3°° 



BIRDS. 



from certain well-defined tracts, between which are bare spaces. Although such 

 tracts have received distinct names, and are of some importance in classification, it 

 will suffice to mention their mere existence ; and we pass on to the consideration of 

 the names applied to the feathers of the tail and wings. 



As shown in the diagram on p. 298, the tail-feathers, which are very generally 

 twelve in number, are termed rectrices ; and are usually firm and fully developed. 

 Above and below the rectrices are the upper and under tail-coverts; although 

 generally small and unimportant, in the peacock the upper tail - coverts attain 

 an extraordinary development, and constitute what is commonly designated 

 the tail. Premising that the feathers clothing the shoulders are termed 

 scapulars, and those between them interscapulars, we pass on to the consideration 

 of the feathers of the wings. First of all, we have the little group of feathers 

 forming the bastard-wing, or alula, which are carried by the first digit, or thumb, 

 and lie on the front border of the back of the wing. Next, we have the flight- 

 feathers, remiges, or quills, which arise from the bones of the arm and pinion 

 (or hand, exclusive of the thumb) ; all are strong, firm feathers, giving rise to the 

 main contour of the wing. Such of the remiges as take their origin from the 

 pinion are termed primaries; while those attached to the fore-arm (ulna) and 

 upper arm (humerus) are entitled secondaries, though the remiges arising from 

 the humerus used to be distinguished as tertiaries, and the term secondaries con- 

 fined to those attached to the ulna. The primaries are the firmest and stiffest 

 of the wing-feathers, and are very generally either nine or ten in number. 

 As the rectrices of the tail have tail-coverts, so the remiges have wing- 

 coverts, both above and below. Of the upper wing-coverts, we have first the 

 primary coverts overlying the primaries ; while the secondaries are overlain 

 by three series, respectively known as the greater, median, and lesser upper 

 secondary wing - coverts. Of these the greater coverts are the largest and 

 the most important in classification. The under wing-coverts, which are less 

 important in classification, are likewise divided into a primary and secondary 

 series. 



Change of When first hatched, Birds are covered with some kind of down, 



Plumage. vei y scan ty i n those which are reared in nests, but thick in all 

 those able to run about at the time of birth. The true feathers are, however, soon 

 developed, those of the wings and tail being usually the first to make their appear- 

 ance, and the rapidity with which feathers grow is one of the most remarkable 

 features of Birds. In order to preserve the plumage in good condition, it is 

 essential that it should be renewed at least once a year. This rene%val of the 

 feathers is termed moulting, and frequently takes place twice during the year; 

 while in the ptarmigan there are three moults. The chief moult usually takes 

 place soon after the breeding-season ; but in those birds which, like ducks, have 

 a special breeding-plumage, a second moult takes place previous to that period. 

 In the ptarmigan the third moult is for the assumption of the white winter dress. 

 Usually the wing-feathers are shed in pairs one after another; but among the 

 ducks, which are enabled to conceal themselves among water plants, and can thus 

 protect themselves without flight, the shedding of all the wing-feathers is 

 frequently almost simultaneous. 



