Comparative Osteology of the Ora?ig Utan and Chimpajtzee, ^Q5 



ral curve dorsad from the atlas to the commencement of the sacrum, 

 where there is a slight curve in the contrary direction. As in Man, 

 the number of the dorsal or costal verlehrce is twelve, and this con- 

 stitutes one of the more important differences between the Orati'r 

 and the Chimpanzee. That of the lumbar vertehrce is four, as in the 

 Chimpanzee, in the skeleton of the Pongo preserved in the Museum 

 of Comparative Anatomy at the Garden of Plants, and in the trunk 

 of the skeleton of the adult Orang in the collection of the Society ; 

 in which latter, as the bones remain connected by their natural liga- 

 ments, there is no room for supposing a vertebra to have been acci- 

 dentally lost. The additional lumbar vertebra in the skeleton of the 

 Pongo in tlie College of Surgeons, on which some stress has been 

 laid, as indicative of its specific difference from the young Orang, 

 which has uniformly presented but four, indicates its abnormal cha- 

 racter by its form and situation. The human subject occasionally 

 presents a similar lusus in the addition of a sixth lumbar vertebra. 

 The spines of these vertebrce are much shorter than in the Chim- 

 panzee: as in the latter, the sacrum is longer, narrower and straighter 

 than that of Man. Five sacral vertebrce are perforated for the 

 passage of the spinal cord ; three are imperforated, and are conse- 

 quently coccygeal : the latter are anchylosed together, but not with 

 the sacrum, in the adult. 



The ilia are as much expanded as in the Chimpanzee, but flatter ; 

 and the ischia are less extended outwards, corresponding with the 

 smaller development of the lower extremities. Both the ischia and 

 ossa pubis resemble those of the Chimpanzee, in their more elongated 

 form ; and the whole pelvis equally deviates from the Bimanous type 

 in its position with regard to the trunk. The form of its superior aper- 

 ture is an almost perfect oval, the antero-posterior diameter of which 

 is to the transverse as three to two ; and the axis of the brim forms, 

 with that of the outlet, a much more open angle tlian in the human 

 subject. The chest is amply developed, equalling in size that of 

 the human subject, except in being somewhat narrower from side to 

 side. The ribs are narrower and less flattened, but their curvature 

 is nearly the same as in Man ; the twelfth is much longer, and has 

 a long cartilage at its free extremity. The sternum is short, but 

 broader than in the Chimpanzee: it is composed, below the manu- 

 brium, of a double series of small bones, seven or eight in number. 

 This composition, always seen in the young Orang, is sufficiently 

 obvious in the adult Pongo in the Museum of the College of Sur- 

 geons, but much less so in that of the Garden of Plants at Paris. 

 In the young Chimpanzee ihe sternum is composed of a single series 

 of bones; while in the human subject, although at an early period 

 of ossification, a single series only of ossific centres appears : at a 

 later stage the lower part of the sternum is frequently seen to be 

 composed of a double series. 



The clavicles are almost straight; and the scapula also differs from 

 that of the Chimpanzee in its greater breadth, and from that of Man 

 in the inclination of its spine towards the superior costa, in thcacn- 



Third Series. Vol. 6. No. 36. June 1835. 3 O 



