766 THE AMERICAN NATURALIST. [Vor. XXXIX. 
is especially intended to elucidate the formation of soils and surface 
deposits and as such holds a unique place in special texts for the 
instruction of students in agriculture and forestry. The chapters on 
the igneous rocks surpass those in most text-books of geology for the 
general student; and in the field covered by the book the author has 
done a notable service in informing the general student concerning 
the important surface changes involved in the weathering of rocks. 
The work is now so well known to students and teachers of geology 
that it does not seem necessary to call further attention to the subject- 
matter of the reprint. It isto be regretted that so important a work 
should retain so many typographical errors. For this defect the 
electrotype process, the special character of the treatise, and the 
probable limited sale of the work, must be held responsible at this 
time. 
jc: B We 

Notes.— “ The Geology of the Hudson Valley between the Hoosic 
and the Kinderhook,” by J. Nelson Dale, has appeared as Bulletin 
242, of the United States Geological Survey. This paper serves as 
a supplement to the work previously published as Monograph 23 
(1894), and gives a series of maps and cross sections from the west- 
ern Hoosic River to the longitude of Albany. . "T 
Bulletin 238 of the United States Geological Survey is by Adams, 
Haworth, and Crane, and has for a title “ The Economic Geology of 
the Iola Quadrangle, Kansas." Nearly three quarters of the report 
deals with the oil and gas production of this region. The oil and 
gas are derived. mainly from the Cherokee shale, which is the lowest 
member of the Pennsylvanian, or Lower Carboniferous, series. The 
character and distribution of the Kansas oil seems-to point-clearly to 
an organic origin. ; xs kant 
C. W. Wright, after a short visit to Alaska, has extended the 
knowledge of the placer fields by a description of “ The Porcupine 
Placer District, Alaska ” (Bulletin 236, United States Geological Sur- 
vey). In this paper, Mr. Wright points out that the gold found in 
the placers is mainly derived from local sources, namely, a series of 
mineralized slates, possibly of Lower Carboniferous age. © 
» M: publication is to afford topographers, both in the field and in 
e ofice, a Convenient compendium of necessary tables and formulas: 
