ORDER ACCIPITRES. 101 



its immense pectoral muscles into action, in lowering the wings 

 in flight. The insertion of the coracoid apophyses prevents 

 the lowering of the shoulder-blade, by which the wing acts with 

 greater effect upon the resisting air. In birds of powerful flight 

 it is larger than the humerus, but in the gallinaceous birds these 

 parts are of about equal length, and in the ostrich the humerus 

 is longer than the radius or the cubitus. 



Birds have three pectoral muscles, one of which Aveighs 

 more than all the other muscles of the body put together. 

 The middle pectoral muscle acts as a lever to the wing, and 

 prevents the bird turning over in flight. 



The extremity of the wing, analogous to the hand, or fore- 

 feet of mammalia, has a range of carpal bones, a single meta- 

 carpal bone, and a bone called os stylo'ide, which represents 

 the thumb and toe, with two phalanges, and another os 

 stylo'ide smaller than the first. These bones have not, like 

 ours, the movements of pronation and supination, but only 

 those of extension and flexion. The muscles and tendons 

 which move them with such vigour, will allow of no other; for 

 the wing must be strong enough to resist the shock of the air, 

 without turning, which would overthrow the bird. 



Like quadrupeds, the birds possess the principal organs of 

 life, as the intestinal tube, which no animals can want, a heart, 

 with two ventricles and two auricles, a double and perfect cir- 

 culation, lungs, brain, parts of generation, &c., all adapted to 

 their peculiar nature of life. 



But they are destitute of many parts which the quadrupeds 

 possess. Thus, they have neither lips, teeth, oreillon, or fleshy 

 tail. In the interior of the body, they are without the dia- 

 phragm, epiglottis, and urinary bladder. They pass some 

 urine, however, into the cloaca of the excrements, through the 

 ureters. Many parts are modified differently from their ana- 

 logous ones in quadrupeds ; thus, the female birds have but 

 one ovary and oviductus, instead of the matrix of the vivipara. 

 The males have no scrotum, but the testes are situated in the 

 belly, near the reins and lungs. 



