52 The Ainerican Geologist. juiy, isoi 
Theory of igneous rocks and volcahoes (1858); On some points in cliem- 
ical geology (1859); The chemistry of meta morphic rocks (1863); Tlie 
chemistry of the primeval earth (1867); The origin of mountains (1861); 
The probable seat of volcanic action (1869); On some points in dynami- 
cal geology (1858); On limestones, dolomites and gypsums (1858-66); The 
chemistry ox natural waters; On petroleum, asphalt, pyroschists and 
coal; On granites and granitic vein-stones (1871-73); The origin of 
matalliferous deposits : The geognosy of the Appalachians and the origin 
of crystalline rocks ; The geology of the Alps; History of the names 
Cambrian and Silurian in geology; Theory of chemical changes and 
equivalent volumes (1853); The constitution and equivalent volume of 
mineral species (1853-63); Thoughts on solution and the chemical 
process (1854); On the objects and method of mineralogy (1867); Theory 
of types in chemistry (1848-1861). The volume is dedicated to James 
Hall. 
Such topics, covering nearly the whole field of chemical geology, are 
discussed in Dr. Hunfs well-known style — a style which for breadth of 
learning and comprehensive scope, no less than for its penetrating, ap- 
prehension of the occult relations of chemical and dynamic forces, 
has caused his writings to be held among our highest speculative au- 
thorities on these subjects. The geological literature of the latter half 
of the nineteenth century will always bear a profound impress derived 
from the labors of Dr. Hunt. 
The Fossil Insects of North America, with notes on some European 
species. By Samuel H. Scudder. Vol. I. The Pretertiary Insects, 
pp. X, 455, with 35 plates. Vol. II. The Tertiary Insects, pp. 734, with 
map of the Tertiary lake basin at Florissant, Colorado, and 28 plates. 
(New York : Macmillan & Co. 1890.) A series of eighteen essays, origi- 
nally published in the Memoirs of the Boston Society of Natural History 
from 1866 to 1890, forms the first volume of this work, which is limited 
to one hundred copies. Bibliographic references and an index are added. 
The longest paper, which bears date of 1879, comprises 111 pages and 
treats of Paleozoic cockroaches, both North American and European ; 
and another paper of 46 pages, reviews the Mesozoic cockroaches. 
Winged insects are known to have existed during the Silurian period, 
but up to the close of Paleozoic time they were represented only by a 
generalized form, which had the front wings as well as the hind wings 
membranous. In the Mesozoic era, according to Mr. Scuddor, '• a great 
differentiation took place, and before its middle all of the orders 
were fully developed in all their essential features as they exist to-day." 
The Second of these volumes was published last year as number XIII 
of the final reports of the U. S. Geological Survey of the Territories, 
which was conducted by the late Dr. F. V. Hayden. About a third of 
this volume, comprising the Arachnida, most of the Neuroptera, and the 
Orthoptera, was written during the years 1881 to 1884 ; but the descrip- 
tions of the Coleoptera, Diptera, Hymenoptera, and Hemiptera, the last 
being the most extensive group, were written during the two years im- 
mediately preceding publication. For the lower orders.' all the Ter- 
