54 
The American Geologist. 
January, 1886 
actual. Their optic properties are not presented except iu a summary 
statement in the introduction. In the same connection brief statement 
is given of elasticity, hardness, cleavage and thermal and magnetic 
properties. 
The plan of the author is very logical and progressive. While a con¬ 
sistency in succession of topic after topic is observable, no term is em¬ 
ployed until it has been defined. Thus, starting from a point, which is 
taken as the “origin,” the author builds about it in a series of growths, 
linked by rational and even by geometric relations, the different essen¬ 
tials of crystals, axes, planes, indices, intercepts, symmetry, projection, 
zones, and finally all the forms of the six crystallographic systems, with 
their modifications by twinning, mero-syinmetry, etc. A pleasant char¬ 
acteristic of the treatise is the paucity of mathematical reasoning. The 
results of mathematical processes are announced in such exact and 
convincing terms that, in the absence of the demonstrations, the gist 
and the truth of the argument are equally apprehended. Thus it is 
more readable than many such treatises. In this respect it is compar¬ 
able to Jameson’s condensed statement of Hatty’s crystallography of 
1801, published by Jameson in 1817. Chapter IX is devoted to the 
measurement and calculation of the angles of crystals and chapter X to 
the representation of crystals. 
Altogether it is the most voluminous and comprehensive work in the 
English language devoted to the morphology of crystals, and perhajjs 
marks as important a place in the progress of crystallography as that of 
Miller, published in 1839. n. h. w. 
Einige Beitrdge zur Kenntniss dev bohmischen Kreideformation . 
By Jaroslay J. Jahn. (Jahrbuch der k.k. geolog. Reichsanstalt 
[Wien], 1895, Bd. 45, Heft 1.) This memoir contains an account of the 
Cephalopoda of the Priesener schist (or shale) and of the horizontal 
distribution of this group, as well as a description of the Teplitzer and 
Iser schist in eastern Bohemia. The memoir is accompanied by a plate 
in which six varieties of the genus Scaphites are figured (referred to 
S. geinitzi and S. fritschz) and one of Baculites (referred to B. faujassi ); 
the author also figures, but does not name or describe, a new species of 
this genus. The majority of the fossils of the Priesener schist are of 
Turonian types, though a number are Lower Senonian. On the whole 
it may be regarded as equivalent to the Grey Chalk of England. The 
Teplitzer schist is an older part of the Cretaceous. Sections of these 
deposits are shown by woodcuts accompanying the text, and there are 
lists of fossils from various localities. g. f. m. 
Dictionary of Altitudes of Missouri. By C. F. Marbut. (Missouri 
Geol. Survey, vol. vm, pp. 227-316. Jefferson City, 1895.) The eleva¬ 
tions of the various cities and towns have been determined in the main 
from railway levels. The altitudes as thus derived have been carefully 
compared and corrected to agree with various lines of precise levelling 
run by the Missouri and Mississippi River Commissions and the United 
States Coast and Geodetic Survey. The material is arranged in die- 
