206 The Bird 
sense of smell most acutely developed, although in both 
cases it is the delicate nerves of touch in the bill which 
are most helpful in detecting the presence of the earth- 
worms which constitute the food of these birds. 
To whatever degree the nostrils of land birds aid 
their owners in procuring food, it is certain that those 
Fic. 150.—Head of Apteryx, showing tactile hair-like feathers, nostrils at tip 
of beak, and small eyes. 
species which feed entirely on fish, which they swallow 
whole, have little use for nostrils, except for breathing. 
Thus Nature, ever on the watch to economize, has re- 
duced these organs, in such birds as pelicans and cor- 
morants, and, at least in the adults, the nostrils are com- 
pletely filled up with bone and horn. 
