380 TJic American Geologist. June, i9dO 
among the brachiopods of the Chonopectns sandstone is to be consid- 
ered as weightier evidence than the holdover pelccypods and cephalo- 
pods." 
In conclusion it is stated: "In the interior of the North American 
continent, the dividing line between the Devonian and Carboniferous 
ijeriods is not sharply defined, like that betvi'een the Ordovician and 
Silurian, for instance, but judging from the association of genera and 
species alone, the fauna under consideration, and indeed all the 
Kinderhook faunas, should be placed in the Carboniferous. However, 
if it can in any way be demonstrated that the strong Carboniferous 
clement in the fauna had its point of origin right here in the Missis- 
sippi valley, and that these types of life existed here earlier than in 
any other part of the world, their presence in other regions being due 
to migrations of life from this region, then there maj' be some founda- 
tion for considering a part or the whole of the Kinderhook as being 
the very youngest Devonian. It yet remains to be demonstrated, 
however, whether the Kinderhook holds such a relationship to the 
Carboniferous of other parts of the world." 
The stratigraphic section of Burlington is taken as a basis, with 
the various dividing lines essentially the same as established by Hall, 
and later adopted by other writers. 
Altogether the paper is timely; and a valuable addition to our 
knowledge of the Kinderhook. Only one point arises, if one might 
be inclined to criticize. In a paper of a monographic character great- 
er completeness would be expected. Not nearly all of the species 
known to occur in the yellow sandstone of Flint river are considered. 
If it was only intended to take up the forms described chiefly by 
White, Whitfield and Winchell. no mention is made of this restriction. 
C. R. K. 
TJie Glacial Gravels of Maine and their Associated Deposits. By 
George H. Stone. Monographs of the U. S. Geol. Survey, Volume 
XXXIV. Pages xiii, 499; with 52 plates, and 36 figures in the text. 1899. 
Price, Si -30. 
In this volume we welcome the publication of the results of sur- 
veys and studies which were begun in 1876 and were substantially 
completed, as the author states, in 1889. The central theme is the 
description of prolonged gravel ridges which were formed during the 
final recession of the ice-sheet, with consideration of the conditions 
of their origin. These eskers or osars, known more commonly to 
the people of Maine by their local name, "horsebacks," extend from 
south to north, or northwesterly, varying in length from a few miles 
to more than a hundred miles, in approximately parallel series or sys- 
tems, fifty or more in number, many of them receiving branches. The 
main line of each system coincides nearly with the course in which 
the ice-sheet moved, but the branches often run transversely many 
miles, coming from either side like tributaries of a river system. Pro- 
fessor Stone very thoroughly describes these remarkable gravel ridges, 
which are equalled or surpassed in no other region, excepting Sweden. 
