XXXll 
INTRODUCTION. 
Gull ; in others, round and marginated, as in the Cuckoo ; in some, oral, 
as in the Butcherbird ; and in the gallinaceous kinds, partly covered with 
a membranous valve. Small as are the nostrils of birds, and apparently 
ill adapted for a quick sense of -smelling, yet many of their races possess 
this sense in an extreme degree of delicacy. I'he Vultures wind their 
putrid prey at an immense distance, and are often seen floating slowly 
along, in multitudes, as far as the eye can extend its view, directing their 
flight with certainty to the object of their voracious appetites. And the 
Crow and the Raven, with the sense of smell inferior to that of the 
Vulture, will discover at an immense distance the carcase that allures them. 
The Wild Duck trusts more to its smell than to its sight or its hearing, and 
marks the approach of an enemy from the notices which it receives from 
the tainted gale, when its other faculties would suffer it to remain in blind 
security. The tongues of birds are no less various, some are bifid, others 
divided into many filaments, as in many of the Sparrow kind ; others are 
smooth and slender at the tip, as that of the Cuckoo ; the extremities of 
others are pointed with bristles ; others end in a stiff', horny substance, like 
that of the Woodpecker ; and the tongues of the Goatsucker and the 
Kingfisher, are exceedingly diminutive, like trunks of small trees in 
enormous caverns ; while, on the other hand, that of the Woodpecker 
with its spring-like cartilages, is of prodigious length, strengthened by two 
large muscles, tipped with a stiff, horny substance, and edged on its sides 
with firm spikes, to transfix the insects which lurk in the clefts and chasms 
in which they insert it. The heads of birds are commonly so framed as 
best to permeate the air ; they are in most of the species of a small and 
oval form ; although birds of the Owl, and some of the carnivorous kinds, 
have large heads. 
All birds yet known have two eyes ; their exterior parts are not 
so hemispherical as in men and quadrupedes, but are formed with an 
obtuse and flattened front. The flatness of the organ of vision in birds, 
is, perhaps, one of the causes of their piercing sight, as the axis is 
