314 Letters, Extracts, and Notes. [Ibis^ 



speaking, is a brilliant blue egg to an equally brilliant pink 

 one. The reasons for this transition are not obvious. It is 

 true that the red eggs occur in the wettest climate, and 

 that the birds laying them often breed in grass lands in, or 

 surrounded by, swamps. On the other hand, as the range 

 works north from Ceylon to Assam and thence again east 

 and south to Siam, we pass through areas of considerable 

 drought and yet find no corresponding change in the colour. 



" The next lot of boxes contains series of eggs of another 

 species of Warbler, the subspecies of which range over the 

 same area as the hist, but whereas the various races of 

 Prinia inornata lay eggs which vary little in any given area, 

 this bird- {Orthotomus svtorius) lays eggs — as may be seen 

 from the exhibit — which vary immensely throughout each 

 portion of the whole of its range. But an examination of 

 the exhibit will show that Orthotomus sutorius sutorius, 

 0. s. atriyuluris (possibly a different species), O. s. muculi- 

 collis, and O. rujiceps lay eggs which, however greatly they 

 vary irder se, cannot be assigned to any one species or sub- 

 species by an inspection of the eggs alone. As a contrast 

 to the extreme variation in type in the eggs of Orthotomus 

 I show here boxes containing eggs of (1) Warblers of the 

 Prinia jiavirostns group, and (2) Warblers of the Horornis 

 group, which show how singularly uniform the eggs of 

 these two groups are throughout their whole range, the first- 

 named always laying brick-red eggs, and the second equally 

 constantly chocolate-coloured ones. 



"A rather interesting contrast in the eggs of closely allied 

 genera is shown in the two succeeding boxes. In the first 

 are the entirely white eggs of various species of Crypto- 

 lopha, and in the next the well-spotted pinkish eggs of 

 the genus Abrornis. These two genera are linked together 

 by some of our best ornithologists ; but their habits widely 

 differ, and, as every one knows, the former make lovely 

 moss-balls of nests which they line with thistle-down and 

 place in mossy banks or on moss- and fern-covered stumps, 

 whereas the latter lay their eggs in hollow bamboos or tiny 

 holes in stuujps on pads of feathers, moss, and vegetable- 

 down. One clutch of eggs, that of Abrornis sckisticeps, now 



