3.) 
_ C. aleformis, Con.; Jour. Acad. Nat. Sci., vol. vi, p. 228, 
plate x, fig. 1. 
_ Piscataway, Prince George’s Co., Maryland. : 
I found a single valve of this species in 1830 in the sandy 
marl, or mixture of siliceous sand, clay and green sand, where it 
accompanies Cardita planicosta and many other Eocene shells. 
I have since obtained two more valves, and find the outline to be 
very uniform in this species. 
CRaSSATELLA RHOMBOIDEA. Oblong, rhomboidal ; anterior mar- 
gin obliquely subtruncated at base; posterior margin obliquely 
and widely truncated, the inferior extremity rounded ; posterior 
dorsal margin not very oblique; basal margin slightly curved. 
(Plate IL, fig. 5.) 
Orangeburg, 8. C. 
This is a cast in indurated clay, presented by Dr. Wm. Blanding: : 
The outline is more perfectly rhomboidal than in any other Ameri- 
can species. Mr. Vanuxem obtained similar specimens in t 
same district of South Carolina. tee 
CRASSATELLA PALMULA. Ovato-trigonal, profoundly compressed, 
the umbo almost rectilinear ; dorsal margins very oblique, equally 
declining, the ligament margin straight; the anterior margi? 
swelling slightly ; apex nearly central; posterior extremity trul- 
cated? (Plate IV, fig. 1.) 
im 
= Ee ye ee en 
