EXTERNAL PARTS OF BIRDS. — THE BILL. 



107 



iumid, inflated, etc., when its outliues, both crosswise and lengthwise, are notably more or less 

 convex; and contracted, when some, or the principal, outliues are concave (said chiefly of de- 

 pres'^ions about base of upper mandible, or of concavity along sides of both mandibles). A bill 

 is hamulate (Lat. hamus, a hook), or ungukulate (Lat. unguis, a claw),.whcu strongly epigna- 

 thous as in rapacious birds, whose 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, or denticulate, as in Motmots, Trogons, some Humuungbirds, 

 etc •" it is adtrate (knife-like), when extremely compressed and sharp-edged, as in an Auk or 

 Skimmer- if much curved as weU as cultrate, it is falcate (Lat. falx, a reaping-hook ; scythe- 

 shaped); and each mandible may be oppositely falcate, as in a Crossbill, constituting metag- 

 nathism A gibbous bill is one which has a pronounced hump or knob, as that of some Swans 

 and Scoters; and some bills are appendaged with various leathery or skinny lobes or flaps. A 

 biU much flattened and widened at eud (rare) is spatulate (Lat. spatula, a spoon) ; examples: 

 Spoonbill. Shoveler Duck, and the extraordinary little Sandpiper whose technical name is 

 Eurynorhynchus pygmceiis. One is called lamellate, when it has a .series of plates or processes 

 just inside the edges of the mandibles, as in all Ducks, etc., furnishing a sifter or strainer of 

 ■^-ater- just what is effected in the whale by the '' bone " in its mouth. The commonest shape 

 of a bill is conical, as in any Finch, Bunting, or Warbler; probably the next commonest is 

 that called by some ornithologists grypaniform, such as is exhibited by any Thrush or War- 

 l.ler — the grypaniform being a mild case of epignathism, usually associated with weak tooth- 

 ing or nicking. 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 contmmty. 



Particular shapes of bills are almost endlessly varied, and cannot be given ; the student 

 who uses this book to the end will find many of them described, and " there are others." One 

 of the most curious cases is that of the New Zealand Huia, Heteralocha acutirostris, in which 

 shape of bill is a sexual character ; for in the <? the bill is comparatively short and straight, 

 but in the 9 it is about twice as long and curved almost in the arc of a circle. 



Covering of the Bill. — (a) In a great majority of birds, including nearly all perchers, 

 many walkers, and some waders and swimmers, the sheathing of botli mandibles is wholly 

 hard, horny, or corneous (Lat. cornu, a horn) ; it is integument modified much as in case of 

 nails or claws of beasts, by thickening and hardening of outer layers of malpighian cells. In 

 nearly all waders and most swimmers, the sheath becomes softer, and wholly or partly of a 

 dense, leathery texture. But many swimmers furnish bills as hard-covered as any, while some 

 perchers have the integument partly quite soft, so that no unexceptional rule can be laid down ; 

 moreover, gradations from one extreme to the other are insensible. Probably the softest bill 

 is found in Scolopacida:, where it is skinny throughout, and in typical Snipes and Woodcocks 

 vascular and nervous at 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 always ends in 

 a hard, \\o\uy tinguis or "nail," more or less distinct; and such a horny claw also occurs in 

 other water birds with softish bills, as Pelicans. An interesting modification occurs in the 

 Pigeon order (Columba') ; these birds have the bill hard or hardish at tip and through most of 

 continuity, but toward and at base of upper mandible the sheath changes to a soft, tumid, 

 skinny texture, overarching the nostrils ; and the case is much the same with most Plovers. 

 But the most important feature in this connection is afforded by Parrots and all Birds of Prey 

 — one so remarkable that it has received a distinct name : Cere (or ceroma). 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 proi>- 

 erly belong to head than to bill, were it not that the nostrils open in it. A cere is often densely 

 feathered, as in the Carolina paroquet, in the bill proper of which no nostrils are seen, these 



