100 GENERAL ORNITHOLOGY. 
a velvety pile, or they may radiate in a circle from a given point, as from the eye in most owls, 
where they form a disc. ; 
In the foregoing paragraph I only mention a few styles of crests, chiefly needed to be 
known in the study of our birds; but should add that there are many others, with endless 
modifications, among exotic birds ; to these, however, I cannot even allude by name. Peculiar- 
ities of nasal feathers, and others around the base of the bill, are noticed below. Forms of crests 
are illustrated by many of the figures given passim in the present work. 
2. OF THE MEMBERS: THEIR PARTS AND ORGANS. 
I. THE BILL. 
The Bill (Lat. rostrum) is hand and mouth in one: the instrument of prehension. As 
hand, it takes, holds, and carries food or other substances, and in many instances, feels ; as 
mouth, it tears, cuts, or crushes, according to the nature of the substances taken ; assuming 
the functions of both lips and teeth, neither of which do any recent birds possess. An organ 
thus essential to the prime functions of birds, one directly related to their various modes of life, 
is of much consequence in a taxonomic point of view; yet its structural modifications are so 
various and so variously interrelated, that it is more important in framing genera than families 
or orders; more constant characters must be employed for the higher groups. The general 
shape of the bill is referable to the cone ; ‘it is the anterior part of the general cone that we 
have seen to reach from its point to the base of the skull. This shape confers the greatest 
strength combined with the greatest delicacy ; the end is fine to apprehend the smallest objects, 
while the base is stout to manipulate the largest. But in no bird is the cone expressed with 
entire precision ; and, in most, the departure from this figure is great. The bill always con- 
sists of two, the upper and the lower 
Mandibles (fig. 26), which lie, as their names indicate, above and below, and are sepa- 
rated by a horizontal fissure, — the mouth. Each mandible always consists of certain project- 
ing skull-bones, sheathed with more or less horny integument in lieu 
of true skin. The frame-work of the Upper Mandible is (chiefly) 
a bone called the intermaaxillary, or better, in this case, the premaz- 
tllary. In general, this is a three-pronged or tripodal bone running 
to a point in front, with the uppermost prong, or foot, implanted 
upon the forehead, and the other two, lower and horizontal, running 
into the sides of the front of the skull. The scaffold of the Under 
Mandible is a compound bone called inferior maxillary ; it is U- or 
Fig. 26.— Parts of a Bill. 
a, side of upper mandible; }, 
culmen; c, nasal fossa; d, 
nostril; e (see below);./, gape, 
or whole commissural line; g, 
rictus; 4, commissural point 
or angle of the mouth; i, ra- 
mus of under jaw ; j, tomia of 
under mandible (the refer- 
ence lines e should have been 
drawn to indicate the corre- 
sponding tomia of upper man- 
dible): k, angle of gonys; 4, 
gonys; m, side of under man- 
dible; », tips of mandibles. 
V-shaped, with the point or convexity in front, and the prongs run- 
ning to either side of the base of the skull behind, to be there mov- 
ably hinged. These two bones, with certain accessory bones of the 
upper mandible, as the palate bones, etc., together with the horny 
investment, constitute the Jaws. Both jaws, in birds, are movable ; 
the under, by the joint just mentioned; the upper, either by a 
joint at, or by the elasticity of the bones of, the forehead; it is 
moved by a singular muscular and bony apparatus in the palate, 
further notice of which is given beyond, under head of Anatomy 
(Osteology). The motion of the upper mandible is freest and most 
extensive in the parrot tribe, where both fronto-maxillary and 
palato-maxillary sutures exist. When closed, the jaws meet and fit along their apposed edges 
or surfaces, in the same manner and for the same purposes as the lips and teeth of man or 
other vertebrate animals. All bills, thus similarly constituted, have been divided into 
