4 KINDS or FEATHERS. 



and barbules, the latter wanting barbicels, knots and booklets. The first 

 two types may be found in different parts of the same feather, as in pi. i, 

 fig. 7, which is partly pennaceous, partly plumnlaceous. All feathers are 

 built upon one of these three plans ; and, though seemingly endless in di- 

 versity, may be reduced to four 



§ .5. Different Kinds of Feathers. 1. Contour-feathers (pennce) 

 have a perfect stem composed of barrel or shaft, and vanes of pennaceous 

 structure at least in part, usually with downy structure toward the base. 

 They form the great bulk of the plumage, that is upon the surface of a bird, 

 exposed to light ; their tints give the bird's colors ; they are the most vari- 

 ously modified of all, from the fishlike scales of the penguin, to the glit- 

 tering plates of the humming-bird, and all the endless arraj^ of tufts, crests, 

 ruffs and other ornaments of the feathered tribe ; even the imperfect l)ristle- 

 like feathers above-mentioned belong here. Another feature is, that they 

 are usually individually moved hy cutaneous muscles, of which there maj^ be 

 several to each feather, passing to be inserted into the sheath of the tube, 

 inside the skin, in which the stem is iusertcd ; it is estimated that some 

 birds have twelve thousand of these little feather muscles. Every one 

 has seen their operation when a hen shakes herself after a sand-bath ; and 

 any one may see them plainly under the skin of a goose. 2. Down-feath- 

 ers {plunmloi) , characterized by the plumnlaceous structure throughout. 

 These form a more or less complete investment of the l)ody ; they are almost 

 always hidden from view beneath the contour-feathers, like padding about 

 the bases of the latter ; occasionally thej^ come to light, as in the ruff about 

 a condor's neck, and then usually occur whore there are no other feathers ; 

 they have an after-shaft or none, and sometimes no rhachis at all, when the 

 barbs are sessile in a tuft on the end of the barrel. They often, but not 

 always, stand in a regular quincunx between four contour-feathers. 3. The 

 semiplumes (^semijolumce) , Avhich may be said to unite the characters of the- 

 last two, possessing the pennaceous stem of one and the plumnlaceous vanes 

 of the other. They stand among penna3, like the plumulte, about the edges 

 of patches of the former, or in parcels by themselves, but are always cov- 

 ered over by contour-feathers. They are with or without au after-shaft. 4. 

 Filoplumes {filophtmoi) , or thread-feathers ; these have an extremely slen- 

 der, almost invisible, stem, not well distinguished into barrel and shaft, and 

 no vanes (with rare exceptions), unless a few barbs near the end of the 

 rhachis may be held for such. Long as they are, they are usualty hidden 

 by the contour-feathers, close to which they stand as accessories, one or 

 more seeming to issue out of the very sac in which the larger feathers are 

 implanted. They are the nearest approach to JiaiJ-s that birds have. 



§ 6. Peculiar Feathers. Certain down-feathers are remarkable for 

 continuing to grow indefinitely, and with this growth there is constant break- 

 ing off of the ends of the barbs. These feathers, from being alwaj^s dusted 

 over with the dry, scurfy exudation or exfoliation from the follicle in which 

 they grow, are called powder doxvn-feathers. They occur in the hawk, par- 



