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



The measurements are as follows : — Length of the male 

 averaging 7*25 in., of the female 7*10 in. ; culmen 0*5 in. ; 

 wing 2'5 in. ; tarsus 0'7 in. ; tail in male 3*7 in., and in 

 female 3*3 in. Bill black, legs brown, irides brown. 



It remains to make some remark as to the distribution 

 of these three species : Pericrocotus stanfordi, P. roseus, and 

 P. cantonensis. P. stanfordi is found at Samshui, and thence 

 as far west as Tak Hing, where it is replaced by P. roseus. 

 Both these species are migratory, and both breed in their 

 respective areas. P. roseus, which has not been noticed from 

 China before, probably occurs through Kwang Si and 

 Yunnan on into India. 



Pericrocotus cantonensis was only met with once upon the 

 North River, and is, in the writer's opinion, an accidental 

 visitor to the region dealt with in this article. The range of 

 P. cantonensis is further to the east and north — so far as is 

 known — than that of the other two species. 



What has been written as to habits and nidification under 

 the head of P. ruseus, applies equally well to ]'. stanfordi. 



]t has been suggested that P. stanfordi is a hybrid between 

 P. roseus and P. cantonensis. 



The type of P. stanfordi is, with all the other examples 

 collected, now preserved in the Natural History Museum at 

 S. Kensington. 



XXI. — The Evolution of Adaptation in Parasitic Cuckoos^ 

 Eggs. By E. C. Stuart Baker, F.Z.S., I\I.B.O.U. 



It is still sometimes a matter for argument and discussion 

 as to whether the eggs of Parasitic Cuckoos have undergone, 

 or are noAV undergoing, any process of adaptation in shape, 

 size, or coloration, to render them similar to those of the 

 foster-parents in whose nests they are deposited. 



As regards Cuculus canorus canorus it is almost universally 

 accepted as a fact that some such process is being slowly 

 undergone, and that by it a most wonderful adaptation has 

 already been arrived at in many instances. Thus we may 



