PRELIMINARY LIST OF THE MAMMALS OF NEW YORK 319 



1856 Arvicola dekayi Audubon & Bachman, Quadr. N. Am. 3 :287. 

 1884 Evotomys rutilus gapperi Merriam, Linn. soc. New York. Trans. 



2: 173. 

 1 891 Evotomys gapperi Merriam, North American fauna. 30 July 



189 1. no. 5, p. 119. 

 1898 Evotomys gapperi Mearns, U. S. Nat. mus. Proc. 21 : 349. 



Type locality. Region between York and Lake Simcoe, Ontario 

 Canada. 



Faunal position. While the common red-backed mouse is a typical 

 Canadian animal, in sufficiently cool, damp localities it penetrates con- 

 siderably to the south of the normal geographic limits of the boreal zone^ 



Habitat. In the northern part of its range this mouse is found in 

 almost every variety of surroundings, but further southits habitat becomes 

 more limited. In the Canadian zone it is one of the most widely dis- 

 persed mammals, in the northern part of the transition zone it is restricted to 

 damp woods, while in the lower part of the transition zone it is never found 

 faraway from cold streams, wooded sphagnum bogs and cedar swamps. 

 Mr Charles H. Batchelder has recently described the conditions under 

 which the red-backed mouse occurs in the transition zone of eastern 

 Massachusetts. He says, " What these favorable conditions are, is the 

 most interesting question connected with the animal's [local] distribution, 

 but it is not one that can receive a positive and final answer. Neverthe- 

 less there are some characteristic features that are common to almost all 

 of the places where I have found it [in southeastern New England]. 

 One may look for it with some confidence in almost any large tract of 

 wet ground that retains its moisture through the summer, but is not subject 

 to serious floods, and which bears a growth of woods sufficiently heavy to 

 afford a dense shade, so that the ground beneath and the roots of the trees 

 are covered with a deep carpet of sphagnum. If the older trees have 

 been suffered to die a natural death, and their stumps and fallen trunks 

 lie slowly rotting on the ground half- concealed by the sphagnum, the 

 chance of finding it is certainly not lessened. One of the most evident 

 peculiarities of such a spot as this, in southern New England, is that the 

 dense shade and the abundant evaporation maintain a temperature dur- 

 ing the hottest summer weather that is far below that of the surrounding 

 country. In these respects of coolness, moisture and shade there is a 

 striking resemblance to the woods Evotomys gapperi inhabits in extreme 

 northern New England and other parts of the Canadian zone. 



" The places where I have found it differ considerably in their appear- 

 ance, chiefly according to the kinds of trees with which they are wooded. 



