604: 



CHORD AT A. 



which are apteria in which no contour feathers appear (fig. 632). Since 

 the contour feathers overlap like shingles, they form a firm coat of 

 plumage beneath which the down and semiplumes form a warm coat. 



FIG. 632. FIG. 633. 



FIG. 632. Feather tracts and apteria of pigeon, dorsal view. (From Ludwig-Leunis.) 

 FIG. 633. Regions and feathers of Falco lanarius. (From Schmarda.) As, secondaries ; 



Ba< belly ; Br, breast ; Bz< rump ; D'-D'", wing coverts ; Di, gonys of bill ; EF, 



alula ; F, culmen of bill ; H, occiput ; HS, primaries ; K", throat ; L, legs ; JV, neck ; 



Sch, crown ; SF, parapterium ; St, forehead, lower tail coverts ; Sz, rectrices ; W, 



cheek; WH, cere with nostril; Zh, toes. 



Besides these covering feathers (coverts, or tectrices, fig. 633, D) there are 

 the longer feathers of the wing, the remiges, and the tail feathers, or 

 rectrices (8z). The larger remiges form the chief part of the wing; they 

 spring from the part of the limb corresponding to the hand (carpus, 

 metacarpus, phalanges) and are known as primaries (HS), while the 

 secondaries (As), arising from the forearm, are shorter. These are over- 

 lapped at the base by the coverts (D, D', D' 1 ) and by the parapterium (SF) 



FIG. 634. Wing skeleton of stork. (From Gegenbaur.) c, c', carpalia of first row; 

 ft, humerus ; wi, fused metacarpals and carpals of second row ; p-p'\ phalanges of 

 first three fingers ; r, radius ; w, ulna. 



springing from the shoulder. A few feathers arising from the first finger 

 remain distinct from the remiges and form the alula (EF). In the water 

 birds especially the feathers are oiled by the secretion of a pair of glarrds 

 at the base of the tail above the coccyx. 



Since the feathers are not only for protection, but give to most 

 birds the power ol prolonged flight, they predicate a special mode 



