894 Mr. E. C. Stuart Baker on the Evolution of 



leave ouly tliose survivors avIio have been most successful iu 

 laying eggs of an appropriate colour. 



The Small Hawk-Cuckoo {H. nisicolor), which lays long 

 elliptical eggs of various shades of olive-brown, more or less 

 mottled or spotted with reddish, has a rather wide range 

 of fosterers; but the majority of these will be found to lay 

 eggs of a very indefinite kind of colour, such as olive-brown, 

 olive, reddish brown, etc., with which the Cuckoo's own eggs 

 very closely agree. Eggs have been taken from the nests of 

 Staclnjridopsis rufifrons, Arachnothera longirustris, Turdinulus, 

 Pellorneum mundellii, Alcippe, and Drymocataphus, but the 

 favourite fosterers are Flycatchers of the Niltava and 

 Cyorrm groups, more especially the latter. 



HierocuccAjx varius lays plain, rather dark, blue eggs, which 

 correspond more closely, perhaps, to those of the ordinary 

 fosterer than do those of any other Cuckoo, and its eggs may 

 be found in the nests of almost every member of the genera 

 Argya and Ci'ateropus. It is very hard to distinguish the 

 Cuckoo's egg from the eggs of these Babblers, so closely do 

 they resemble one another in size, shape, and colour, and 

 even in texture the Cuckoo's egg is not nearly so well differ- 

 entiated as is generally the case. It is only when one gets 

 well outside the ordinary breeding-limits of this Hawk- 

 Cuckoo that one finds it placing its eggs in nests other than 

 those mentioned : thus in the Khasia Hills, low down near 

 Sylhet and Kamroop, I have taken a few eggs in the 

 nests of Garrulax moniliger, one or two in the nests of 

 Trochalopterum chrysojjterum, Actinodura khasiana, and a 

 single egg from the nest of Niltava macgrigorice. With this 

 last exception and one other egg sent to me from Travancore, 

 which Avas taken in the nest of Irena puella, all have been 

 placed iu nests of birds laying blue eggs, with which the 

 Cuckoos' eggs agree very well. 



Hierococcyx sparveroides, the third species of Indian Hawk- 

 Cuckoo, lays two kinds of eggs : the first and most common 

 kind is a richly coloured olive-brown egg which is almost 

 invariably laid in the nest of Arachnothera magna, a Spider- 

 Hunter which itself lays an egg of the same colour, shape, 



