PUBLICATIONS. 595 
some in our own, students wishing to get a clear idea of the founda- 
tion principles of the subject have been obliged either to wade through 
volumes of technical English works or to materially lessen their 
interest in the subject by struggling with the difficulties of a foreign 
language. The author presents in a condensed form the principal 
structural features of invertebrate fossils, and gives the generally 
accepted classification, with clear descriptions of the larger groups and 
principal genera. The book though perhaps too elementary for those 
taking up the study of paleontology with the intention of devoting 
considerable time to it, could still be used with profit for some time 
by such students. Its greatest usefulness will be, however, in aiding 
those who take up the natural sciences, for general culture only, to get 
a clear idea of the subject without becoming confused by a mass of 
details. J. Ce Me 
Geological and Natural Fiistory Survey of Minnesota. N. H. Win- 
CHELL, State Geologist, 1885-92. Geology of Minnesota, 
Wolk, IU0G, leewer Jl, Jeimal Imeoomt, Jalesomtolosy, ly ILeo 
Lesquereux, Anthony Woodward, Benjamin W. Thomas, 
Charles Schuchert, Edward O. Ulrich, Newton W. Winchell. 
41 plates and 34 figures, pp. Ixxv.+-474. Published by the 
state. Minneapolis, Minn., 1895. 
This important report opens with an excellent historical sketch of 
previous investigations of the Lower Silurian formations of the Upper 
Mississippi Valley by Professors Winchell and Ulrich. Students of the 
region will find this very convenient in directing them to the literature 
of the subject not only, but in giving them some indication of the 
conclusions reached in the works referred to. This is followed by a 
chapter on the Cretaceous fossil plants of Minnesota by the veteran 
palzobotanist, Leo Lesquereux. In the introduction to this, atten- 
tion is called to the remarkably abrupt substitution of the Cenozoic 
flora for the Mesozoic flora in the midst of the Cretaceous period, and 
emphasis is laid upon the great diversity of the dicotyledonous forms 
upon their first appearance, and the lack of any satisfactory explanation 
of this phenomenon at present. Twenty-three species are described, of 
which seven are new. This is followed by a chapter on the micro- 
scopic fauna of the Cretaceous deposits in Minnesota, with additions 
from Nebraska and Illinois, by Anthony Woodward and Benjamin W. 
