142 , ELEMENTS OF ORNITHOLOGY. 
The eyes are generally placed at the side of the head towards 
its middle, but may be placed further back, as in the Wood- 
cock; or anteriorly situated, looking forwards, as in the Owls. 
Each eye has an upper and a lower eyelid, and there is also a 
third eyelid (a rudiment of which exists at the inner angle of our 
eye) which sweeps obliquely over the eyeball within the other 
eyelids. If the eye of an Owl or Hawk be watched, this will 
be seen as a pearly-white film rapidly appearing and disappear- 
ing as it covers and uncovers the eye. It is called the wictitating 
membrane. : 
The car almost always opens a little below and behind the 
eye, but may do so below it, as in the Woodcock. It is hidden, 
and only indicated by a difference of texture in the feathers 
(auriculars) which cover them. Occasionally this opening is 
provided with a flap, which can close it, as in some Owls. 
The nose is always made up of a pair of nostrils, though these 
may open above like one tube, as in the Petrels. The nostrils 
open externally on the bill in different situations in different 
birds,—as may be more conveniently indicated in describing the 
bill. Internally they open into the back of the mouth, some- 
times by one aperture, but generally by two. 
The part of the side of the head between the eye and the base 
of the upper mandible is termed the “ lore;” and the cheek is 
behind and below it in a line with the lower mandible. At the 
lower margin of the cheek is a narrow, linear space known as 
the malar region. 
The “chin” or mentum is the part (feathered or bare) on the 
underside of the lower mandible behind the point of junction 
of its two lateral halves or rami. This is also called the 
interramal space. Below the chin is the gular region or throat, 
followed by the jugulum or lower throat, to which succeeds the 
prepectus or fore-neck. 
Some Birds—as, ¢. g., Turkeys and Vultures—have naked 
heads. That is, they have only filoplumes instead of ordinary 
feathers on their heads. Such Birds often possess (as also 
do various, others) some other kind of warty or fleshy out- 
growth called ‘‘lobes” or ‘ wattles,” ‘combs,’ ‘ ? 


caruncles,” or 
“ horns,’ such as those of the Tragopans*, as the case may be. 
The gular region may be naked as in the Pelican’s pouch, or 
the lores as in Grebes, or the cirewmorbital region, or part 
round the eyes, as in the Herons. The ordinary feathered 
* See p. 6. 
