270 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
The same thing is also well seen in the Arctic Hare (Lepus iimidus), in com- 
paring Newfoundland specimens with those from the arctic coast, or those 
of Ireland and the mountains of Central Europe with those of Scandinavia. 
The Northern Hare also presents a somewhat parallel variation to that seen 
in L. sylvaticus in passing from the Atlantic coast to the Rocky Mountain 
region. In even arctic specimens, there is always, in the winter pelage, a 
pale rufous zone underlying the white color of the surface, which in turn 
has still a plumbeous zone beneath it. In winter specimens from the Rocky 
Mountains, the white of the surface often extends to the very base of the 
fur, the rufous and plumbeous zones being both undeveloped. Passing still 
farther westward, we meet, in the Columbia River region, a phase in which 
the summer pelage is even more rufous than in specimens from the Atlantic 
coast under the same parallels. ‘The difference between northern and southern 
specimens in summer livery consists not so much in the absolutely darker 
color of the southern examples as in the greater intensity of the rufous, 
while the form living in the middle elevated region of the continent differs 
from those of both the Atlantic and Pacific coasts in the almost entire sup- 
pression of the rufous tint that forms the prevailing hue in the others. 
The only other species of this family having a very extended habitat 
are the Lepus aquaticus, which ranges from the Gulf States to Yucatan and 
Central America, and the Lepus callotis, found throughout the dry interior 
from Southern Wyoming and Nevada far down upon the Mexican plateau. 
In the former, the variations in color between specimens from the most 
extreme points of its range are almost inappreciable; while, in the latter, 
there is a considerable increase ef rufous to the southward. 
In respect to general size, the variation with locality is not more marked 
than is that of color; specimens from northern localities being generally not 
much larger than those from southern localities. I know, in fact, of no 
species of American mammals which so nearly form an exception to the 
almost universal law of a decrease in size with the decrease of the latitude 
under which they live as do some of the species of the Leporide. Yet, in 
the majority of instances, the law is here also borne out. Taking the skull 
as the most convenient element on which to base-a comparison, it is found 
(see Table I) that a series of specimens of Lepus americanus from New 
York, Pennsylvania, and Massachusetts averages /arger even than another 
series from Norway, Me.; while the latter averages larger than another series 
