1875.] Difficulties of Darwinism. 325 
former to the royal tiger could have no deterrent effect upon 
lesser beasts of prey in a country like Africa, where the 
scourge of India is unknown. The general structure of the 
giraffe differs far too widely from that of the leopard to 
admit of the one being mistaken for the other. But we 
may even feel some doubt whether a concolourous animal is 
more easily seen than one that is striped, spotted, or clouded. 
No animal presents such a vast extent of self-coloured sur- 
face as does the elephant; yet all eastern sportsmen admit 
that, whether escaping or acting on the offensive, he has a 
wonderful power of remaining unseen at remarkably short 
distances. We must, therefore, I think, admit that in the 
colouration of the Mammalia there are points which cannot 
be explained by the do¢trine of Natural Selection. 
Passing to the great class of birds, we find, as regards 
colour, the most complete difference. In place of the 
poverty of tone and design characterising the Mammalia, 
we have here, probably, every conceivable colour, and pat- 
terns the most elaborate. Why such meagreness on the 
one hand, and such prodigality on the other? Is it in 
virtue of Natural Selection? We are certainly warranted 
in assuming that a coat of many colours may draw upon 
either bird or beast the observation of its enemies. We 
may think that the bird, having the power of flight, can 
more readily escape from its pursuers, and can thus—if we 
may use the expression—afford to be more showy. But in 
many gaily clad birds the power of flight is so limited as to 
afford them small protection against carnivorous beasts and 
reptiles. Birds, too, are more exposed to the attacks of 
eagles, hawks, and other predatory members of their own 
class, than are any—save the very smallest—beasts. So 
that we may well doubt if the feathered species do really 
enjoy any greater immunity from danger than do Mammalia. 
Nor must we overlook the fact that the winged mammals, 
the bats, are sufficiently sombre in their attire. Is it Sexual 
Selection ? We may suppose that hen birds select mates of 
the richest plumage, whilst female beasts display no such 
preference. But then comes the question—Why is there 
such a difference of taste between the two great classes of 
warm-blooded vertebrates? To this question it is difficult to 
return any answer which is not substantially a reference to 
some inscrutable decree of the Creator. But there is the 
further difficulty that all birds do not display splendid hues 
and exquisite designs ; many species are as dull and plain 
as the beasts of the field. 
It is impossible to deny that the plumage of the Raptores 
