Eocene Fossils of the United States. 401 
found at Claiborne, Alabama, but is so rare that I have seen but 
one valve. Lamarck describes but one recent species, an inhab- 
itant of the Indian Ocean. ; 
Corgis unpata. Ovate, ventricose, with about twelve concen- 
tric ribs or undulations, very strongly prominent, acute, remote on 
the umbo, lamelliform towards the apex, but thick, less prominent 
- and approximate towards the middle of the valve ; on the infe- 
rior half of the valve are irregular concentric compressed lines ; 
disk with radiating lines, obsolete on the middle of the inferior 
half of the valve, profound on the sides, crenulated on the an- 
terior side; posterior side with distant prominent lamelle, five 
or six in number; beaks medial; inner margin crenulated. 
(Plate IV, fig. 11.) . 
Corbis undata, Con.; Foss. Shells of Tert. Form., p. 40. 
C. distans, Con. ; ib. (Immature shell.) 
Claiborne, Alabama. Z 
A beautiful and very rare species. Immature shells have acute 
prominent remote ribs, covering the whole disk, and are compar- 
atively less ventricose than mature specimens. ; 
Corgis Lameiiosa. Elliptical, compressed, with distant ele- 
vated lamelliform ribs, and fine radiating strie ; ribs towards the 
base less remote and more robust; on the posterior slope the 
lamine are more profoundly elevated. (Plate IV, fig. 16.) 
Corbis lamellosa, Lam.; An. sans Vert. Chemnitz ; Conch., 
vol. vi, tab. xiii, figs. 137, 138. Encyc. Meth. plate eclxxxvi, 
figs. 2,a,b,c. Desh. ; Coq. Foss., t. i, plate xiv, figs. 1, 2, 3. 
Claiborne, Alabama. 
The extreme scarcity of this shell at Claiborne is remarkable, 
as it is very abundant in the Paris Eocene. It varies little from 
the Paris specimens, the principal difference being in the thicker 
and more approximate ribs towards the base. 
Lucina. 
The genus Lucina of Bruguiere is very numerous in fossil and 
recent species. Deshayes enumerates as many as fifty nine ter- 
tiary species, thirty one of which are in the Paris Eocene. ‘The 
number, however, will be somewhat restricted by separating the 
group termed Loripes by Poli. In Europe the genus is supposed 
to occur as low as the Great Oolite. 'The Eocene of this country 
contains seven known species; the Miocene twelve, of which 
