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 stUl; adcular (needle-shaped), when slenderest possible, as in some humming- 

 birds. A bill is arched, vaulted, turgid, 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 effected in the whale, 

 by the " bone " in its mouth. Finally, the far end of the biU, 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 uiider separate head of 



Tie Covering of the BUI (a.) In the great majority of birds, including nearly all 



perehers, 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 bOls as hard-covered as any, while some perehers have it partly quite 

 soft, so that no unexceptional rule can be laid down ; and, moreover, the gradations from one 

 extreme to the other are insensible. Probably the softest bUl 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 wonns out of sight in the mud. In all the duck 

 order the bill is hkewise soft ; but there it is always terminated by a hard, homy, umguis or 

 ''nail," more or less distinct ; and such a homy claw also occurs in other water birds with softish 

 biUs, as the pelican. An interesting modification occurs in all, 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 fi-om the rest 

 of the bUl, that it might be questioned whether it does not more properly belong to the head than 

 to the bUl, were 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 Stereorarius'). 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 f it may have a nail 

 at the end. (6.) The covering is either entire or pieced. In most birds it is entire ; that is, the 



