254 Mr W. MacgilUvray o?i the Covering of Birds. 



The plumage, then, is the general covering of a bird, which 

 usually invests all its parts, excepting the beak, eyes, tarsi, and 

 toes. It consists of a great number of individual parts, which 

 are (XenoxmnsiieA feathers. Besides these parts, however, so de- 

 nominated, there are in most birds others, which, lying conceal- 

 ed among the former, and not making their appearance at the 

 surface, are apt to be overlooked by superficial observers. These 

 are the down-feathers, and hairs, or piliform feathers, which will 

 be described in course, but which, for the sake of simplification, 

 may be for the present overlooked. These individual parts or 

 feathers are disposed upon the skin in what is called quincuncial 

 order ; that is, in lines intersecting each other at acute angles, 

 and in such a manner as to lie over each other, like the tiles on 

 the roof of a house ; a circumstance denoted in Zoology as 

 well as in Botany, by the term imbrication, their general direc- 

 tion being backwards, or from the head of the bird to the tail 

 and extremities. 



The plumage, as has just been observed, does not cover the 

 whole surface of a bird ; but, besides the parts mentioned, as 

 being altogether bare, there are others, which, although covered 

 over by the feathers, yet do not give origin to them, and are 

 thus, in a particular sense, bare. These parts are : a line from 

 the base of the upper mandible to the eye, called the lore or bri- 

 dle ; a line from the ear to the shoulder, on either side of the 

 neck ; a broader line from the fore-part of the sternum to the 

 vent ; a space upon the sides under the wings ; and in female 

 birds, and frequently in males also, during incubation, two cir- 

 cular spaces, or one transversely oblong space, of greater or less 

 size, upon the abdomen. Other parts also occur in particular 

 species or genera, which will become the subject of distinct con- 

 sideration in their own place. 



A feather may be defined an individual constituent of the 

 plumage, having a distinct existence of its own, and by its asso- 

 ciation with others contrirbuting to form the general envelope. 

 Or, in another sense, it may be defined, a mass of indurated ge- 

 latinous matter, inserted by one extremity into the skin, con- 

 nected by apposition in the greater part of its form with others, 

 and in a portion of one of its terminal surfaces touching the air, 

 having a root or proximal part of a tubular form, continued in- 



