THE i:u.\i:s i\ mints. 117 



i, ami arc usi.ally absent in the first and last ribs. They concur in on 

 etlica>-ioii~ manner to increase the solidity of the thorax. 



Tin' c..stal cartilages in n ammalia are in birds oft< n transformed into veritable 

 infciior ribs, joim -d to tin- siiperii r iil>s 1 y a diarthrodial articulation (Fig. 73, i). Th n 



- an- long ami strong, ami nil t rminale at llu-ir lower cxtn mity l>y a double 

 which articulates with the lateral border of the sternum; they are nearly always 



in the two tirst ril>s. It is n..t rare to seethe last united to the one before it, 

 1 of pas-ing direetly t. the ttcrnum; in which case it comports itself like the 



he mammalia. 



\ n KIDIS MKMIIKKS. tflioidrter-bone. The shoulder comprises: a tcapula ; a par- 

 ticular l>ne named the coracoid by Cuvier; and a i-lnvicle, which forms, in coalescing 

 with that of the ophite side, a single bone culled the fork (furculum), or o furculare. 

 Tlie f.-:i;->ilu is narrow, elongated, and falciform, and shows no trace of a spine. Its 

 anterior extremity only forms a portion of the glenoid cavity, and is united by means of 

 a ribro-cartilage with the/orfc of the coracoid bone. The latter is so named because it 



- nts the coracoid process of mammals, and is a long piismatic bone, directed 

 obliquely from al><-ve downwards, and before to behind. Its superior extremity is often 

 fused \\itli the scapula, and united at an acute angle with that boue to form a portion of 

 the artieular cavity which receives the head of the humerus. Its inferior extremity is 

 tlattemd t'n'iu before to behind, and responds by a diarthrodial articulation to the 

 anterior border of the sternum. The coracoid is long in birds which fly slowly ; it is, on 

 the contrary, short, thick, and therefore very tolid in quick flyers. The fork is a single 

 bone, shaped like a V or U, situated at the base of the two wings, in front of the trunk, 

 und in an oblique direction downwards and backwards. The two branches which form 

 it rcpre-ent the clavicles; they meet and are united at their inferior extremities, where 

 they de.-eril>e a curvilinear angle more or less open, attached to the brisket by means of 



iibranous ligament. Their superior extremity rests within, and opposite to the 

 glenoid cavity, against the scapula and coracoid, forming with these bones a remarkable 

 foramen, through which passes the tendon of the elevator muscle of the wing (Fig. 73, 

 A. 4. n. U). The fork plays the part of an elastic spring, whose office it is to prevent the 



- coming towards each other during contraction of the depressor muscles. The 

 mation of this bone is, therefore, like the sternum, related to the extent and power of 



flight ; and for this reason it is that, in swift flyers, the two branches of the furculum are 

 thick, solid, widely .-. jtarated, and curved like a U; while in those which fly heavily and 

 with difficulty, tli- > branches are thin and weak, and joined at nn acute angle. The 

 latter formation greatly diminishes its strength, and lessens, in a singular manner, 

 the reactionary jxnvcr of the bony arch it represents. 



I'x-if of the 'inn. The hnnti'rus oftVrs an articular oval-shaped head, and an air- 

 o|-ninu pwaed beneath this eminence. It is long in Palmipedes, ordinarily so in the 

 iliilliii' . uml very short in 1'iijnin*. 



Bone* of ti,< fi'i-'-iirm. The radius is much less voluminous than the ulna. The 



latter has nn extremely short olecranon ; and the two bones are separated from one 



another in their middle part t> meet again at their extremities, where they are united 



by ligiuucnloiis ImmLt in such a way as to rentier tin- movi mints of pronation and 



.-upiiiation impossible. This mode of fastening, which m v. rtlw ' .-- >!o ( > n.-t pievent the two 



from gliding slightly on . ach other in the direction of their length, has been wisely 



adopted by nature in order that the wing might strike the air. like an oar, by its inferior 



the resistance of the aerial medium v.oiild m:ike these two bones pivot, 



i-e the wing to present itself to the air in a wrong direction. 



yyn<'X i if the. cta-jiu*. These are only two, ami are distinguish! d by the names of 



- ami iiliin, in ci,n.-i '|uciice of their corrvsi>onding more p-cirticulurly to these bones 

 r animal-. 



Jion'x of tin iifl'i'-ttri-n.". Th'-e also number only two, and are separated at their 

 middle ]*>rtiiin, to l- eon.-j'lid tt d at their extremities. 

 ' 



"t of the iliif'tnl rji'>n. The wing of a bird is composed of three digits. One 

 tn, wiii.-h re>, iul.1. .-the thumb ami forms the basis of the false wing, is composed 

 of a single st\loid-.>haped phalanx, articulated at the base of a small particular process 

 to the superior extremity of the largest metacari>al bone. The largest digit 

 AO phalanges which succeed the last bone. The third digit is represent' 

 a small rudimentary ph.ilanx. whi h corresponds to the inferior extremity of the small 

 metacarpal bone, and lie- \., -.\>\,- the lirat ]>halanxof the large di-it in the. ': ------ 1 m .nner. 



It i- w. 11 to remark that the band and the fore-arm are longer iu proportion to the 

 quality of tlight; those two regions of the wing, for example, are very short iu <.'<!///// 



u MEHBEBS. Coxa or 09 iliac. This is a voluminous ami very solid piece. 



