SEC. Ill EXTERIOR PARTS OF BIRDS 145 



skin. Examples of naked - headed birds are the turkey, the 

 vultures, the cranes, and some of the heron tribe, as ibises. 

 Associated with more or less complete baldness, is the frequent 

 presence of various fleshy outgrowths, as combs, wattles, caruncles, 

 lobes, and flaps of all sorts, even to enumerate which would exceed 

 our limits. The parts of the barn-yard cock exemplify the whole. 

 Sometimes horny plates take the place of feathers on part of the head ; 

 as the frontal shields of the coots and gallinules. A very common 

 form, of head-nakedness marks one whole order of birds, the Stegano- 

 podes, which have mentum and more or less of gula naked and trans- 

 formed into a sort of pouch, extremely developed in the pelicans, 

 and well seen in the cormorants. The next commonest is definite 

 bareness of the lores, as in all herons and grebes ; in the former 

 including the whole circum-orbital region. A little orbital space is 

 bare in many birds, as the vulturine hawks, and some pigeons ; 

 species of grouse have a bare warty supra-orbital space. Among 

 water birds particularly, more or less of the interramal space is 

 almost always unfeathered ; the nakedness always proceeds from 

 before backwards. 



The opposite condition, that of redundant feathering, gives rise 

 to all the various crests (Lat. pi. cristce) that form such striking 

 ornaments of many birds. Crests proper belong to the top of the 

 head, but may be also held to include those growths on its side ; 

 these together being called crests in distinction to the rufis, ruffles, 

 beard, etc., of gulla or mentum. Crests may be divided into two 

 kinds : 1, where the feathers are simply lengthened or otherwise 

 enlarged ; and 2, where the texture, and sometimes even the 

 structure, is altered. Nearly all birds possess the power of moving 

 and elevating the feathers on the head, simulating a slight crest in 

 moments of excitement. The general form of a crest is a full, soft 

 elongation of the coronal feathers collectively ; when perfect, such a 

 ■ crest is globular, as in the Neotropical genus Pyrocephalus ; generally, 

 however, the feathers lengthen on the occiput more than on the 

 vertex or front, and this gives us the simplest and commonest form. 

 Such crests, when more particularly occipital, are usually connected 

 with lengthening of nuchal feathers, and are likely to be of a thin, 

 pointed shape, as is well shown in the lapwing (Vanellus cristatus). 

 Coronal or vertical crests proper are apt to be rather different in 

 coloration than in specially marked elongation of the feathers ; they 

 are perfectly illustrated in the goldcrest, and other species of the 

 genus Begulus. Frontal crests are the most elegant of all ; they 

 generally rise as a pyramid from the forehead, as excellently 

 shown in the crested titmouse (Parus cristatus) and others. All the 

 foregoing crests are generally single, but sometimes double ; as shown 

 in the two lateral occipital tufts of the " horned " lark (Er&n 



