100 GENERAL ORNITHOLOGY. 



a velvety pDe, 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 MJEMBEMS: THMIB PARTS AND ORGANS. 



I. THE BILL. 



The Bill (Lat. rost/rvm) is hand and mouth in one : the instrument oi 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 ftmctions 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 skuU-bones, sheathed with more or less horny integument in lieu 

 of true skin. The frame-work of the Upper Mandible is (chiefiy) 

 a bone called the intermaxillary, or better, in this case, the premax- 

 illary. 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 skuU. The scaffold of the Under 

 / / ""■•.' \ Mandible is a compound bone called inferior maxillary ; it is U- or 



ifiG. 26. — Parts of a BUI. V-shaped, vnth the point or convexity in front, and the prongs run- 

 a, side of upper mandible ; b, ning to either side of the base of the skull behind, to be there mov- 



no'sWi'^Mtow^rgapt; ^l^ly ^^""S^^; These two bones, with certain accessory bones of the 

 or whole commissural line; jr, upper mandible, as the ^aZafe bones, etc., together with the horny 

 «lng\e'ifTe mouth! fl^ ^vestment, constitute the Jaws. Both jaws,.in birds, are movable; 

 musof under jaw; j'.tomia of the under, by the joint' just mentioned; the upper, either by a 

 eTc"sTshouid'h:ve™S; J""* ^'' °' ^^ '^' ^^^^^city of the bones of, the forehead; it is 

 drawn to indicate the corre- moved by a singular muscular and bony apparatus in the palate, 



spondiDgtomia of upper man- farther notice of which is given beyond, under head of Anatomy 

 dible); ft, angle of gonys; «, .-^ _ > __,, . e t 



gonys; m, side of under man- (Osteology). The motion of the upper mandible is freest and most 

 dible; », tips of mandibles. extensive in the parrot tribe, where both fronto-maxiUary and 

 palato-maxUlary 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 





^/! 



