340 University of California Publications in Zoology [VOL. 16 



volved. It seems impossible to organize all the facts into a perfect 

 system, but it is desirable to have as great uniformity as possible and 

 not unduly to increase systems or complexity of nomenclature. As 

 the facts become better known systems will have to be changed to agree 

 with the increased knowledge. At present it seems desirable to use 

 two systems, both starting with the same unit, the species. By the first 

 method, zoogeography, species and taxonomic groups are considered 

 in relation to geographical divisions. The second method, the eco- 

 logical method, groups species according to similarity of adapt ational 

 features and of environmental conditions. 



A combination of these two methods of studying distribution should 

 lead to excellent results. Usually the study of zoogeography has been 

 carried on without reference to the particular habitats in which the 

 organisms live. A comparison of the animals in similar habitats in 

 different faunal areas is sure to bring to light many important facts 

 about the evolution of the different groups and of topographical and 

 climatic changes in general. Further, the relation between an organ- 

 ism and its environment cannot be fully understood without reference 

 to the mode of origin both of the organism and of the environment. 



SUMMARY 



In southeastern Washington we may distinguish three faunal areas, 

 each containing a number of distinct habitats. Each habitat is occu- 

 pied by a different vertebrate association. 



The Columbia Basin sagebrush fauna belongs to the Great Basin 

 division of the Sonoran region. The Blue Mountain fauna belongs to 

 the Canadian subregion of Holarctica. The Columbia Basin prairie 

 fauna shows affinities to the life both of the Rocky Mountains and of 

 the Great Basin. 



An Upper Austral life-zone, a timberless and a timbered division 

 of the Transition life-zone, and a Boreal life-zone may be recognized 

 in the region. 



Although temperature seems to be the climatic barrier which is 

 most important in separating the faunas of the zoogeographical 

 regions (Holarctic, Sonoran, and Neotropical) represented in America, 

 yet within the limits of the Sonoran region it has not been proved that 

 temperature is as important a barrier to distribution as are the factors 

 connected with differences in rainfall and humidity. 



