102 
GENEBAL OBNITHOLOGY. 
obtuse (said chiefly of the paragnathous sort) when it rapidly comes to an end that therefore 
is not fine ; or when the end is knobhy ; it is acute when it runs to a sharp point ; acuminate, 
when equally sharp and slenderer; attenuate, when still slenderer; subulate (awl-shaped), 
when slenderer still; acicular (needle-shaped), when slenderest possible, as in some humming- 
birds. A bill is arched, vaulted, tUiVgid, tumid, inflated, etc., when its outlines, both crosswise 
and lengthwise, are notably more or less convex ; and contracted, when some, or the principal, 
outlines are concave (said chiefly of depressions about the base of the upper mandible, or of 
concavity along the sides of both mandibles). A bill is hamulate (Lat. hamus, a hook), or 
unguiculate (Lat. unguis, a claw), when strongly epignathous, as in rapacious birds, where 
the upper mandible is like the talon of a carnivorous beast ; it is dentate, when toothed, as in 
a falcon ; if there are a number of similar teeth," it is serrate (Lat. serra, a saw), like a saw ; 
it is cultrate (knife-like), when extremely compressed and sharp-edged, as in the auk, skimmer ; 
if much curved as well as cultrate, it is falcate (Lat. falx, a reaping-hook ; scythe-shaped) ; 
and each mandible may be oppositely falcate, as in the cross-bill, constituting metagnathism. 
A bill much flattened and widened at the end (rare) is spatulate (Lat. spatula, a spoon) ; 
examples : spoonbill, shoveller duck. One is called lamellate, when it has a series of plates 
or processes just inside the edges of the mandibles ; as in all the duck order, and in a few 
petrels ; the design is to furnish a sifter or strainer of water, just what is efi"ected in the whale, 
by the bone " in its mouth. Finally, the far end of the bill, of whatever shape, is called the 
tip or apex (fig. 26, n) ; the near end, joined to the rest of the skull, the base ; the rest is the 
continuity. Some other features of the bill as a whole are best treated under separate head of 
The Covering of the Bill. — (a.) In the great majority of birds, including nearly all 
perchers, many walkers, and some waders and swimmers, the sheathing of the mandibles is 
wholly hard, horny, or corneous (Lat. cornu, a horn) ; it is integument modified much as in 
the case of the nails or claws of beasts. In nearly all waders and most swimmers, the sheath 
becomes, wholly or partly, softer, and is of a dense, leathery texture. But some swimmers, as 
among the auks, furnish bills as hard-covered as any, while some perchers have it partly quite 
soft, so that no unexceptional rule can be laid down ; and, moreover, the gradations from ones 
extreme to the other are insensible. Probably the softest biU is found among the snipes, where 
it is skinny throughout, and in typical snipes and woodcocks vascular and nervous at the tip, 
becoming a true organ of touch, used to feel for worms out of sight in the mud. In all the duck 
order the bill is likewise soft ; but there it is always terminated by a hard, homy, unguis or 
nail," more or less distinct ; and such a homy claw also occurs in other water birds with softish 
bills, as the pelican. An interesting modification occurs in aU, or nearly all, of the pigeon order ; 
these birds have the bill hard or hardish at tip and through most of continuity, but towards 
and at the base of the upper mandible the sheath changes to a soft, tumid, skinny texture, 
overarching the nostrils ; it is much the same with most plovers. But the most important 
feature in this connection is afforded by the parrots and all the birds of prey ; one so remarkable 
that it has received a distinct name : Cere. The cere (Lat. cera, wax ; because it looks 
waxy) is a dense membrane saddled on the upper mandible at base, so different from the rest 
of the bill, that it might be questioned whether it does not more properly belong to the head than 
to the bill, M^ere it not for the fact that the nostrils open in it. Moreover, the cere is often 
densely feathered, as in the Carolina paroquet, in the bill proper of which no nostrils are seen, 
these being hidden in the feathered cere, which, therefore, might easily be mistaken at first sight 
for the bird's forehead. A sort of false cere occurs in some water birds, as the jaegers, or skua- 
gulls (genus Stercorarius). The tumid nasal skin of pigeons is sometimes called a cere; but 
the term had better be restricted to the birds first above named. The under mandible probably 
never presents softening except as a part of general skinniness of the bill ; it may have a nail 
at the end. (b.) The covering is either entire or pieced. In most birds it is entire ; that is, the 
