;U)2 The American Geologist, DeccmbtT, lyi'i 
to local changes in conditions during the continuance of the same epoch. 
The species described in this work, represented mostly by collections 
belonging- to the National Museum, the Academy of Natural Sciences 
of Philadelphia, and Rutgers College, are comprised in the following 
classes: Brachiopoda, 1 : Lamellibranchiata, (51 : Gasteropoda, 39: and 
Crustacea, 1, this lieing a Balanus. similar to the common barnacle still 
living fm the New Jersey coast. "w. r. 
A Gi'i)l(>!jical Rccoitiioissinice in Nortlnrcxt W'fjojiiiiig. By (xEorge 
HoMANs Eldrioge. (U. S. Geological Survey, Bulletin 119, jjp. 72. with 
a geologic map and sections : Washington, 189i. Price, 10 cents.) An 
area about 150 miles square in Wyoming, with an adjoining tract 150 
miles long and 15 miles wide in Montana, is here described, special 
attention being directed to its economic resources. The district com- 
prises the Wind River and Big Horn basins, each nearly inclosed by high 
mountain ranges, and drained respectively by upper and lower parts of 
the same river. The rock formations are of Archean, Cambrian. 
Silurian, Carboniferous, Triassic, Jurassic, Cretaceous, and Eocene 
age. Archean granites, gneisses, and schists, form the chief mass of 
the Big Horn and Wind River mountains : but the southern part of the 
Big Horn range consists of Carboniferous strata. All the members of 
the Cretaceous series, as developed in the Upper Missouri region, are 
displayed on the flanks of the numerous mountain ranges. Lastly, in 
the lowlands, the Wasatch and Bridger deposits of the Eocene period 
occupy larger areas than those of the older formations in this district. 
Lignite coal seams, mostly too thin to be w^orkable, but ranging in 
thickness up to ten feet, occur in the Laramie formations : and in one 
locality the Niol)rara beds contain a lignitic layer about two feet thick. 
Petroleum springs issue in various places from the Triassic red beds 
and the Niobrara shales. Three oil wells, 100, 600, and 1,000 feet deep, 
have been sunk, and yield an abundant and steady surface flow, when 
it is jjermitted : but thej' are kept closed because of the distance from 
any market. "The natural occurrences of oil, and the success thus far 
attained in the drilled wells, warrant firm and favorable belief in the 
future (jf the Wyoming petrolevun fields." 
Building stones of excellent quality, clays well adapted for brick- 
making, beds of gypsum 5 to 30 feet thick, gold in certain conglomerates 
and sandstones on the Big Horn range, several very large hot springs 
held in high repute for their curative qualities, and the scanty agricul- 
tural lands within irrigable limits, complete the list of the natural re- 
sources of the region. Away fi-om the mountains and streams, the 
country is "a vast desert, intensely heated in summer, wind-swept in 
winter, with hardly a spear of grass for grazing." w. r. 
Elementarij Physical Geography. By Ralph S. Tarr. (Pages xxxi, 
188, with 29 plates and charts, and 267 figures in the text. Macmillau 
& Co., 1895. Price $1.10.) The present treatise, designed as a text book 
for schools, is based on the manuscript of a more advanced work, which 
is soon to be jjublished as a handloook for teachers and for reference. 
