CHAPTER 111. 
PALEONTOLOGY. 
I have placed in this Chapter descriptions and notes relating to the fossils that I met with in 
my travels in the Far West. Several of them are new, others are European species not previ- 
ously pointed out in North America, and some are American species already well known, whose 
geographical distribution is extended by the new localities in whichl found them. The greater part of these 
fossils have been submitted to Messieurs Agassiz, de Verneuil , de Koninck, d’Archiac, Jules Haime, 
Pictet and Deshayes, who were kind enough to aid me in their determination; I thank them most 
cordially for their assistance, and I have endeavoured in the following pages to profit by the coun- 
sels with which they have honored me. 
N. B. — All the specimens are represented of the natural size, exactly as they are; and 1 
have not attempted to restore the imperfect portions , as has been done by many paleontologists , 
from a fear of making too fantastic additions to nature, which are very difficult to avoid in such 
cases. 
FOSSIL OF THE TERTl.LRY ROCKS. 
OSTREA VIRGIMCA vai. C.VLIFORNICA. 
Plate V , fig. 2. 2 a. 
Descriplion. — Ostrea tesla elongala, angusta , crassa ; valva iiiferiore convexo-tectiformis, sublamellosa ; unibo- 
nibus elongatis, acuminatis; fossula cardinali valvfe iiiferioris late sed obsolete canaliculata, utroque latere raargine 
plano-convexo circumdata. 
Observaliom. — This oyster is certainly a variety of the Ostrea Yirginica Gmclin; it has the same 
characters, size, form, as well as texture. The^nly perceptible dilference that 1 find in comparing it 
with well preserved specimens of the living species, is that the sulcus for the ligament is not so deep. 
This character distinguishes it also from the Ostrea Moreleti Besh. (See: Note sur quelques fossUes rappor- 
tds par M. Morelet du Yucatan, par Deshayes, in the Bull, de la Soc. Geol. de France, deuxieme serie , 
tome X, pag. 509. Paris, 1853.), which has a very deep sulcus. 
Conrad has described under the name of 0. Heermani (See ; Journ. Acad. Nat. Sc. , Philadelphia.) a 
very irregular oyster, found in the same locality of the Colorado desert, California: but as he gives no 
drawing, I cannot decide if it is the same species. 
Locality. — The specimen, here figured, is the only one that I have ever seen; it was found 
by Captain A. W. Whipple in the Colorado desert, California; near Carrizo creek, between San 
Diego and Fort Yuma. 
The Virginian oyster, Ostrea Yirginica, is found in a fossil state in the Faluns de la Touraine, at 
Saucats near Bordeaux, at St. Paul near Dax , in the neighbourhood of Bayonne , in the Mollasse 
