506 
APPENDIX E 
Probably it is an example of what is known as directive coloration, 
of coloration used for purposes of advertisement or communication 
with the animal’s followers. But however this may be, it is certain 
that there is not the smallest justification for Mr. Thayer’s theory 
so far as the prongbuck is concerned. 
It is practically the same as regards the rabbit or the hare. 
Anyone who has ever been in the woods must know, or certainly 
ought to know, that when hares are sitting still and trying to 
escape observation, they crouch Hat, so that the white of the tail 
and rump is almost concealed, as well as the white of the under 
parts, while the effect of the counter-shading almost or entirely 
vanishes. No terrestrial foe of the hare would ever see the white 
rump against the sky-line unless the animal was in rapid motion 
(and parenthetically I may observe that even then it would only 
see the rump against the sky-line in an infinitesimally small number 
of cases). Of course, as soon as the animal is in motion it is 
conspicuous to even the most dull-sighted beast of prey ; and 
Mr. Thayer’s idea that the white rear patch may mislead a foe as 
it jumps upon it is mere supposition, unsustained by any proof, 
and contrary to all the facts that I have observed. Civilized man, 
who is much more dull-sighted than most wild things, can always 
see a rabbit when it runs because its white is then so very con¬ 
spicuous. Here, again, I do not think there is the slightest value 
in Mr. Thayer’s theory. The white rump is certainly not a pro¬ 
tective or obliterative marking; it is probably a directive or 
advertisement marking. 
The Virginia deer, utterly unlike the prongbuck, does often seek 
to evade observation by lying close, or skulking. When it lies 
close, it lies flat on the ground like a hare, and its white tail is 
almost invisible, while of course even the most low-creeping foe 
would not under such circumstances get it against the sky-line. 
When it skulks, it moves off* with head and neck outstretched and 
tail flattened down, with the white as much obscured as possible. 
The white is never shown in conspicuous fashion until the animal 
is frightened and no longer seeks concealment. It then bounds off* 
openly, crashing through the bush, with its white tail flaunted, 
and under such circumstances the white mark is extremely con¬ 
spicuous. 
Indeed, I feel that there is grave ground to question the general 
statement of Mr. Thayer that “ almost all mammals are equipped 
with a full obliterative shading of surface colours; that is, they 
are darkest on the back and lightest on the belly, usually with 
connected intermediate shades.” This is undoubtedly true as a 
statement of the coloration, but whether this coloration is in 
fact obliterative needs further investigation. Of course, if it is 
obliterative, then its use is to conceal the mammals. Mr. Thayer’s 
