QUADRUMANA. 



203 



wanted, and the rest of the sternum composed 

 of as many segments or sternebrce (BLAIN- 

 VILLE), as there are true ribs. 



The form of the ribs has much analogy in 

 the anthropo-morphous Apes with the ribs of 

 man. Their number corresponds with that of 

 the dorsal vertebrae; consequently it is 13 in 

 the Chimpanzee and in the Siamang, 14 in 

 some Gibbons, 12 in the Orang-oetan and in 

 the greater number of the other species of 

 monkeys. They form a very ample and con- 

 vex thorax in the Chimpanzee, the Orang-cetan, 

 and the Gibbons, which becomes gradually 

 more narrow and compressed in the Semno- 

 pitheci, the Inid, and Cynocepkali. In the 

 size and length of the anterior extremities, 

 the Orang-cetan and the Siamang are remote 

 from man, to whom the Chimpanzee ap- 

 proaches a little more. In the Orang-cetan 

 and in the Siamang they are so long that they 

 touch the ground, and in the quadruped 

 position of the trunk the Orang-cetan is forced 

 to curve the hands outwards, and to support 

 itself upon their dorsal surfaces. In the 

 Chimpanzee, sustaining himself in a semi-erect 

 position, they touch the superior third part 

 of the fibula. In the erect position of man 

 they descend not lower than the third inferior 

 part of the thigh. Consequently the Chim- 

 panzee, the Orang-cetan, and the Gibbons, 

 exhibit, as permanent conditions, proportions 

 of the posterior extremities, which in the 

 human subject are transitory, and proper to 

 the early periods of foetal life. It is, however, 

 according to the observations of Owen, a 

 remarkable fact, that in the young Chimpan- 

 zee the lower extremities, instead of being 

 shorter, in relation to the trunk, are longer, 

 their adult proportions arising from the in- 

 creased development of the trunk and ante- 

 rior extremities, which are thus made fit for 

 the vigorous acts of climbing. 



In the Chimpanzee the clavicle exhibits the 

 same sigmoid curve as in man, but the sca- 

 pula deviates from the human form by being 

 narrower, in proportion to its length, by the 

 spine running more in the direction of the 

 axis of the trunk, and by being situated more 

 towards the middle of the scapula, and more 

 perpendicular to its plane. The acromion 

 process is longer and narrower than in man. 

 In the Orang-oetan the scapula is broader and 

 more analogous to the scapula of man, but 

 its spine is inclined towards the superior 

 costa; its acromion is narrower and clavi- 

 form, and its coracoid process has a greater 

 inclination downwards. This inclination is 

 an indication of inferiority manifested in all 

 the lower species of monkeys, but it is wanted 

 in the Chimpanzee and in the Gibbons, in 

 which the coracoid process has the same 

 direction as in man. That it is an indication 

 of being placed on a lower scale is proved 

 by the fact, that in all the Mammalia with cla- 

 vicles the same disposition is observed. The 

 humerus is long in the Chimpanzee, and in all 

 the other long-armed Apes, in which also the 

 fore-arm is longer than the humerus, and 

 composed of two bones, radius and ulna, 



curved in two opposite directions, so that the 

 space existing between them becomes very 

 large. In the Mandrill, and all the other 

 monkeys of the Old World, the disproportion 

 between the anterior and posterior extremi- 

 ties exists no more ; or if there is a dispro- 

 portion, it is produced by the greater length of 

 the posterior extremities. The humerus and 

 forearm are in them almost of the same 

 length. The hand of the Chimpanzee is com- 

 posed of the same number of bones as the 

 hand of man ; but the trapezium and trape- 

 zoides are proportionally smaller, while the 

 os pisiforme is of larger dimensions, being 

 nearly equal to the os magnum. The small 

 size of the trapezium evidently relates to the 

 shortness of the thumb, which it supports. 

 The little finger is also shorter, as compared 

 with the other fingers, than in the human 

 subject. The metacarpal bones are chiefly 

 remarkable for their length; the phalanges, 

 both for their length and their interior curva- 

 ture. The hand is thus admirably formed 

 for clasping the thick boughs of forest trees. 

 On the sides of the anterior surfaces of the 

 first and second phalanges, there are ridges 

 for the insertion of the ligaments for the 

 tendons. 



The general opinion is, that the carpus of 

 the Orang-oetan offers the same number of 

 bones as in man and in the Chimpanzee ; but 

 I have proved in my Rech. d 'Anatomic comparee 

 sur le Chimpanse, that there is in the Orang- 

 cetan an additional bone, situated between the 

 two series of carpal bones (fg. 124.), which I 

 found also in the Gibbons, and which seems 

 to exist in all the lower monkeys. DE BLAIN- 

 VILLE has described it by the name of os 

 intermediaire. Its existence in the Orang- 

 a'taii, and its absence in the Chimpanzee, are 

 facts of some importance, as they prove that 

 also in this point of organisation the Chim- 

 panzee is superior to the Orang-cetan. 



Another character of the hand of the Orang- 

 oetan, and of all the other Monkeys of the Old 

 World, is the length and the narrowness of the 

 metacarpus, and the length of the digital pha- 

 langes, with the comparative shortness and 

 backward position of the thumb. The sole ex- 

 ception I know is in the Siamang, whose hand 

 represents almost the hand of man, on a more 

 elongated scale. The trapezium is not situated 

 on the same level as the other bones of the 

 carpus ; consequently the thumb, the bones 

 of which are comparatively longer and thicker 

 than in the Chimpanzee or Orang-cetan, can 

 be opposed to the other fingers. The middle 

 finger is the longest, and the metacarpal bones 

 decrease from the index to the little finsrer in 

 the same manner as in man. In the Mandrill, 

 on the contrary, the four metacarpal bones of 

 the fingers are of the same length, and the 

 middle finger is not longer than the other. 

 Thereby the forehand loses all its analogy 

 with the hand of man, and approaches to the 

 form of the paws in the Camivora. In the 

 Semnopitheci the thumbs offer a dispropor- 

 tionate shortness, which scarcely surpass the 

 rudimentary form, and prepare us in some 



