external ANATOMV WING FEATHERS. SI 
Wing. They consequently form three divisions, distin- 
guished as the primaries, the secondaries, and the ter- 
tials. The primaries are the outermost ; the;y are almost 
always longest, and in swift flying birds, like the swal- 
low, are double the lengtli of any of the other quills. 
The primaries are ten in number, and are attached to 
the carpus, or those bones which represent the hand ; 
they gradually diminish in length until they reach the 
secondaries, which are inserted on the cubitus, or first 
joint of the ann, and are usually only half the length 
of the primaries. Lastly come the tcriials, which have 
their origin from the humerus. M. Cuvier has wrongly 
applied the term scapular to these feathers, which are 
unquestionably a portion of the quiUs ; neither do they 
cover the scapulars, for their peculiar office is to fill up 
the interval between the body and the wing, which 
Would otherwise arise when the latter was expanded, 
and, by confining the air, to oppose a broader surface 
of resistance to it. The true scapulars consist of a 
longitudinal series of feathers very thickly crowded at 
their insertion, commencing at the axillie, or armpit of 
to unite more perfectly the 
shoulder covers with the fea- 
thers of the body. The sca- 
pulars, therefore, are the 
most convex feathers of the 
bird ; they are also much 
longer than those which they 
join, and they gradually unite 
with the tertials, which are 
equally convex, and they serve, 
when the wing is folded, to 
protect the lesser quills. The 
annexed figure (fig. 40.) 
will explain all these parts at 
once to the eye; and we may 
now proceed to notice the 
different modifications which 
wings ot birds (^that is, the quills) present. 
the wing, and intended 
