578 Distribution of Colours in the Animal World. [October, 
rise the more intense are the colours which we en- 
counter. 
With this proposition we can scarcely agree. A mountain 
fauna is generally speaking more sombre than that of the 
adjacent plains, — a remarkable contrast to the Alpine flora. 
This faCt has indeed been cited as an argument against 
Mr. Grant Allen’s theory of the colouration of animals. 
Species confined to islands have often darker colours 
than those inhabiting continents. This conclusion holds 
strikingly good as regards many varieties inhabiting small 
islands. 
It will be seen that the colouration of any given fauna, is 
a result depending on a complex of factors, the respective 
influence of which it will not be easy to estimate. 
The different zoo-geographical regions of the earth seem 
to have certain more or less predominating colours. 
In the PalsearCtic region white, grey, black, and yellowish 
are frequent ; in the Ethiopian, yellow and brown ; in the 
Neotropical, green and red predominate ; in the Indian the 
yellow tones occur very plentifully ; whilst in the Australian 
dark colours, and especially black, take the lead. 
Generally speaking, throughout the animal kingdom the 
more bulky forms have more monotonous colours than 
smaller forms belonging to the same group. 
In almost all groups of animals those parts which are less 
visible are often brightly coloured or spotted, whilst the 
other parts of the body are more frequently uni-coloured and 
dark. Here, however, we are reminded of the very nume- 
rous cases in inseCts where the brightest colours appear to 
be seated in projecting parts, such as the extremity of the 
abdomen, the tips of the elytra in Coleoptera and Hemiptera, 
the margins of the wings in butterflies, &c. So frequent is 
this phenomenon that some naturalists have thought it a 
protective arrangement, — a bird, e.g., being more likely to 
strike at these brightly-coloured out-lying parts than at the 
more sombre vital regions. 
Sexual colours are direCtly connected with the general 
development of animals. The males have in general brighter 
colours. In many cases, however, where the females are 
larger and stronger than the males, they, in turn, are the 
more gaily coloured. 
The colouration of young animals is often very different 
from that of the adults, and — where a sexual difference 
exists — it generally resembles that of the female, in which 
consequently “ Neotenism” (see “ Journal of Science,” 1884, 
p. 53 1 ) is recognised. In many cases the young of different 
