Reviezv of Recent Geological Literature. 6 1 
ducing the personal equation in an experiment of this kind, and while 
it may be involuntary on the part of the animal, it may be voluntary 
(but unconsciously so) on the part of the experimenter. G. F. M. 
Uber die Fauna der Bande f. i. im mittel bohmischen Silur. Von 
j. V. Zelizko. — also — Beitmg ztir Keftntttiss des Mitielcambrium 
von Jenes in Bohmen. Von J. V. Zelizko. (Verhandl. d. K. K. geol. 
Reichsanstallt, Nr. q und lo, i8q8, und Nr. i6, 1887, Wien.) 
These two pamphlets describe the result of the exploration of cer- 
tain fossiliferous localities in Bohemia; at some of which the beds of 
Bande f. I. of the Silurian are exposed, and at others the Paradoxides 
beds. The gradual increase of the fauna of Bande f.i. in the lower 
part of the Silurian to its disappearance in the upper part are shown. 
In the Cambrian beds several species rare to Barrande were ob- 
tained more plentifully and the geographical range of others extended. 
N"o figures or plates. G. f. m. 
The educational series of rock specimens cotlectei and distributed by 
tJie United States Geological Survey. By Joseph Silas Diller. (U. 
S. Geol. Survey, Bull. 150, 400 pp., 47 pis., 1898.) 
This series of rock samples, already distributed by the United States 
Geological Survey to the leading educational institutions of the coun- 
try, is here described in considerable detail. But prefacing the de- 
scriptions is a chapter on the study of rocks, written in a style which 
is as free from technicalities as is consistent with the nature of the sub- 
ject. This chapter contains: an account, with descriptions, of the 
structural features of rocks; an account of the methods of physical 
analysis of rocks; concise descriptions of the chief characters of the 
common rock-forming minerals, with references to specimens of the 
series containing each mineral; and a short section on the classifica- 
tion of rocks. These subjects are discussed in a manner which can be 
readily understood by the intelligent student, and this chapter thus 
forms a fitting introduction to the detailed descriptions which follow. 
The main part of the work is devoted to the description of the rock 
specimens. Each is taken up by itself and described macroscopically 
and in nearly all cases also microscopically. Accompanying the de- 
scriptions are many illustrations, frequently microphotographs. Chem- 
ical analyses are given of many of the specimens, and there are refer- 
ences to other sources of information concerning the rocks and the 
geological phenomena which they represent. The specimens are 
grouped under eight heads, as follows, with the number of specimens 
in each group: unaltered sedimentary rocks of mechanical origin, 22; 
unaltered sedimentary rocks of chemical origin, 16; unaltered sedi- 
mentary rocks of organic origin. 18; unaltered igneous rocks, 58: nieta- 
morphic sedimentary rocks, 21; metamorphic igneous rocks, 11; 
residual rocks, 4: illustrations of surface modifications, 6: — 156 in all. 
A large part of the descriptions were written by Mr. Diller, but 
quite a number were written by other geologists. This latter fact has 
caused a certain lack of uniformity in the manner of the descriptions 
and in tlie kinds and number of facts presented. To offset this dis- 
