14 INTRODUCTION. 
sonian Institution, visited the locality in 1850, and brought home a valuable addi- 
tional collection of mammalian and chelonian fossils. 
From a variety of favorable circumstances, but especially through important aid 
from the Smithsonian Institution, and Dr. D. D. Owen, I have been enabled per- 
sonally to inspect all the animal remains brought from Nebraska, of which I have 
had any intimation. In commencing, then, with a description of the Eocene Fauna 
of Nebraska, the following collections were submitted to investigation. 
1. The original fragment of a maxillary bone described by Dr. Prout, with the 
addition of several other important specimens. These were kindly loaned by Dr. 
Hiram A. Prout, of St. Louis. 
2. A collection which accompanied the former, belonging to, and obligingly 
loaned by Prof. O’Loghland, of St. Louis. 
3. Specimens presented by Alexander Culbertson, Esq., through Joseph Cul- 
bertson, Esq., to the Academy of Natural Sciences, of Philadelphia. 
4. The collection made by Dr. John Evans, at the instigation of Dr. D. D. 
Owen, for the United States Government, and now belonging to the Smithsonian 
Tnstitution. 
5. A collection procured, as above mentioned, by Mr. Thaddeus A. Culbertson, 
for the Smithsonian Institution. Very important aid in making this collection was 
rendered by Mr. Alexander Culbertson. 
6. A small but very excellent collection made by Captain Stewart Van Vliet, of 
the United States Army, and by him presented to the Smithsonian Institution. 
These specimens, though last received, were actually among the first collected, 
having been procured by him when on a journey from Fort Pierre to Fort Lara- 
mie, in company with Mr. Alexander Culbertson, who, on the same occasion, ob- 
tained the specimens first described by me. 
Most of the specimens when received, were partially enveloped by, or had 
attached to them a hard, silicio-caleareous clay, of a dirty cream color; and the 
same material fills the cavities of the skulls and the interior of the turtle shells. 
This matrix, according to Dr. D. D, Owen, has the following composition :—" 
Water of absorption . ; 0 : é : : . HO 2.50 
Flesh-colored silicious earth, insoluble in chlorohydric acid. . 33.00 
Lime : E 5 : ‘ : ; D ; ‘ . CaO 30.90 
Carbonic acid . ‘ , F F : : : : . CO, 19.00 
Sesquioxide of iron . : : : . : : : 5) LOGE) 2.00 
Alumina . 2 ; 5 : : 3 ; ; 4 ~ ALLO: 1.00 - 
Manganese : : : : ; : ‘ . ; - MnO 1.00 
Magnesia 3 ; : : , : : 5 d . MgO 1.00 
Phosphoric acid ; : : : : : : 3 : 1.80 
Chlorine . : : : : F : : ‘ 5 AOI 0.44 
Potash. 5 Z : : ‘ , . : ‘ kK 4.08 
Soda and loss. é : ; : : : : ‘ . NaO 3.28 
100.00 
* Rep. of a Geolog. Sury. ete., p. 606. 
