104 GENERAL ORNITHOLOGY. 



Among water-birds particularly, more or less of the interramal space is almost always unfeath- 

 ered ; the nakedness always proceeds from before backward. With the rare exceptions of a 

 narrow frontal line, and a little space about angle of mouth, no other special parts of the head 

 than those above given are naked in any North American bird, unless associated with general 

 baldness. 



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 

 top of head, but may be also held to include those growths on its side ; these together being 

 called crests in distinction to the ruffs, ruffles, beard, etc., of gula or mentum. Crests may be 

 divided into two kinds: 1, where feathers are simply lengthened or otherwise enlarged ; and 

 2, where texture, and sometimes even 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 ex- 

 citement. The general form of a crest is a full, soft elongation of coronal feathers collectively ; 

 when perfect, such a crest is globular, as in the genus Pyrocejjhalus ; generally, however, 

 feathers lengthen on occiput more than on 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 well shown in 

 the Kingfisher. Coronal or vertical crests proper are apt to be different rather in coloration 

 than in much elongation of feathers ; they are perfectly illustrated in the Kingbird, and other 

 species of the genus Tyrannus. Frontal crests are the most elegant of all ; they generally rise 

 as a pyramid from the forehead, as excellently shown in the Bluejay, Cardinal, Tufted Tit- 

 mouse, and others. All the foregoing crests are generally single, but sometimes double ; as 

 shown in the two lateral occipital tufts of " horned " Larks, in all tufted or " horned " Owls, 

 and in some Cormorants. Lateral crests are, of course, always double, one on each side of the 

 head; they are of various shapes, but need not be particularized here, since they mostly belong 

 to the second class of crests — those consisting of texturally modified feathers. It is a general, 

 though not exclusive, character of these last that they are temporary ; while tlie other kind is 

 only changed with the general moult, these are assumed for a short period only, the breeding 

 season ; and they are often distinctive of sex. Occurring on top of head, they furnish remark- 

 able ornaments of birds. I need only instance the elegant helmet-like plumes of Partridges of 

 the genus Lophortyx ; the graceful flowing train of Oreortyx picta ; the similar plumes of 

 Night and other Herons. Most Cormorants and some Auks possess lateral plumes of similar 

 description ; these, and those of Herons, are usually deciduous ; while those of the Partridges 

 above mentioned last as long as the general plumage. In many birds, especially Grebes, these 

 lateral plumes are associated or coalesce with ruffs, which are singular lengthening and modi- 

 fying of feathers of auriculars, gente and gula ; and are almost always temporary. Beards, or 

 special lengthening of mental feathers alone, are comparatively rare ; we have no good exam- 

 ple among our birds, but a European vulture, Gypaetus harbatiis, is one. The feathers some- 

 times become scaly (squamous), forming, for instance, the exquisite gorgelets or frontlets of 

 Hummingbirds. They are often bristly (setaceous), as about the lores of nearly all Hawks, 

 the forehead of the Dabchicks, Meadow-larks, etc. A particular set of bi'istles, which grow in 

 single series along the gape or rictus of many birds, are called rictal bristles or vibrissa. These 

 are more or less developed in nearly all small insectivorous birds; they are large, stiff, and 

 highly characteristic ot the family Tyrannidce, or Tyrant Flycatchers ; while in some of 

 Goatsuckers (Caprimulgidce) they are prodigiously long, and in one species of that family 

 (Antrostomus caroUnensis) have lateral filaments. While usually all unlengthened head- 

 feathers point backward, they are sometimes erect, forming a velvety pile, or they may radiate 

 from a given point, as from the eye in most Owls, where they form a disc. 



In the foregoing paragraph I mention only a few styles of crests, chiefly needed to be 

 known in the study of our native birds; there are many others, with endless modifications, 



