INTRODUCTION. xvil 
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safety in an open nest. One of the most striking instances is to be 
found in the birds forming the genus Malurus. The males are often of 
the most gorgeous tints, which are assumed exclusively in the nuptial 
season ; and in many cases, at least, it is known that they do not assist in 
incubation. There are several possible explanations of these interesting 
facts. The domed nests may be for the purpose of shielding the sitting bird 
and its charge from cold, or rain, or from some special enemies. It must also 
be borne in mind that throughout this group the eggs are conspicuous, and 
this may to some extent influence the mode of nidification. If we grant 
that these domed nests are built for other purposes than the concealment 
of the sitting female, it is easy to explain the great difference of colour 
between the sexes. The more brilliant colours of the males have been 
obtained by sexual selection ; for in genera nearly allied to Malurus, such 
as Séipiturus, Dasyornis, Spheneacus, the sexes are alike and dull in 
colour, but the nests are always domed and the eggs more or less con- 
spicuous—a convincing proof, I think, that the nests are not so built to 
conceal any showy colours in the parent birds. As previously stated, in 
many cases the showy male bird of many of the species belonging to this 
group assists in incubation, the domed nest allowing him to do so with 
safety. It is necessary now briefly to notice those 
Birds which do not hatch their own eggs.—The birds that come 
into this division may be divided into two groups: of one our Common 
Cuckoo (Cuculus canorus) is a good example, and the other contains 
the Megapodes (Megapodidz) or Mound-birds of the Australian Region. 
The former group will be more fully discussed in the article on the Cuckoo ; 
and of the latter so little is known that to Gould’s and Hume’s interesting 
descriptions little more can be added. It is a wonderful instinct for a 
bird to bury its eggs in the sand or amongst decaying vegetable matter, 
and leave them to be hatched by the heat of the sun or the warmth 
generated by putrefaction. The young, when hatched, are said to break 
out of their prison and to be able to take care of themselves almost directly 
afterwards. May not this singular habit, which so closely resembles the 
mode of propagation of the Turtles and Snakes, be an unchanged inheritance 
from some semi-reptilian ancestor?* Let us now glance briefly at 
Birds’ Nests.—These structures have long been regarded as one of the 
most convincing proofs of an instinctive power, a power which is popularly 
supposed to be almost supernatural, of spontaneous origin, and nearly 
infallible. Such a belief, as Mr. Wallace very justly remarks, one would 
naturally expect to find supported by incontestable facts ; but little or 
nothing can be brought forward in its favour, and the evidence in support 
* Lizards’ eggs have been taken from these mounds by Davison (‘ Stray Feathers,’ ii. 
p- 278). 
