146 GENERAL ORNITHOLOGY 



aljjestris), in all the " horned " owls, and in a few cormorants. Lateral 

 crests are always double, one on each side of the head ; they 

 are of various shapes, but need not be particularised here, especially 

 since they mostly belong to the second class of crests, — those con- 

 sisting of texturally modified feathers. It is a general, though not 

 exclusive, character of these last that they are temporary ; while the 

 other kind is only changed with the general moult, these are assumed 

 for a short period only, the breeding season ; and, furthermore, they 

 are often distinctive of sex. Occurring on the top of the head, they 

 furnish the most remarkable ornaments of birds. I need only 

 instance the elegant helmet-like plumes of the partridges of the 

 genus Lophorfi/x ; the graceful flowing train of Oreortyx ; the some- 

 what similar plumes of the night-herons. The majority of the 

 cormorants, and many of the auks, possess lateral plumes of similar 

 description ; these, and those of the herons, are probablj' — in most 

 cases certainly — deciduous; while those of the partridges above 

 mentioned last as long as the general plumage. These lateral 

 plumes, in many birds, especially among grebes, are associated Avith, 

 and, in fact, coalesce with, the rufts, which are singular lengthening 

 and modifying in different ways of feathers of auriculars, gense, and 

 gula ; and are almost always temporary. Beards, or sjDecial lengthen- 

 ing of the mental feathers alone, are comparatively rare ; a European 

 vulture, Gypaet'us harbatus, is a good example. The feathers some- 

 times become scaly (squamous), forming, for instance, the exquisite 

 gorgelets or frontlets of humming-birds. They are often bristly 

 [setaceous), as about the lores of nearly all hawks. A particular set 

 of bristles, which grow in single series along the gape of many birds, 

 are called rictal bristles or mbrissce. These occur in greater or less 

 development in most small insectivorous birds ; they are large and 

 stiff" and highly characteristic of the family Muscicapiche or flycatchers; 

 while in some of the goatsuckers {Caprirnulgidce) they are pro- 

 digiously long, and in one species of that family (Antrostomus 

 carolinensis) they have lateral filaments. While usually all the un- 

 lengthened head-feathers jDoint backward, they are sometimes erect 

 forming a velvety pile, or they may radiate in a circle from a given 

 point, as from the eye in most owls, where they form a facial disk. 



Of the Members : their Parts and Organs 



I. THE BILL 



The Bill (Lat. rostrum) is hand and mouth in one : the instru- 

 ment of prehension. As hand, it takes, holds, and carries food or 

 other substances, and in many instances feels ; as mouth, it tears, 

 cuts, or crushes, according to the nature of the substances taken ; 



