COMPARATIVE ANATOMY. 



The accipitres, or rapacious birds, have 

 it very hard, hooked at the end, and 

 furnished with a process on either side ; 

 calculated, therefore, in all respects, 

 for seizing and lacerating- their prey. 

 Those of the parrot kind have it also 

 hard, for bruising the firmer vegeta- 

 ble fruits ; and the wood-pecker, nut- 

 hatch, &c. for penetrating the bark of 

 trees. 



Those birds, which take a softer kind 

 of food, and which require a sense of 

 feeling in the part, for distinguishing their 

 food in mud, water, See. have it approach- 

 ing to the softness of skin. Such are, the 

 duck, snipe, woodcock, &c. 



In several classes, particularly the ac- 

 cipitres and gallinse, the base of the bill is 

 covered with a soft skin, called the cire, 

 of unknown use. 



The cervical vertebrae of birds are 

 very numerous,and have a very free motion 

 on each other. This great mobility of 

 the neck enables the animal to touch 

 every point of its body with the bill ; 

 and 'thus supplies the want of the pre- 

 hensile faculty of the anterior extremity. 

 The sternum is prolonged below into a 

 vertical process (crista)'for the attach- 

 ment of the strong pectoral muscles, 

 which are the chief agents in the act 

 of flying. In the male wild swan (anas 

 cygnas) and in some species of the genus 

 ardea, as the crane, this part forms a pe- 

 culiar cavity for the reception of a consi- 

 derable portion of the trachea. The 

 crista is entirely wanting in the ostrich 

 and cassowary ; where the sternum pre- 

 sents, on its anterior or under surface, an 

 uniform convexity, and this peculiarity 

 of structure is accounted for by observ- 

 ing that these birds have not the power 

 of flying. 



The wings are connected to the trunk 

 by means of three remarkable bones. 

 The clavicles, which are always strong, 

 constitute straight cylindrical bones, ar- 

 ticulated to the sides of the front of the 

 sternum, and extending straight forwards. 

 Their anterior extremities are connected 

 to the sternum, by means of a bone pe- 

 culiar to birds, viz. the fork-like bone, or, 

 as it is more commonly termed, the mer- 

 rythought. (Furcula, in French, la lu- 

 nette or fourchette.) The scapula, which 

 is flattened in form, but elongated, ex- 

 tends backwards from the front of the 

 clavicle, parallel to the spine. The point 

 of the fork-like bone is joined to the most 

 prominent part of the keel of the ster- 

 num ; and the extremities of its two 

 branches are tied to the humeral ends of 



the clavicles, and the front of the scapu- 

 lae, just where these bones join each 

 other, and are articulated with the hu- 

 merus. Hence it serves to keep the 

 wings apart in the rapid motions of fly- 

 ing. 



As a general observation, it may be 

 stated, that the fork is strong and elastic, 

 and its branches wide, arched, and car- 

 ried forwards upon the body, in propor- 

 . tion as the bird possesses strength and 

 rapidity of flight; and accordingly the 

 strulhious birds (ostrich and cassowary,) 

 which are incapable of this mode of pro- 

 gression, have the fork very imperfectly 

 formed. The two branches are very 

 short, and never united in the African 

 ostrich, but are anchylosed with the 

 scapu la and clavicle. The cassowary 

 has merely two little processes from 

 the side of the clavicle, which are the 

 rudiments of the branches of the fork. 

 In the New Holland ostrich there are 

 two very small thin bones, which are at- 

 tached to ihe anterior edge of the dor- 

 sal end of the clavicles by ligaments ; 

 they are directed upwards towards the 

 neck, where they are fastened to each 

 other by means of a ligament, and have 

 no connection whatever with the ster- 

 num. 



The bones of the wing may be com- 

 pared, on the whole, to those of the up- 

 per extremity in man ; and consist of an 

 os humeri ; two bones of the fore-arm ; 

 two of the carpus; two, which are gene- 

 rally consolidated together, of the meta- 

 carpus ; one bone of the thumb, and two 

 fingers. 



The stork, and some others of the gral- 

 lae s which sleep standing on one foot, 

 possess a curious mechanism for preserv- 

 ing the leg in a state of extension, with- 

 out any, or at least with little, muscular 

 effort. There arises from the fore -part 

 of the head of the metatarsal bone a 

 round eminence, which passes up be- 

 tween the projections of the pulley, on 

 the anterior part of the end of the tibia. 

 This eminence affords a sufficient degree 

 of resistance to the flexion of the leg, 

 to counteract the effect of the oscilla- 

 tions of the body, and would prove an 

 insurmountable obstruction to the mo- 

 tion of the joint, if there were not a 

 socket, within the upper part of the 

 pulley of the tibia, to receive it when the 

 leg is in the bent position. The lower 

 edge of the socket is prominent and sharp, 

 and presents a sort of barrier to the ad- 

 mission of the eminence, that requires a 

 voluntary muscular exertion of the bird 

 to overcome, which being accomplished, 



