Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 5, Pt. 2

APPENDIX.
and having a few slight concentric undulations inferiorly; ligament slope very oblique, rectilinear, anterior extremity regularly rounded.
Locality. —Canada de las Uvas, with the preceding species.
6. C. ALTA, C nrad.-This species occurs in the same rock with the preceding, but only in
small fragments. It appears to have been abundant, as it likewise is at Claiborne, Alabama.
The fracture has resulted from breaking the rock, as the shell appears to have been perfect and
not water-worn.
MYTILUS, Lin.
7. M. HUMERUS, Con., P1. II, fig. 10.-Ovate, ventricose, summit acute; anterior margin rectilinear; basal margin rounded; anterior extremity less obtuse; disk with minute radiating
lines.
Locality.-Canada de las Uvas, with the preceding fossils.
CARDITA, Brug.
8. c. PLANIcOSTA, Pi. II, fig. 6.-Obliquely cordate; ribs about 22, broad and flattened,
separated by a narrow groove which becomes obsolete towards the base; ribs on the posterior
slope narrow, indistinct, and crossed by numerous profound wrinkles. Lunule small, cordate
profoundly impressed; inner margine crenate.
Locality.-Canada de las Uvas, with the preceding fossils. Venericardia planicosta Lam.
An. Sans Vert. (Desh. ed.) vol. vi., p, 381.
This common species occurs much larger, though less perfect, than the one represented. This
shell occurs abundantly in the Eocene strata of Maryland, Virginia and Alabama, and is quite
as characteristic of the American as of the European Eocene period. I discovered it in Maryland in 1829, and at that time regarded it as the first indication of the occurrence of deposits in
the United States synchronous with those of the London clay. Prof. Rogers has since named
this shell Venericardia ascia.
NATICA, Adamson.
9. N. CITITES? Con., P1. II, fig. 7.
Locality.-Canada de las Uvas, with the preeeding fossils.
N. etites., Conrad.-Foss. shells of Tert. Form. October, 1833.
10. N. GIBBOSA and SEMILUNATA, Lea. Cont. to Geol. December, 1833.-There is but one specimen
of this shell, which I refer with doubt to a Claiborne species. The outline is similar to that of
the latter, but the aperture is concealed in the rock, which prevents the necessary comparison to
determine the identity or the difference.
11. N. ALVEATA, Con., P1. It, fig. 8 and 8a.-Volutions 5, flattened above, carinated on the
angle, a few minute obsolete lines revolve on the upper side of the whorls; aperture inclining
to an obovate form; umbilicas small.
Locality..-Canada de las Uvas.
This species is remarkable for its truncated whorls, which are channelled by the carina on the
margin. There-are no analogous species in the Eocene of the Atlantic slope.
TURRITELLA, Lam.
12. T. UVASANA, Con., P1. II, fig. 12.-Subulate, whorls with the sides straight and oblique
above, rounded below, and having large revolving strip with intermediate minute lines; strie
near the suture on the upper part of the whorls finer than the prominent lines below.
41 F
321