4 KINDS OF FEATHERS. 
and barbules, the latter wanting barbicels, knots and hooklets. The first 
two types may be found in different parts of the same feather, as in pl. 1, 
fig. 7, which is partly pennaceous, partly plumulaceous. All feathers are 
built upon one of these three plans; and, though seemingly endless in di- 
versity, may be reduced to four 
§ 5. Diererent Kiyps or Frarners. 1. Contour-feathers (penne) 
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 array of tufts, crests, 
ruffs and other ornaments of the feathered tribe ; even the imperfect bristle- 
like feathers above-mentioned belong here. Another feature is, that they 
are usually individually moved by cutaneous muscles, of which there may be 
several to each feather, passing to be inserted into the sheath of the tube, 
inside the skin, in which the stem is inserted; 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 (plumule), characterized by the plumulaceous structure throughout. 
These form a more or less complete investment of the body ; they are almost 
always hidden from view beneath the contour-feathers, like padding about 
the bases of the latter; occasionally they come to light, as in the ruff about 
a condor’s neck, and then usually occur where 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 (semipluince), which may be said to unite the characters of the 
last two, possessing the pennaceous stem of one and the plumulaceous vanes 
of the other. They stand among penne, like the plumule, 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 an after-shaft. 4. 
Filoplumes (jiloplume), 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 usually 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 hairs that birds have. 
§ 6. Pecuntar Feararers. 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 always dusted 
over with the dry, seurfy exudation or exfoliation from the follicle in which 
they grow, are called powder down-feathers. They occur in the hawk, par- 
