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 inter scapulars, 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. very scanty in 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 renewal 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. 
