BILL, in natural history, the hard, horny mouth of birds (q.v.). It consists of two main/fake, an upper and a lower, into which the upper and lower jaws are respectively produced, all appearance of lips beinglost. It is not famished with proper teeth, although rudiments of them have been observed in some of the parrot tribe iu the fetal state, anti the marginal lamiute with which the bills of many water-fowl are furnished. partake of the same character, being secreted by distinct pulps. The resemblance of these mar ginal laminae to teeth is particularly marked iu the goosander (q.v.). The bills of birds differ much, according to their different habits, and particularly according to the kind of fond on which they are destined to live, and the manner in which they are to seek it. In birds of the It is strong; the upper mandible arched or hooked, and very sharp; the edges sharp, often notched, and the whole B., or beak, adapted for seizingqnimals, and tearing and cutting to pieces their flesh. A powerful, short, hooked beak, sliafp-edged and notched, indicates the greatest courage and adaptation to prey on living animals. The beak of the vulture is longer and weaker thou that of the eagle or falcon. In birds which feed on insects and vegetable substanees, the hooked form of the B. is not found, or it is in a very inferior degree; those birds which catch insects on the wing, such as the goat-suckers. are remarkable for the deep division of the B., and their consequently wide gape, and an analogous provision to facilitate the taking of prey is to be in herons, kingfishers, and other tishing-birtls; but the object is attained in their case by the elongation of the B., whereas birds which catch insects on tl.e wing have the B. very short. Birds which feed chiefly on seeds have the B. short and strong. for bruising
them; whilst the II. of insectivorous birds is comparatively slender. 3Iany aquatic birds have broad and comparatively soft and sensitive bills, with lamina on the inner mar gin for straining the mud front which much of their food is to be extracted; other birds, as snipes, avocets, etc., seeking their food also in mud, have slender bills of remarkable sensibility. The modifications of form are very numerous, and the peculiarities of the bills of toucans, hornbills, spoonbills, crossbills, parrots. humming-birds, etc., are very interesting. and intimately connected with the habits of 11.1- different creatures. (See these articles.) At the base of the upper mandible, a portion of the B. is covered x% ith a membrane, called the are (Lat. cent, wax, from the waxy appearance which it pre sents in some falcons, etc.). which in many birds is naked, in others is feathered, and in many is covered with hairs or bristles. The nostrils are situated in the upper man dible, usually in the core, but in some birds they are comparatively far forward, and in' some, ns nith's they are very small and placed so near the edge of the mandible, as not to be easily aetected. Th y are more or less open. or covered with membrane, or protected by hairs or feathers. resides their principal use for seizing and dividing or triturating food, the bills of birds are employed in tt variety of functions, as dressing, or preening, the feathers, constructiug nests, etc. They are also the principal instruments used by birds in their combats.
'flie months of some fishes and reptiles assume a character somewhat analogous to that of the B. of birds. .