THE CHIMPANZEE AND ORANG UTAN. 857 
descending angle of the parietal, and separates the frontal from the temporal bone, as 
in Man. This is one of the few osteological differences in which the Orang has a closer 
approximation to the human structure than the Chimpanzee’. In a younger specimen 
of the adult cranium of the Orang I observed that the additamentum suture lambdoidalis 
was still visible on either side, but the remainder of the sutures, with the exception of 
those first mentioned, were obliterated. 
The occipital foramen approaches, in its figure, position, and aspect, nearer to that of 
the lower Mummalia. Its plane forms, with a line drawn parallel to that of the basilar 
process, an angle varying in three adult crania from 15° to 20°. The occipital condyles 
are more closely approximated anteriorly than in the Chimpanzee. The anterior con- 
dyloid foramina are double on each side ; they have the same relative position with 
the stylo-mastoid foramina as in the Chimpanzee ; the carotid foramina are situated 
more posteriorly, and are relatively smaller; the petrous portion of the temporal is 
smaller, while the glenoid cavity forms a much larger proportion of the base of the skull. 
This articular cavity, if such it may be called, presents a remarkable contrast with the 
numerous points of resemblance to the Carnivora observable in other parts of the cra- 
nium : it is a quadrate and almost flattened surface, slightly concave in the transverse, 
and slightly convex in the antero-posterior directions, affording an interesting corre- 
spondence with the structure of the molar teeth, and being, together with these, indi- 
cative of the vegetable diet of the animal. 
The styloid and styliform processes are wanting, as in the Chimpanzee. The mastoid 
process is represented by a protuberant ridge behind the auditory foramen ; and its 
cellular structure is visible from the thinness of the external table of the skull at this 
part. The ant-auditory process, which protects the articulation of the lower jaw, is 
more developed than in the Chimpanzee ; the margins of the auditory foramina are 
smoother. 
On the bony palate the relative positions of the foramina incisiva correspond with 
the increased development of the laniary teeth in the Orang, as compared with the Chim- 
panzee, and consequently deviate in a proportional degree from their position in the hu- 
man subject. They are situated upwards of an inch behind the incisor teeth, and two or 
three foramina remain on either side but more anterior, and indicate the original sepa- 
ration of the incisive bones. Small vascular foramina and grooves indicate, in the same 
manner, on the anterior part of the skull, the situation of the suture, or harmonia, 
which originally joined the incisive to the maxillary bones. The late period at which these 
sutures are obliterated forms an important differential character between the Orang 
' This affinity is of less value from the fact of some of the inferior races of Man occasionally presenting the 
same arrangement of these sutures as the Chimpanzee. 1 have observed the Junction of the temporal with the 
frontal bone in the cranium of a native of Australia, and in more than one negro. I have also observed the 
same disposition in one out of eight crania of the Simia Satyrus: this exception occurs in the skull of the 
adult, of which the entire skeleton is preserved in the Museum of the Royal College of Surgeons. 
VOL. I. 3B 
