PRELIMINARY LIST OF THE MAMMALS OF NEW YORK 289 



ing is removed boreal species disappear, while their places are taken 

 by austral forms. Instances of this process in New York have been 

 cited by Miller ('93b. p. 63) and Mearns ('98b. p. 342, 345, 

 360). The observations of the former refer to the rapid replacement 

 of the Canadian white footed mouse, Peromyscus canadensis, by its 

 more southerly relative, P. leucopits noveboracensis. Mearns says : " The 

 interioi region of the Catskills surrounding Kaaterskill Junction belongs, 

 as a whole, to the Canadian, the lowest of the boreal faunae, though 

 slightly mixed with the Alleghanian [transition] in the farming lands on 

 the banks of Schoharie creek. There is some evidence, however, that 

 certain mammals of the transition and upper austral zones, as the 

 New England cottontail (Lepus sylvaticus transitionalis), deer mouse 

 {Peromyscus leucopus), and gray fox ( Urocyon cinereoargenteus), have but 

 lately extended their ranges to this locality by following up the clearings. " 



The explanation of the climatic changes that induce this alteration in 

 fauna would involve a more thorough knowledge of forest influence 

 than is now available. Much could be done toward a solution of the 

 problem by a thorough biologic and climatologic survey of a small 

 Canadian area on the southern edge of the Adirondacks. After the 

 normal conditions under which the Canadian fauna existed were well 

 understood the area should be cleared and reduced to the condition of 

 a brushy pasture. This would give opportunity for a duplicate set of 

 observations after the change in fauna had taken place, and from a com- 

 parison of the two sets, important conclusions would undoubtedly be 

 reached. . 



Upper austral zone. The upper austral zone enters New York in 

 two widely separated regions, the Hudson valley, and the extreme 

 western part of the state in the " lake region." 



In addition to the southern species already mentioned as extending 

 their ranges into the transition zone the strictly characteristic mammals 

 of the austral zone are : 



Didelphis virginiana opossum 



Tamias striatus siriatus southeastern chipmunk 



Peromyscus leucopus leucopus southeastern white-footed mouse 



Neotoma pe7insylvanica cave rat 



Lepus floridanus mallurus southeastern cottontail 



Urocyon cinereoargenteus g rav f° x 



Pipislrellus subflavus subflavus Georgia bat 



Pipistrellus subflavus obscurus 1 dusky bat 



1 The f aunal position of this bat Is not positively known. 



