The Senses 205 
In all animals the mucous membrane which lines the 
nasal cavity is very delicate and filled with nervelets. 
These nervelets unite and form a single nerve on each 
side which passes to the brain and transmits the impres- 
sions derived from the odours in the air. The thin bones 
within the nostril, which, in dogs and deer, curl and re- 
curl in delicate lines and 
scrolls and thus expose 
such a large surface to 
the odour-bearing air, are 
but poorly represented in 
birds. The simple curve 
of the bone in the nos- 
trils of birds is very simi- 
lar in structure to that 
found in reptiles. 
The question whether 
vultures. perceive their’ 9.2444 —ayetinal sevlls of doe. Ine 
prey by sight or smell has Pid these bones are far more simple. 
been decided in favour of the former sense. Lacking the 
ability readily to distinguish delicate odours, we find 
among birds none of the glands which are so common 
among hairy-coated creatures: the oil-gland is the only 
one on the body, and this is practically odourless. But 
slight as is the scent which diffuses from birds, it is 
sufficient to enable a dog, with his wonderful keenness 
of smell, to detect a crouching bird some distance 
away. 
The woodcock of our inland swamps and marshes, 
and the apteryx of New Zealand, probably have the 
