346 
REVIEWS. 
FRESH-WATER RHIZOPODS.* 
W E often enough, hear of the great effects produced in the world by the 
smallest organisms ; and one of these seems to he their giving origin 
to big hooks. Ehrenberg’s Infusionstheichen and Mikrogeologie are large 
folios, and many authors have devoted stout quarto volumes to the publica- 
tion of their researches upon Infusoria, Foraminifera, and Radiolaria. To 
this number we have to add Prof. Leidy, who has just brought out a mag- 
nificent volume upon the fresh-water Rhizopods of North America. This 
work is a posthumous publication of the defunct Geological Survey of the 
Territories, which, under the able superintendence of Dr. F. V. Hayden, did 
so much admirable work in various departments of natural history ; and we 
are glad to see that, notwithstanding the change that has taken place in 
the arrangements of the United States Surveys, the investigations inaugu- 
rated and carried on by Dr. Hayden and his assistants are not likely to be 
lost to the world. 
Prof. Leidy has devoted several years to the investigations of which 
the results are published in the work now before us. Besides collecting 
assiduously in the vicinity of Philadelphia and other parts of Pennsylvania, 
in New Jersey, Connecticut, Rhode Island, and Nova Scotia, on the Atlantic 
side of the continent, he has devoted two seasons to an examination of the 
forms inhabiting some of the far distant regions of the west — especially the 
Bridger Valley, in the south-west of Wyoming, and the Uinta Mountains, 
in the same region. In the last-mentioned locality he pursued his researches 
up to an elevation of 10,000 feet. 
Of course it is unnecessary to say that such investigations do not by any 
means make us acquainted with all the forms of the groups here treated of 
which may be found within the vast territories of the United States, nor 
does Prof. Leidy claim to have even approximately exhausted his subject. 
* Report of the United States Geological Survey of the Territories. Vol. 
XII. Fresh-ioater Rhizopods of North America. By Joseph Leidy, M.D. 
4to. Washington: Government Printing Office, 1879. 
