THE CHIMPANZEE AND ORANG UTAN. 363 
the spinal canak, which is peculiar to five, leaving three not so perforated for the coccyz. 
Camper, who appears to have reckoned those vertebre only as sacral which transfer the 
weight of the trunk upon the pelvic arch, allows only three sacral vertebre to the Orang, 
and counts the rest as coccygeal, omitting, however, the last, and thus making only 
seven false vertebra, which is one short of the true number in the Orang. 
The coccygeal vertebre are anchylosed together, but not with the sacrum, in the adult. 
The ilia are rather more expanded than in the Chimpanzee, but are flatter. The ischia 
are less extended outwardly, so that the lower part of the pelvis is narrower, correspond- 
ing with the small size of the lower extremities. Both the ischia and ossa pubis re- 
semble 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 
spine of the os pubis is well marked, but at a greater distance from the symphysis than 
in the human subject. The form of the superior aperture of the pelvis is an almost 
perfect oval, the antero-posterior diameter of which is to the transverse as 3 to 2. The 
axis of the brim forms with that of the outlet of the pelvis a much more open angle 
than in the human subject, whence it may be inferred that parturition is much easier 
in the Orang. 
The chest has the same amplitude of development in the Orang as in the Chimpanzee; 
it equals in size that of the human subject, and the transverse diameter is greater 
than the antero-posterior. The ribs are narrower and less flattened in their form. The 
cartilages of the first and second pairs are proportionally longer. The twelfth or last 
rib 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 
manubrium, or first bone, of a double series of small bones, seven or eight in number : 
this structure is always obvious in the Simia Satyrus, or young animal ; and in the 
skeleton of the Pongo preserved in the Museum of the College of Surgeons, the four 
upper bones are still separate, and traces of the harmonie which joined the four lower 
bones are very evident. While in Paris, I carefully examined the sternum of the great 
Pongo in the Museum of Comparative Anatomy at the Garden of Plants: the oblique 
transverse harmonieé resulting from the alternating position of the original double series 
still remained, but the mesial harmonia were almost obliterated, so that the sternum 
would appear, to one who had not studied its composition in the young Orang, as if 
composed of a single series of broad oblique ossifications. In the young Chimpanzee the 
sternum is composed of a single series of bones, as in most other Mammalia; and the 
same structure is shown in the adult. In the human subject, although at the early 
period of ossification a single series of ossific centres appear, yet at a later stage the 
lower part of the sternum is frequently seen to be composed of a double series of bones. 
The clavicles deviate from those of the Chimpanzee and of the human subject in being 
less curved: in the skeleton of the Pongo at the College of Surgeons they are almost 
straight. The scapula differs from that of the Chimpanzee in its greater breadth, and 
