Review of Recent Geological Literature. 191 
•'3. A few more specialized lines may be separated from 
tliis main jjjroup. The Edentata are already well advanced in their 
differentiation. The Aniblypoda and Rodentia are just beginning, but 
clearly recognizable. A fourth type is allied to the Primates.'^ 
Two tables are given — one to exhibit the relation of the Pucrco and 
Torrejon faunas to the later Tertiary faunas. This shows "the diflfer- 
ence between the Puerco and Torrejon faunas to be mainly in the pov- 
erty of the former in families. This is not due to any scarcity of speci- 
mens or species; it points to a large immigration at the beginning of the 
Torrejon. Another considerable immigration must have taken place 
before the beginning of the Wasatch." 
The second table shows the families and species of the animals of the 
Puerco and Torrejon and the number of examples of each species ex- 
amined, in some cases over one hundred. Thirty-one species are reck- 
oned to the Puerco and forty-four to the Torrejon. Most of these 
species were originally described by Cope, four are ascribed to Osborn 
and Earle, and one to Wortman; two new species are described by Dt. 
Matthew, and another distinguished but not described. 
There are several suggestive discussions of genera and families, e:^pec- 
ially the ? Rodentia (p. 265) Triisodontido' (p. 277) Ctenodon (p. 291) Con- 
dytartJira (p. 293 and 321) AnisoncJiincv (p. 297) Phenacodontidcp (p. 299) 
F.uprotogonia (jj. 305) Mioclcenidce (p. 311), also a note on the foot struc- 
ture of the basal Eocene mammal, on p. 320. 
This article, with its full description of the archaic placentals of the 
Puerco and Torrejon faunas, accompanied, as it is, by cuts showing the 
dentition of most of them, and a full synonymy of the species, is a valu- 
able addition to the history of the development of the Mamm-ilia, and 
a convenient compendium for the student of these vertebrates. 
G, F. M. 
Geology of Massanutten Mountain in Virginia. B\ Arthik Coe 
Spencer. (Pamphlet, pp. 54, 3 plates and map Washington, 1897.) 
Among the dissertations that have recently been issued there are 
none of greater interest than that on the geology of Massanutten moun- 
tain by Arthur Coe Spencer, of the Johns Hopkins University. It deals 
with a problem that is ordinarily much too large for the thesis required 
as the final outcome of graduate work in the university. But the treat- 
ment is as full and admirable as the subject matter is interesting and 
in.structive. The area treated of is eight miles wide by forty-five miles 
long, lying between two parallel branches of the Shenandoah river. 
After a general description of the main topographic features of the 
surrounding region, the stratigraphy, Hthological characters, striJcture 
and local relief are considered. The principal effort is placed on the 
geological history of the region as elucidated by Massanutten. The 
conclusions are briefly summarized as follows: (i) After the deposition 
of the Cambro-Silurian limestone a land area was elevated opposite the 
region studied, with its seaward boundary in the vicinity of the present 
P)1ue ridge; (2) subsequent to this early revolution there were many 
