H. D. Smith 
259 
whole extent. The remaining specimen — a foetal cheiromys — showed the various 
components of the occipital entirely separate. 
Specimens Examined 
SlMIIDAE 
12 chimpanzees / g 
adult 
young 
5 gorillas 
{! 
3 adult 
young 
11 orang-outans 
5 adult 
6 young 
0 .it. f 2 adult 
6 gibbons-^ . 
° ^4 young 
Cercopithecidae 
57 various 
Cebidae 
29 adult 
28 young 
ln • f 10 adult 
19 various -J n 
{ 9 young 
Hapalidae 
5 various 
4 adult 
younj. 
Extending from 
Synchondrosis , Masto-occipital I n1 „ ,. 
Obliterated suture to Shorter Portlons 
Foramen Magnum 
17 
1 (acrocephalic) 
Certain specimens among both the Egyptian crania, and the other primates, 
show the synchondrosis associated with an ossicle at the masto-occipital end 
(see our Plate IV. B), and the writer finds that the persistent portions of the 
synchondrosis are invariably at this end. In no case has the condition been 
found like that cited as typical by A. Rambaud and Ch. Renault (Origine et 
Developpement des Os, p. 105 and Fig. 8, Plate VII.), where the ends of the 
fissure reaching the margin of the foramen magnum remain open after the other 
portions have been obliterated. 
It will be seen in Plate I. A that the line of the synchondrosis condylo-squamosa 
terminates internally in a small angular projection which forms the lateral boundary 
of a distinct median bay in the hinder margin of the foramen magnum. This bay, 
which has a breadth of 9 mm. and a depth of 4 mm., may be termed the opisthial 
notch, as corresponding to the region of the opisthion. Of the 85 crania which 
show some degree of the persistence of the synchondrosis condylo-squamosa, this 
notch is more or less marked in 43, whereas of 100 skulls taken at random from 
the series, which have the synchondrosis completely obliterated, an appreciable 
notch is present only in 9. A faint indication of the opisthial notch is however 
frequently to be recognised in the adult skull. 
33-2 
