122 AVES. 



body, consequently, is inclined before their legs, the thighs directed 

 forwards, and the toes elongated, to form a sufficient base for it. The 

 pelvis is very much extended in length, in order to furnish points of 

 attachment to those muscles which support the trunk upon the thighs. 

 There is even a suite of muscles reaching from the pelvis to the toes, 

 passing over the knee and heel, so that the simple weight of the 

 bird flexes the toes; it is thus that they are enabled to sleep in secu- 

 rity, while perched on one foot. 



The neck and the beak are elongated to reach the ground, but 

 the former has the requisite flexibility for bending backwards when 

 at rest, — consequently, it has many vertebrae. The trunk, on the 

 contrary, which serves as a point d'appui to the wings, has but little 

 mobihty; the sternum, particularly, to which are attached the 

 muscles which lower the wings in flight, is of great extent, and has 

 its surface still more enlarged by a salient process in its middle. It 

 is originally composed of five pieces. The greater or less degree of 

 the ossification of the notches, and the extent of the interval they 

 leave between them and the principal bone, denote a relative strength 

 of wing and power of flight. The Diurnal Birds of Prey, the Swal- 

 lows and the Humming-birds, lose, as they grow old, all traces of 

 these unossified spaces. 



The fourchette produced by the junction of the two clavicles, 

 and the two powerful stretches formed by the coracoid apophyses, 

 keep the shoulders apart, notwithstanding the eflfbrts requisite for 

 flight, that act in an opposite direction; the greater the power of 

 flight, the more open and strong is the fourchette. The wing, sup- 

 ported by the humerus, fore-arm and hand, the latter of which is 

 elongated and has one finger and vestiges of two others, is furnished 

 throughout its length with a range of elastic quills, which greatly 

 extends the surface that resists the air. Those which belong to the 

 hand are iermeA primaries ^ and there are always ten; those attached 

 to the fore-arm are called secondaries, but their number varies; 

 weaker feathers appended to the humerus are called scapulars; the 

 bone, which is analogous to the thumb, is also furnished with what 

 are termed spurious quills. Along the base of the quills is a range 

 of feathers named coverts. 



The bony tail is very short, but has a range of large quills, which, 

 when spread out, assist in supporting the bird; they are generally 

 twelve in number, sometimes fourteen, and in the Gallinaceae 

 eighteen. 



