( 531 ) 
Among the Catarrhine monkeys, the greatest angles, 80J and more, 
occur among the Anthropoids and the genus Cercopithecus. This 
genus thus, also as regards the slope of the Foramen magnum, takes 
fh e hi „ h place which we have already awarded to it in the previous 
paper on account of the position. And similarly the genus biamanga 
takes again the lowest place among this group ot Primates. In this 
otherwise so highly developed monkey the Foramen magnum is 
inclined more vertically than in any other family of monkeys of 
the Old World, although it is closely followed by the genus Sem- 
nopithecus. A study of the skull base will afford us the opportunity 
of pointing out more particularly what a quite dt«>nc pl^e the 
Siamanga takes in the group of Primates as regards the generel 
form of the cranium. In the first paper I have already mentioned 
that it is difficult to believe that original conditions have been here 
foregoing paper it was also pointed out that during the 
infantile and juvenile period the For. magn. shifts towards the 
occiput. It appears now that also the slope of the Fora “ en ^®“ 
during growth. For in the skull of a young ape the Foramen 
magnum lies more horizontally than in that of a 
The following may serve as a proof of this. Whereas in a full-grown 
Siamanga the angle varied between 55°mid68 , I foun 
skull (mixed dentition) an angle of W. and m an in&ntde Ml 
(complete lactal dentition) an angle of 81 ■ ^ a <.|horizontallv 
a complete set of milk teeth, the For. magn. lay almo ' 0“"* 
with a angle of 88°. In three infantile Orang-outang skulls I found 
SJTn-. 85-, 86-, 
had a angle of 87° and an infantile one even of 95 . 
of this las. skull, thus, the For. magn. looked forwards as m that 
of man. We shall soon see that as regards human ato the 
plane of the For. magn. turns during infantile an ® ?? 
Tn the same manner as with the Anthropoids, M .1 1 must Imre 
point out that this turning is much more pronounced ,n Anthropoids 
and Siamanga than in human beings. „ M 
Thus both in the position and the slope of the * 
young Anthropoid agrees more with the human condthms than the 
'trzx the ° f the F ° r - maen -’ man °“ upie L a t d t u™^ 
place among all Primates, as in him the opening! ■ «* 
towards the back but towards the front. “ * writers on 
been alluded to by Dsubbnton, and after im - a ^ 
this subject, is illustrated by the figures below. I call to mind that 
