I go • Tlic American Geologist. March, i89s 
A Revision of the Piierco Fauna. By Wi D. Matthew. Bulletin 
Amcr. Mus. Natural History, vol. IX, Art. XXII, p. 259; New York, Nov. 
16th, i8g7. 
This article is the outcome of a careful study of the original material 
on which the late Prof. E. D. Cope based his description of the Puerco 
fauna. To this material has been added the collection of the Museum 
expeditions of 1892 and 1896 under the guidance of Dr. J. L. Wortman, 
so that the author has had exceptional opportunities to obtain a 
thorough knowledge of this primitive fauna of the placental mammals, 
Being the starting point in America so far as is known of so many recent 
orders of mammals this fauna, nothwithstanding the fragmentary con- 
dition of most of the material, is of the greatest interest. In dealing 
with it, Prof. Cope had to depend chiefly on jaws and teeth, and, even 
with the new material gathered by the Museum expeditions, only for a 
few forms can the skeletal characters be described. 
Dr. Wortman has described the stratigraphy of the beds and written 
a paper on the Edentata. Hie work of Dr. W. D. Matthew has con- 
sisted in a rearrangement of the species and reduction of their number. 
This removal of unsound species and readjustment of tne remainder is a 
most useful work, as giving a better basis for generalizations as to the 
bearing of this fauna on later Eocene and other Tertiary mammals. 
One important result of late studies and of this review is the discov- 
ery that the Puerco group really contains two faunas, contained in three 
fossiliferous layers, to the two lower of which the name Puerco is now 
confined, the upper being designated the Torrejon fauna. The com- 
bined faunas contain the following element: 
"i. The Mesozoic group of Multituberculates culminates in the 
Puerco and dies out in the Torrejon, true rodents coming in to take 
its place. 
"2. The main body of the fauna is composed of the primitive types 
from which sprang the ungulates on the one hand, and the .later creo- 
donts and carnivores on the other. In the Puerco these two divisions 
are hardly distinguishable; in the Torrejon they are clearly separable, 
although still closely allied, and the subdivisions of each group are fore- 
shadowed. But it must not be supposed that we have here the direct 
ancestors of all the later types; on the contrary, there are comparatively 
few forms, even in the Wasatch, that are descended from known basal 
Eocene species, and these are not the persistent t3'pes. It is clear that a 
large addition to the fauna must be made before we will come across the 
direct ancestors of most, of the modern Ungulata. The basal Eocene 
carnivores and ungulates were evolving into types corresponding to 
the modern differentiation, but to a great extent analogous only, and 
not ancestral. 
"For such primitive carnivores the term Creotfoiita is universally used. 
For the corresponding group of primitive ungulates the term Condyl- 
arthra will here be used, making it nearly etpiivalent to the hypotheti- 
cal Protungulata. 
