142 ELEMENTS OF OENITHOLOGT. 



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 nidtitating 

 membrane. 



The ear almost always opens a little below and behiad 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 " cMn " 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 

 prepeetus or fore-neck. 



Some Birds — as, e. 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 circumorbital region, or part 

 round the eyes, as in the Herons. The ordinary feathered 

 * See p. 6. 



