26 MOSTLY MAMMALS 
and is correlated with the presence of foliage on the trees 
at the one season and its absence at the other. It may 
be added that the white-tail and the muntjac have the 
under-side of the tail and the inner surfaces of the buttocks 
white, and thus display a conspicuous patch when running 
to covert with the tail elevated. _Somewhat curiously, the 
roe generally develops a white rump-patch only when in 
the grey winter dress. 
Although the reason for many details remains to be 
worked out—and for this naturalists must rely on the good 
offices of sportsmen—I venture to think that the foregoing 
theory affords a satisfactory explanation of most of the 
different types of coloration prevailing among the deer. 
Probably the coloration of the chital—spotted at all seasons 
—was the primitive type. From this was evolved the 
seasonal change characteristic of the fallow and Peking 
deer, and from this, again, the absence of spots at all 
seasons distinctive of the white-tail and roe. A further 
specialisation is displayed in the tropics by the sambar 
in one direction and the muntjac and barasingha in the 
other. If these conclusions be well founded, it is evident 
that deer were originally a tropical group. It should be 
mentioned that the Indian hog-deer, which develops spots 
in summer, is an exception to the rule that tropical deer, 
if spotted at all, retain their markings all the year. 
The foregoing summary of the extent of our knowledge 
—or, rather, of the depth of our ignorance—with regard 
to the meaning and object of the different types of colora- 
tion prevalent among the larger mammals may, it is to be 
hoped, direct the attention of travellers and sportsmen to 
an extremely interesting, but much neglected, subject, and 
thus lead to a real advance being made in the interpreta- 
tion of the facts. 
