202 A HISTORY OF BIRDS 



related may lay very similar eggs. Not only indeed do nearly 

 allied species lay eggs of widely different coloration, but instances 

 are numerous where differences no less striking obtain between 

 eggs of the same species, of which the Guillemot affords one of 

 the most striking and familiar instances. And much the same 

 is true of the shapes of eggs. Nevertheless, there are not want- 

 ing Ornithologists who, in the face of these facts, employ the 

 coloration, or lack of it, as a factor in classification ! 



Contradictory though it may seem, it is yet true, however, 

 that in broad outline we may distinguish the eggs of the larger 

 groups, though, as might be expected, exceptions are fre- 

 quent. 



Thus, for example, the eggs of the Tinamous are distinguished 

 by their extraordinary burnished appearance, met with nowhere 

 else, except in one or two isolated cases among the Passeres {Bur- 

 nesia), but from which they can of course readily be distinguished 

 by their size. Among the Petrels, such eggs as are coloured have 

 the pigment deposited in the form of a cap, or of a zone around 

 the larger end, though this peculiar distribution is not confined 

 to the eggs of this group. Among' the Steganopodes the Tropic- 

 birds lay richly coloured eggs, those of the remaining families 

 are more or less thickly incrusted with a white chalky deposit 

 concealing, as in the Cormorants and Gannets, a shell of a beauti- 

 ful blue colour. The Anserine birds, without exception, lay 

 whole-coloured, unspotted eggs ; and so also do the Stork tribe, 

 whose eggs are generally blue or green in colour, though in some 

 cases, as in the Ibises and Flamingoes, they are white and chalk 

 incrusted. The eggs of the birds of prey are either wholly 

 white, or have a ground colour of white, bluish-white or cream 

 colour, spotted with red of various shades, and purplish pigment 

 being distributed in the form of blotches varying in number and 

 intensity, so that the colour ranges from a pale rust-red to a 

 rich sienna-red, or inky purple, the blotches being sometimes so 

 thickly clustered as to entirely suppress the paler ground colour. 

 Thus the eggs of birds of this group are often of rare beauty. 

 They also exhibit a marvellous range of variabilitj' in the 

 matter of coloration, those of the Indian Kite {Mtlvtis govinda), 

 for example, in this respect are said by Mr. Hume, whose 

 authority is great, to defy description. While the Game-birds, 

 as a rule, lay whole-coloured eggs, generally cream or buff 



