APPENDICES 
433 
dusk one sees the whole crowd “ full-up ” and all beaks 
agape. 
No single section of animate Nature in the Sudan more 
demonstratively illustrates the working of that principle, “The 
Influence of Environment,” than do the denizens of the Desert. 
Already in the chapters descriptive of the deserts are given 
instances of wondrous assimilation between living creatures 
and their inanimate surroundings—the desert-larks, for example 
( Certhilauda , Pyrrhulauda , and Amommanes ). None of them, 
Finch-Larks ( Pyrrhulauda ). 
Cinderella of the desert.” “ The proud beauty of the corn-lands,” 
however, recognise a protective value in their own coloration, or 
attempt to exploit the quality as a personal safeguard. The 
black-headed finch-lark ( Pyrrhulauda ) is a typical illustration. 
On the rich cotton-soil this bird is richly arrayed in warm 
chestnut and black; on the littoral barrens in neutral grey. 
But on the open desert — though colour -patterns remain 
identical — every vestige of a positive hue has vanished, 
replaced by merely milky apologies for colour, faded and 
washed-out in consonance with the surrounding Sahara. 
One character, however, all three types retain — the proud 
beauty of the corn-lands and the faded Cinderella of the 
desert alike. All are jet-black on under-surfaces and heads ; 
2 E 
