Recent Publications, 195 
chain of the Caucasus, their age not yet being sufficiently determined. 
The Silurian is likewise divided into two parts, and the Cambrian is rep- 
resented entire. An attempt is made to separate the crystalline schists 
from the massive rocks, such as the granites, syenites, gneisses and por- 
phyries, but it is admitted by the authors that the scale of the map is 
too small to warrant a claim of exactness, and especially if it be recog- 
nized that there are numerous intergradations through the intermediary 
of the gneisses. The basic eruptives and the tuffs, breccias, and green 
schists have special petrographical symbols on the face of the map. 
The distribution of the recent volcanoes is also shown. 
The principal authors of the map promise, in addition to the "note 
explicative," to prepare special articles, giving the principles according to 
which such or such geological facts are expressed by them on the map, 
also an account of the extension of the different geological formations 
in the territory of Russia. 
RECENT PUBLICATIONS. 
I. Government and State Reports. 
Monographs of the U. S. Geol. Survey: Vol. XVII, The Flora of the 
Dakota Group, a posthumous work, by Leo Lesquereux, edited by F. H. 
Knowlton. 1891,400 pp., 66 pi. — Vol. XVIII,Gasteropoda and Cephalopoda 
of the Raritan clays and Greensand Marls of New Jersey, by R. P. 
Whitfield. 1892; 402 pp.,50 pi.— Vol. XX, Geology of the Eureka District, 
Nevada; with an atlas, by Arnold Hague. 1892; 419 pp., 8 pi., 9 fig., and 
13 atlas sheets. 
Bulletins of the U. S. Geol. Survey: No. 82, Correlation Papers— Cre- 
taceous, by Charles A. White. 1891; 273 pp., 3 pi., 7 fig. No. 83, Cor- 
relation Papers — Eocene, by W. B. Clark. 1891; 173 pp., 2 pi. No. 84, 
Correlation Papers — Neocene, by W. H. Dall and G. D. Harris. 1892; 
349 pp., 3 pi., 43 fig. No. 85, Correlation Papers— The Newark System, 
by I. C. Russell. 1892; 344 pp., 13 pi., 4 fig. No. 86. Correlation Papers— 
Archean and Algonkian, by C. R. Van Hise. 1892; 549 pp., 12 pi. No. 
90, Report of the Work Done in the Division of Chemistry and Physics, 
mainly during the fiscal year, 1890- ? 91, by F. W. Clarke. 1892; 77 pp., 
3 fig. No. 91, Record of North American Geology for 1890, by N. H. 
Darton. 1891, 88 pp. No. 92, The Compressibility of Liquids, by Carl 
Barus. 1892; 96 pp., 59 tables, 29 pi. No. 93, Some Insects of Special 
Interest from Florissant. Colorado, and other points in the Tertiaries of 
Colorado and Utah, by S. H. Scudder. 1892; 35 pp., 3 pi. No. 94, The 
Mechanism of Solid Viscosity, by Carl Barus. 1892; 138 pp., 24 fig., 59 
tables. No. 95, Earthquakes in California in 1890 and 1891, by E. S. 
Holden. 1892; 31 pp. No. 96, The Volume Thermo-dynaniicsof Liquids, 
by Carl Barus. 1892; 100 pp., 8 pi., 13 fig. No. 100, Bibliography and 
