Vol. xlii.] 108 



in the Garhwal Hills, but here Jlorornis fortipes was common, 

 and undoubtedly that bird's nest should have been the 

 recipient of this egg. In Darjeeling white eggs have been 

 taken in the nests of Oligura and red eggs in the nests of 

 Drymocharp.s cruralis which lays white eggs, but the domi- 

 nant fact remains that East and West you have two different 

 types, red and white, which both agree almost perfectly 

 with the eggs of the fosterer selected, whilst in the centre of 

 the habitat of this Cuckoo you have the two types over- 

 lapping. 



With Hierococcyx sparveroides the conditions are rather 

 different. The olive-brown type of egg (Box No. 26) is 

 apparently found only in the Hills of Assam south of the 

 Brahmapootra, whilst the blue egg is found west to the 

 Western Himalayas, and again east to Yunnan and the 

 Hills of Central Burma. It would appear as if the reason 

 for this was the fact that in these hills the original Cuckoos 

 of. this species selected nests of Araclmothera magna and 

 DrymocTiares nejmlensis, both birds which lay olive-brown 

 eggs, and so by degrees all other types of eggs have l)een 

 gradually eliminated, except a few blue egg-laying Cuckoos 

 which encroach from time to time from North, West, or 

 East. The blue type of egg, which is obtained in the 

 greatest numbers in North-East Burma, is nearly always laid 

 in the nests of those species of Garrulax which lay blue 

 eggs, the only normal exceptions hem gAIyiophoneus temmincki, 

 a large Thrush which lays eggs exactly like those of the 

 English Blackbird, but larger and paler. Possibly because 

 the two brown egg-laying fosterers are not nearly as common 

 as the blue egg-laying ones are, we find comparatively a 

 large number of abnormal fosterers accepted by this species 

 of Cuckoo. 



I have so far given examples of more or less completed 

 evolution, in the first place resulting in a single type of egg, 

 in the second in two perfectly different types. If we turn 

 to the eggs of the birds of the genus Cacomantis we find 

 yet a third phase of evolution. The normal eggs of these little 

 Cuckoos are shown in Boxes No. 23 and 24 and may be culled 



