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. C. A. K. 



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- 



