294 The American Geologist. May, 1892” 
regarded at once as a distinct species. Their development begins 
in the upper portion of the Trenton shales, where specimens are 
occasionally picked up at St. Paul. It is, however, not until this: 
species is found in association with Clitambonites diversa Shaler, 
that the variety becomes common and attracts one’s attention. 
In the Trenton of New York and Kentucky occasional specimens: 
are met with approaching var. /aticostata, but none of them are: 
so strongly transverse as the Minnesota individuals. 
Plate xxxtv, figs. 26-29. 
THE DRIFT OF THE NORTH GERMAN LOWLAND. 
Rouuw D. Sarispury, Madison, Wis. 
Dr. Felix Wahnschaffe, of the German geological survey, has- 
recently issued a small volume entitled ‘‘The Causes of the Sur- 
face Form of the North German Lowland.’’* As the title indi- 
cates, the volume is primarily geographical, but it discusses the 
geography of the area under consideration from the geological 
standpoint. The book is particularly welcome to American 
glacialists, since for the first time it presents in compact form the 
general conclusions which have thus far been reached in Germany 
in the field of glacial geology, and affords a convenient and ade- 
quate basis for a comparison between the corresponding phenom- 
ena of Germany and the United States. Most of the publications 
on the glacial geology of Germany, which have heretofore ap- 
peared, have been special reports on circumscribed areas. These 
publications have not been widely distributed, and are not so well 
known to American geologists, as could be desired. Dr. Wahn- 
schatfe’s publication will therefore be of great interest and service, 
since it will aid in correlating the phenomena on opposite sides of 
the Atlantic. It is the purpose of this article to review the salient 
features of Dr. Wahnschatfe’s volume, and at the same time to 
make some suggestions concerning the correlation of German and 
American glacial formations. 
The yolume has many excellencies. The author’s sense of pro- 
portion is good, and special points are not magnified at the ex- 
pense of other equally important ones. The book does not at- 
tempt more than it accomplishes. In Germany, no less than in 
*Die Ursachen der Obertliichengestaltung des Norddeutschen Flach- 
landes. pp. 166, Stuttgart: Verlag von J. Engelhorn. 1891. 
