284 MR. E. C. STUART BAKER ON 



Chinese Hills I have little evidence of a sufficiently reliable 

 nature for me to say what kind of egg the bird lays, but what 

 little thei-e is would lead one to suppose it to be the same as the 

 Japanese form. In Eastern India our evidence is ample and 

 here we find that the two types overlap so that from Assam to 

 Garhwal we get both the pure white and the chocolate type but 

 the first is the common one to the West, the second the more 

 common in the East, In India, however, we have no true 

 Cettia and accordingly we find that the normal fosterers in this 

 country for the red eggs are the various species of the genus 

 Horornis, all of which lay dark chocolate eggs which go well with 

 the dark form of Cuckoo's egg. Other nests in which the Hima- 

 layan Cuckoo deposits her terra-cotta eggs are those of Tesia and 

 Oligura, both genera (if they are divisible from one another) of 

 birds which lay pink eggs not contrasting greatly with those of 

 the Cuckoo, 



It is true that with this last Cuckoo we have a great many 

 instances of both red and white eggs being placed in nests 

 containing eggs which are quite unlike their normal fosterers 

 but this is what occurs more or less with every Cuckoo. It 

 occurs least of all with those Cuckoos in which evolution has 

 proceeded farthest, most with those Cuckoos in which the 

 destruction of the unfit has only just commenced to operate. In 

 the present case, however, neither of these factors can be con- 

 sidered alone. Here we have a bird, the eggs of which in each 

 extreme of its habitat have by the process of elimination arrived 

 at one definite type, which is in every way complete in so far as 

 its local needs are concerned, whilst in the neutral country 

 between the two extremes we have both types of eggs laid and 

 consequently we obtain frequent instances of mistaken depositing. 

 Eggs so deposited are probably not hatched in many instances 

 and we shall thus, by the gradual elimination of the unfit, finally 

 get two definite types of egg laid by the same species of bird 

 within the same area, but always normally placed in its proper 

 type of foster-parents' nest. 



The next example of Cuckoo shows a further advance in this 

 direction. Hierococcyx sj)arveroides lays two types of egg which 

 contrast quite as strongly in colour as do those of Cucuhis polio- 

 cephalus and we here also have a coincident variation in the size 

 of the Cuckoos' eggs. 



This bird, the Large Hawk Cuckoo, lays two types of eggs. 

 The first is a dark olive-brown egg, varying somewhat in depth 

 of colour and in the degree of olive tint. The surface is hard 

 and glossy and the shape a very elegant, pointed oval. This egg 

 is laid in the nest of the Great Spider-Hunter, Arachnothera 

 magna and at least 20 eggs of the Cuckoo will be found in this 

 bird's nest to one elsewhere and even of these latter the great 

 majority will be taken in the nests of the Little Shortwing, 

 Heteroocenicus nipalensis. The eggs of both the Spider-Hunter 



