Adaptation in Parasitic Cuckoos' Eggs. 391 



of two distinct types — one pure white, or, in the rarest o£ 

 instances, extremely faintly marked with pink specks, and 

 the other in colour ranging between a bright terracotta-red 

 and deep chocolate. 



The foster-parents of the white type are generally Warblers 

 of the genera PhyUoscopus, Acanthopneuste, and Cryptulojihay 

 all of which lay white eggs, but the white type has also been 

 taken on one occasion from the nest of Lojjhophanes. 



The fosterers of the red type are birds of the genus 

 Horornis, Prinia Jiaviveniiis, Oligura castaneicoronata, and 

 Tesia cyaniventris, which themselves lay red eggs, but red 

 eggs have also been taken in the nests of Stachyridopsis, 

 Dymochares cruralis, Niltava, Cyornis, Frathicola, Orthotoiaus, 

 and Tribura. 



In the vast majority of cases in India, however, Ave find 

 that the dark eggs are placed in the nests of some species 

 of Horornis, whilst further east, in Japan, they are almost 

 invariably placed in the nest of Cettia cantans ; in fact, 

 Mr. Allan Owston, from whom I procured a fine series of 

 these eggs, tells me that he has never found them in any 

 other nest. Mr. S. Whymper certainly found a very deeply 

 coloured red egg of this bird in the nest of Phylloscopus 

 affinis, but Horornis pallidus was very common in the vicinity, 

 and doubtless a bird of this species should really have been 

 the fosterer selected. 



I have also had eggs sent me by dealers and others as 

 being specimens of this Cuckoo's eggs, but they not only 

 do not agree in coloration — which in eggs of the CuculiddR 

 is of no importance — but they do not agree in size, shape, 

 or texture, and, so far, there is no evidence to show that the 

 eggs of any one of the many species of Cuckoo vary in these 

 respects. 



Penthoceryx sonnerati. — -Of this bird there is but one 

 oviduct e^^ in existence, so far as I am aware, and this is 

 in the collection of Mr, J. Davidson. I have, however, 

 a considerable series of eggs which very closely resemble 

 this oviduct egg and which certainly are Cuckoos' eggs, 

 and which, by the process of elimination, can be fairly 



SER. X. VOL. I. 2 E 



