432 



Vertehrata. 



barbs) J and furnislied with relatively short barbules^ of which, those 

 on the anterior row, lie obliquely above the posterior row of the 

 preceding barb. Further, each barbule of the anterior row is 

 provided with a series of delicate hair-like microscopic appendages, 

 some of which are curved at their tips, to hook into the hinder row of 

 the preceding barb; by means of these booklets, the barbs are 

 attached together into a continuous lamina. In the proximal 



Pig 358. 



Pig. 359. 



Pig. 358. Diagrams of various feathers to elucidate the varied development of the 

 aftershaft; vane only in outline. — Orig. 



Pig. 359. A Down of a young Bird, resting upon the tip of the succeeding feather which 

 is still surrounded by a horny sheath (k). s quill of the down feather. B tip of a contoiur 

 feather with some down barbs still attached. Diagrammatic. — Orig. 



portion of the vane, the barbs are softer and thinner, the barbules 

 long and soft, but without hooks ; this portion, which is covered by 

 other feathers, has thus a soft, loose, downy character. At the 

 junction of quill and shaft, there usually arises from the inner side 

 of the feather, a smaller, thinner shaft (the aftershaft), which 

 bears a double row of soft barbs ; the after shaft and its barbs may 

 be termed the accessory vane. - This appendage is sometimes well- 

 developed (e.g., Fowls, Fig. 358 A) ; usually, however, it is somewhat 

 feeble [B) ; its sha,ft is often rudimentary, so that the accessory 

 vane is only represented by a tuft of barbs arising close together (C) . 

 Of the contour feathers, the flight and steering feathers 

 {remiges, rectrices) must be noticed, the strongest, stifEest, usually 



