1916] Dice: Land Vertebrates of Southeastern Washington 341 



Zones or belts of life may be recognized in many regions. How- 

 ever, it is very difficult to homologize the zones of life which occur in 

 widely separated parts of North America. The division of the conti- 

 nent into a definite number of transcontinental life-zones seems to be 

 contrary to a number of the facts of distribution. 



The ecological method of studying distribution furnishes valuable 

 information about the relation between organisms and their environ- 

 ments. The use of this method in conjunction with the zoogeographi- 

 cal method should lead to results of great value. 



LITERATURE CITED 



ADAMS, C. C. 



1908. The ecological succession of birds. Auk, 25, 109-153. 

 ALLEN, J. A. 



1892. The geographical distribution of North American mammals. Bull. 

 Amer. Mus. Nat. Hist., 4, 199-244, 4 maps. 



BlGELOW, F. H. 



1908. The daily normal temperature and the daily normal precipitation of 

 the United States. U. S. Dept. Agr., Weather Bureau. Bull. E, 

 186 pp. 

 GADOW, HANS. 



1913. The wanderings of animals (University Press, Cambridge), viii -f- 150 



pp., 17 maps. 

 GATES, FRANK C. 



1911. Summer bird life in the vicinity of Havana, Illinois, in its relation to 



the prominent plant associations. Wilson Bull., 23, 1-27. 

 GRIN NELL, J. 



1902. Check-list of California birds. Cooper Ornith. Club, Pacific Coast 

 Avifauna, 3, 98 pp., 2 col. pis. 



1914. An account of the mammals and birds of the lower Colorado Valley 



with especial reference to the distributional problems presented. 

 Univ. Calif. Publ. Zool., 12, 51-294, pis. 3-13, 9 figs. 

 GRINNELL, J., AND SWARTH, H. S. 



1913. An account of the birds and mammals of the San Jacinto area of 



southern California, with remarks upon the behavior of geo- 

 graphic races on the margins of their habitats. Univ. Calif. Publ. 

 Zool., 10, 197-406, pis. 6-10, 3 figs. 

 JACKSON, HARTLEY H. T. 



1914. The land vertebrates of Ridgway Bog, Wisconsin: their ecological 



succession and source of ingression. Bull. Wise. Nat. Hist. Soc., 12, 

 4-54, 9 figs. 

 KENNEDY, C. L. 



1914. The effects of irrigation on bird life in the Yakima Valley, Wash- 

 ington. Condor, 16, 250-255. 

 LYDEKKER, R. 



1896. Geographical history of mammals. (University Press, Cambridge), 

 xii + 400 pp., 82 figs., 1 map. 



