XXX INTRODUCTION. 
and the Plovers (Charadriide), each of which great natural groups numbers 
upwards of a hundred species, which are as cosmopolitan as the Ducks ; and 
the eggs of both are so characteristic that a glance is sufficient to recognize 
them. Take, as another instance, the eggs of the great cosmopolitan family 
Laridz: those of the Gulls (Larinz) most nearly resemble those of the 
Sandpipers in colour, whilst those of the Terns (Sternine) show more 
affinity to the true Plovers ; and this may probably be accounted for by the 
nidification of each group resembling most closely that to which the eggs 
are allied in general appearance. The Game Birds are also another instance. 
So far as I know, the eggs of these birds never have any underlying mark- 
ings, all the colour is on the surface; and this is one great reason why the 
aberrant Hemipodes (Turnix) should be excluded from this group of birds, 
for their eggs possess both characters of markings, and therefore show the 
birds’ affinity to the Rails, the Plovers, or the Bustards*. Canon Tristram 
is probably right when he says that the style of architecture and coloration 
and form of the egg cast as much light on the true grouping of species 
and the arrangement of genera in the great subfamily of the Warblers 
(Sylviinze) as in any other class of birds. I think that it is even a better 
generic character than any the birds themselves are known to possess. 
This group of birds exhibits in a wonderful manner certain distinct types 
of eggs, a study of which alone will place the birds in almost the same 
position as that to which they have been assigned by the best systematists. 
Details cannot well be given here, but the remarks on this subject by 
Canon Tristram (‘ Ibis,’ 1867, p. 74) are worthy the perusal of all inter- 
ested in oology: it has been briefly noticed in the present work (vol. i. 
p. 373). The subfamily of the Thrushes (Turdine) is another remarkable 
instance, and might almost be split up into fairly natural genera by the 
coloration of the eggs alone. 
It is also very remarkable how the eggs of some birds resemble those of 
species belonging to very distantly related groups, where the conditions of 
nidification are similar; and this I think is one of the strongest proofs of 
a universal law of colour governing these objects. The Sand-Martin and 
the Woodpecker, or the Dipper and the Weaver-bird are good examples in 
which a covered nesting-site is peculiar to each and the eggs are uniformly 
white. In cases where the eggs differ considerably from those typical to 
the group, we generally find that the mode of nidification adopted by the 
species is from some cause different and aberrant too.. Take, for imstance,, 
the eggs of the American Quail (Ortyx virginianus), which are white and 
laid in a domed or covered nest, whilst those of the allied Plumed Quail 
(Lophortyx gambeli) are normally spotted and blotched, and, it is needless 
to say, laid in an open nest. 
* Conf. Hume, ‘ Nests and Eggs of Indian Birds,’ p. 554. 
