PTILOSIS OF THE HEAD. : 21 
(ce). No part of the body has so variable a ptilosis ({ 9) as the head. In 
the vast majority of birds, it is wholly and densely feathered; it ranges 
from this to wholly naked; but nakedness, it should be observed, means 
only absence of perfect feathers, for most birds with unfeathered heads have 
a hair-like growth on the skin. Our samples of naked headed birds, are the 
turkey, the vultures, the cranes, and some few birds of the heron tribe. 
Associated with more or less complete “baldness,” is frequently the presence 
of various fleshy outgrowths, as combs, wattles, caruncles (warty excres- 
cences), lobes and flaps of all sorts, even to enumerate which would exceed 
our limits. The parts of the barn-yard cock exemplify the whole; among 
North American birds they are very rare, being confined, in evident devel- 
opment at any rate, to the wild turkey. Sometimes horny plates take the 
place of feathers on part of the head; as in the coots and gallinules. A 
very common form of head nakedness marks one whole order of birds, the 
Steganopodes, which have mentum and more or less of gula naked, and 
transformed into a sort of pouch, extremely developed in the pelicans, 
and well seen in the cormorants. The next commonest is definite bareness 
of the lores, as in all herons and grebes. A little orbital space is bare in 
many birds, as the vulturine hawks, and some pigeons. Among water birds 
particularly more or less of the interramal space is almost always unfeath- 
ered; the nakedness always proceeds from before backwards. With the 
rare exceptions of a narrow frontal line, and a little space about the angle of 
the mouth, no other special parts of the head than those above given are 
naked in any North American bird, unless associated with general baldness. 
(f). The opposite condition, that of redundant feathering, gives rise to all 
the various crests (L., pl. criste) that form such striking ornaments of many 
birds. Crests proper belong to the top of the head, but may be also held 
to include those growths on its side; these together being called crests in 
distinction to the ruffs, rufiles, beard, ete., of gula or mentum. Crests may 
be divided into two kinds:—1, where the feathers are simply lengthened 
or otherwise enlarged, and 2, where the texture, and sometimes even the 
structure (§ 4) is altered. Nearly all birds possess the power of moving 
and elevating the feathers on the head, simulating a slight crest in moments 
of excitement. The general form of a crest is a full soft elongation of the 
coronal feathers collectively; when perfect such a crest is globular, as in 
the Pyrocephalus (genus 111) ; generally, however, the feathers lengthen on 
white; or by unmarked change of a secondary color, as green into blue or yellow. (2) by obvious markings. 
Markings are all reducible to two kinds, streaking and spotting. Streaking, as a generic term, is sharply 
divisible into lengthwise and crosswise. Lengthwise streaking comprehends all kinds of streaks, stripes, vitte, 
fascix, with the distinctions above given in the text. Crosswise streaking is called barring, and always runs 
transverse to the axis of a bird; if the lines are straight, it is banding; if undulating, it is waving; if very 
fine and irregular, it is vermiculation (L. vermiculus, a little worm). Spotting is graded according to size 
of the markings, from dotting or pointing, to blotching or splashing; and spots are also designated accord- 
ing to their shape, as round, square, U-shaped, V-shaped, hastate, sagittate, ete. Very fine spotting mixed 
with streaking, is called marbling; when indistinct, nebulation or clouding; intermediate special marks have 
particular names, as crescents. Distinct round spots are ocelli (‘‘little eyes”). Indistinct variegations of any 
sort are called obsolete. Washes of color over a definite color, are called tinges or tints. Color is glossy when 
it shines; metallic, when it glitters; iridescent when it changes with different lights. Colors are also bright 
dull, dead (said of white), opaque, or velvety (said of deep colors, chiefly black), ete. 
