238 THE VARIATION OF ANIMALS IN NATURE 



Normally the eggs are earth-coloured with dark markings, and 

 are very difficult to see on ordinary earth. But on a compara- 

 tively narrow strip along the Malabar coast, stretching into 

 Travancore, the soil is composed of a brick-red laterite with 

 dark ironstone nodules. In this region the eggs are red (pale 

 to deep buff) with dark markings, and are again almost invisible. 

 It is stated that rarely eggs of a colour unsuitable to their 

 background are laid, and these are found to be very conspicuous. 

 Stuart Baker suggests that pressure of population forced the 

 bird to nest on the red soil, and that selection by egg-eating 

 enemies has brought about the protective resemblance. 



This example is particularly interesting because any direct 

 effect of the environment appears highly improbable. It is 

 unfortunate that the nests on the boundary line between the 

 red and dark soils have not been investigated : here one would 

 expect to find more frequent cases of misfits and selection 

 might actually be seen at work. The actual destruction of 

 eggs does not yet appear to have been witnessed. There are, 

 of course, very many other birds with more or less ' protectively 

 coloured ' eggs, but there are few examples in which selective 

 elimination is so clearly suggested. 



Passerella (Fox Sparrows) (Linsdale). 



Linsdale (1928, p. 361) shows fairly clearly that the Yolly 

 Bolly Mountains race of P. iliaca tends to be brownish in accord- 

 ance with the soil in that area, which is much darker than 

 that within the range of the other races. This case is not statis- 

 tically treated ; but Linsdale is a careful and critical observer. 



Dark races o/Ammomanes (Desert Lark). 



Meinertzhagen (in Cheesman, 1926, p. 318) has described 

 a race of the Desert Lark (A. deserti annae) which is almost 

 completely black and lives on a narrow belt of black 

 ' iron-pan ' rock. On the sandy plain beyond the lava strip a 

 pale Ammomanes (A. deserti coxi) exactly imitating the colour- 

 tones of the desert replaces the dark bird. So, too, a pale form 

 occurs on the white chalky limestone hills at Hufuf. These birds 

 are apparently very restricted in their habitat (id. I.e. p. 319). 



Galerida (Desert Larks) . 



Bannerman (1927, p. 95) has carefully studied the Desert 

 Larks in relation to varying tracts of the soil on which they 



