66. Recent Literature. [ ZOE 
subject in a somewhat new light. The facts do not seem to bear 
out Mr. Chapman’s suggestion, however, that hybridization may 
be a means of originating new species, for, in the present instance, 
the tendency seems to be rather to merge two existing species into 
one. : a Ng 
The Geographic Distribution of Life in North America, with 
special reference to the Mammalia. By C. Hart Merriam, M.D. 
Proc. Biol. Soc. Washington, vol. VII, pp. 1-64. Fauna No. 3 of 
the Department of Agriculture was an epoch-making work in the 
literature of the geographical distribution of animals in America. 
Dr. Merriam, in the present work, has amplified and systematised 
the ideas which were there first enunciated. With the unequalled 
facilities at his command in the shape of probably the largest and 
most discriminatingly collected series of mammals that has ever been 
made from the same extent of territory, he is in a better position 
than any of his predecessors to draw conclusions with regard to the 
distribution of life in North America. : 
The paper commences with a historical synopsis of the faunal 
and floral divisions proposed for North America by various writers. 
Each division is considered separately, with a chronological table of 
the work of different writers upon it. The different life regions are 
then discussed with reference to the mammals inhabiting each. 
Considerable space is devoted to the causes controlling distribution 
and in combating certain of Wallace’s views. Dr. Merriam is 
especially pronounced in asserting the importance of temperature in 
directly affecting the distribution of animals, and his answer to Wal- 
lace with regard to the change in mammalian forms from the north 
southward is very forcibly put. The general drift of his paper is, 
that life zones are largely climatic, and consequently extend in belts 
more or less parallel to the equator rather than in a north and south 
direction, as claimed by Wallace. 
In closing, he says: “ Wallace, in writing of the principles on which 
zoological regions should be formed, expresses the opinion that 
‘convenience, intelligibility and custom should largely guide us.’ 
But I quite agree with America’s most distinguished and philosophic 
writer on distribution, Dr. J. A. Allen, that in marking off the life 
regions and subregions of the earth, truth should not be sacrificed to 
convenience; and I see no reason why a homogeneous circumpolar 
fauna of great geographic extent should be split up into primary re- 
