ASSIMILATIVE COLOURATION. 379 
drawers, the mysterious wonder in the galleries of our museums, 
the charm of travellers abroad, and appreciative lovers of nature 
at home. Very much, when the difficulty of the problem is 
considered, and especially where the utility of animal disguises 
and mimicking appearances has been unravelled by the magic 
wand of “natural selection,” or ‘“‘the survival of the fittest.” But 
very little when we wish to understand the larger element in the 
phenomena of colour, to which we are, at present, unable to take 
the initiatory steps of defining its exact purpose in the battle of 
life. Some colour-development appears to be inscrutable as the 
green bones in the Mud-fish (Protopterus annectans), and the 
common Gar-fish (Lepidosteus sp.). As Darwin remarks, in the 
Hornbill (Buceros bicornis) the inside of the mouth is black in 
the male and flesh-coloured in the female.* In the twelve-winged 
Bird of Paradise (Seleucides nigricans) the mouth and throat are 
of a “‘vivid grass-green colouring,” which was seen by Guillemard 
in the course of feeding, when the bird threw a cockroach in the 
air and caught it lengthways.t At St. Kilda, Mr. R. Kearton 
describes how on a small ledge of rock in the mouth of a cave 
“I observed a little patch of brilliant orange colour appearing 
and disappearing simultaneously with the sound,” which that 
writer was endeavouring to unravel: ‘“‘it was the open mouth 
of a Black Guillemot.’’{ In the Transvaal, the writer was 
informed by a poultry fancier of Pretoria that his imported 
White Leghorns lose the yeliow colour of their legs; the young 
chickens exhibit that colour, but again lose it as they grow older. 
The body cavity of some Lizards is deep black; the pigmentation 
does not affect the entire lining of the body cavity, but only a 
part of it which is sharply differentiated from the rest; the 
palate of the Ourang-outan is black, that of the Chimpanzee 
flesh-coloured, with no pigment at all.§ In the preparatory 
stages of Lepidoptera there appears to be, as a rule, no relation 
either in tint or brilliancy of colour between larva, pupa, and 
imago.|| But there are exceptions, as in the case of that well- 
* “Descent of Man,’ 2nd edit., p. 426. 
+ ‘Cruise of the Marchesa,’ 2nd edit., p. 434. 
{ ‘With Nature and a Camera,’ p. 61. 
§ Beddard, ‘Animal Colouration,’ 2nd edit., p. 10. 
|| So among Molluses— The colour of the shell does not necessarily 
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