818 
APPENDIX. 
divaricata , and both, in their markings, resemble N. cobboldii of the English Miocene. Mactra 
Diegoana is nearly related to the Oregon M. albaria. 
The Eocene period is unequivocally represented by the beautifully perfect shells from the 
Canada de las Uvas, which, though not found in situ, are evidently derived from strata occur¬ 
ring on the Pacific slope of the Sierra Nevada. This is very remarkable, inasmuch as three 
species correspond with forms of Claiborne, Alabama, and seem to indicate a connexion of the 
Atlantic and Pacific oceans during the Eocene period. The vast distance between the two lo¬ 
calities will account for the general distinction of species, and it was, indeed, an unexpected 
result to find any identical. If I had imagined any eastern species to occur in California, it 
would have been the very one which does occur, and, apparently, in abundance, that “ finger¬ 
post” of the Eocene, Cardita planicosta, a fossil of the Paris basin, and also abundant in Mary¬ 
land, Virginia, and Alabama. This species originated and perished in the Eocene period, and 
is so widely distributed that it may be regarded as the most characteristic fossil of its era. As 
the boulder from which these shells were derived was quite small, and yet furnished thirteen 
species, when it shall be investigated in situ, doubtless a great many other forms will be ob¬ 
tained, and very likely some with which we are already familiar in eastern localities. Although 
the rock is a very hard sandstone, the shells may be exposed in great perfection by careful 
management, and we look forward with great interest to their further development, and to the 
discovery of the rock in situ. 
Respectfully, yours, &c., 
T. A. CONRAD. 
Wm. P. Blake, Geologist of the United States 
Pacific Railroad Survey in California. 
CATALOGUE. 
I. EOCENE. 
Name. 
Locality. 
Cardium linteum, (nova species.) Con_._...... 
Canada de las Uvas_.... 
Dosiniaalta, (nov. sp.) Con_..._ 
_.do.. 
Meretrix Uvasana, (nov. sp.) Con_,_ 
_do... 
-Californiana, (nov. sp.)Con..._,_____ 
Crassatella Uvasana, (nov. sp.) Con_,_,_ 
-alta, Con __ 
do __ _ 
Mytilus humerus, (nov. sp.) Con.___ 
Cardita planicosta_ 
Natica cetites. Con___ 
.do...... 
-gibbosa. Lea__..._ 
-alveata_ 
_do___ 
Turritfilla TTvasana (nov Pp ) Con 
Volutatitkes Californiana, (nov. sp.) Con_ __ 
.do... 
Busycon ? Blakei, (nov. sp.) Con. . __ __ _ _ 
Clavatula Californica, (nov. sp.) Con_,___ .... _..._..... 
