REVIEWS OF RECENT LITERATURE. 
ZOÓLOGY. 
Two Important Papers on North-American Mammals. — The 
literature relating to recent work on North-American mammals is so 
scattered, and the results have been the outcome of investigations 
by such a number of different workers, and based on such varying 
amounts of material, that it is a great gain when a competent author- 
ity on any given group can go over it and coórdinate the efforts of 
his predecessors in the light of, practically, all of their material, 
combined with a vast amount in addition. In other words, the 
monographic revision of any of the larger genera of North-American 
mammals by an expert is a distinct advance, for which all mammalo- 
gists may well feel grateful. It is with pleasure, therefore, that we 
call attention to two recent contributions of this character — Mr. 
Vernon Bailey's * Revision of American Voles of the Genus Micro- 
tus," and Mr. W. H. Osgood's “ Revision of the Pocket Mice of the 
Genus Perognathus." 
Mr. Bailey's revision! of the American voles, or meadow mice, is 
“ based on a study of between five thousand and six thousand speci- 
mens from more than eight hundred localities, including types or 
topotypes of every recognized species with a known type locality, 
and also types or topotypes of most of the species placed in syn- 
onymy." With such material at command, and with a wide experi- 
ence with the animals in life, and personal knowledge of the actual 
conditions of environment over a large part of the range of the group, 
Mr. Bailey has had peculiar advantages for his work, and his results 
are subject to revision only at points where material is still deficient, 
or from some other point of view. This revision, while obviously 
not final, presents a new starting point for future workers, and is 
likely to be a standard for many long years to come 
The little animals here treated are the short-tailed field mice, 
! Revision of American Voles of the Genus Microtus. By Vernon Bailey, 
Chief Field Naturalist, Division of Biological Survey, U. S. Department of Agri- 
culture. Prepared under the direction of Dr. C. Hart Merriam, Chief of the 
Division. North American Fauna, No. 17, pp. 1-88, with 5 plates and 17 text- 
figures. Issued June 6, 1900. 
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