96 
south eastern portion of European Russia. He concludes that this 
black colour is due to an accumulation of vegetable matter from the 
herbaceous plants of the poorly drained steppes of the post glacial 
deposits which overlie the loessoid clays, so difficultly permeable to 
water. At the close of this paper he draws attention to the close cor- 
respondence which exists between the climate of Russia and that of the 
prairie land of Minnesota, and suggests the probable similarity of the 
soils of these regions. 
" The above analyses make it to appear that the Tschernozem and 
the soil of the Red River prairies are similar in chemical composition ; 
they occur in the same latitude, with the same general relief and climate, 
and from the above quoted authorities are judged to have a similar geo- 
logical history ; may they not, therefore, be properly considered as of 
the one variety of soil, " Black Earth." 
BOOK NOTICES. 
Scudder, S. H. A Brief Guide to the Commoner Butterflies of 
the United States and Canada. 121110., 12 + 206 pp. Henry Holt & 
Co., New York. 
In our August, 1892, number we gave notice of a Butterfly book 
for boys which Mr. Scudder had in preparation. We took occasion 
then to point out the advantage of all young people having some hobby 
in natural history, and looked forward with pleasure to the early appear- 
ance of this work, which should, we thought, act as a first stepping stone 
from which young students might find an easy entry to one of the most 
attractive fields of study offered to us by Mother Nature. Such a book, 
which was much wanted, has now been prepared by Mr. Scudder in his 
characteristic manner, and has been published by Messrs. H. Holt & 
Co. as a neat duodecimo of convenient form, well printed and got up. 
This little work treats only of the commonest butterflies, such, in fnct, 
as any energetic collector in the Northern States or Canada is pretty 
sure to take within a year or two. It is to be followed by a more com- 
plete Manual of the Butterflies of North America, north of Mexico, to 
hi- issued at an early date, and prepared in a similar style to Cray's 
M.mual of the plants of the Northern States. Mr. Scudder's Brief 
