No. 498] 



FAUNAL AFFINITIES 



393 



These facts, it seems to me, point strongly to the con- 

 clusion, that, as far as terrestrial vertebrates are con- 

 cerned, the intermediate character of the environmental 

 conditions makes of the prairie region an extensive area 

 of transition between the plains and eastern forest 

 regions, but that the environmental conditions are not 

 either intensive or extensive enough to mold the forms 

 into a peculiar fauna. 



Beferences. 



1901. Bray, W. L. The Ecological Eelations of the Vegetation of Western 

 Texas. But. Gaz., XXXII, 99-123, 195-217, 262-291. 



1900. Pound and Clements. The Phytogeography of Nebraska, Lincoln. 



1908. Euthven, A. G. Variations and Genetic Relationships of the Garter- 

 snakes. Bull. U. S. Nat. Mus., 61. (In press.) 



1906. Tower, W. L. An Investigation of Evolution in Chrysomelid Beetles 



of the Genus Leptinotarsa. Carnegie Inst., Pub. No. 48. 

 1905. Transeau, E. N. Forest ( 'enters of Eastern America. Amer. Nat., 

 XXXIX, 875-889. 



1884. Sargent, C. S. Forests of North America. 10th Census ot the 

 U. S.., IX. 



1907. Whitman, C. O. The Origin of Species. Bull. Wise. Nat. Hist. Soc, 



