<6 ERS SN 
238 BULLETIN NO. VII. 
‘ 
formly traceable, being generally present in specimens from 
about Washington, but much stronger in those from S. Carolina 
and Florida, in which it generally forms a strong, broad bar, 
though sometimes obsolete.” 
The amount of black i. e. the length of the black tips of the 
coarser hairs is variable in the same locality, seasonally and 
otherwise, 
Winter specimens are lighter than the same individuals in 
summer, and the difference is apparently greatest to the north. 
Our Minnesota winter specimens are very light colored. Al- 
though there seems to be a tendency to a decrease in size 
southward according to the usual law, it is slight and speci- 
mens from Mexico are as large as northern individuals. The 
local peculiarities of station seem to have a more direct influ- 
ence than the general geographical influences. 
‘‘Southern specimens generally have the ears less covered 
han nortnern ones, the feet less heavily furred, and the gen- 
eral pelage harsher and less full. Southern specimens also 
show a tendency to decidedly longer ears than the northern 
ones.” This is in accordance with the law, an increase of 
mean annual temperature and humidity tends to cause greater 
development of apendicular parts. 
VAR. NUTTALLI. 
This variety expresses the law that treeless, dry regions 
tend to diminish the intensity of coloring. ‘‘The lightest 
specimens appear to be those from western Wyoming, Colorado, 
Nevada and Utah, Arizona specimens passing gradually into 
var. arizone.” In size there is some difference, the present 
variety being, according to Allen, about twelve per cent.smaller. 
The proportions are the same and the difference in size has 
usually been overestimated. Northern specimens have dense 
soft fur and heavily-clothed ears and feet. The paleness is due 
to a suppression of the yellowish or fulvous subterminal rather 
than the black terminal portion of the coloring. 
VAR. ARIZONE 
is the extreme of the tendency expressed by the above but with 
the addition of considerably elongated ears, they being one- 
third longer than those of types of the above variety. This ~ 
variety was founded upon some six specimens, of which part 
at least were young, and we await with interest the accumula- 
tion of additional material. 
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