114 
formed totally on the occipital surface, naturally there is not one 
single pli de passage pushed down in the depth. These remain in 
front of the ape fissure on the surface. 
In ateles and related monkeys therefore all the plis de passage 
are lying on the surface. 
But when the fissura simialis becomes but deep enough, then there 
will be such important contorsion of the brainsurface which is pushed 
down, that the conformity with plis de passage, superficially exa- 
mined, becomes very great. If one however observes the origin of 
these plis, and curves, then they appear to have been formed 
out of a former smooth brainsurface. These therefore are not real 
plis de passage. 
Again different is the relation in the anthropoids. 
That in the latter it entirely changes, one learns from the report 
of Bork ©) of two gorillabrains. 
On his figures 4(4) and 7(b) the sulcus interparietalis (/ + ¢) proves 
to end in the ape fissure. On fig. 4 the ape fissure continues over 
the edge of the brainmantle on the medial surface. On the right 
hemisphere (p. 205, fig. 18) the ape fissure does not come in con- 
nection with the w suleus (par. oee. med). This happens however 
on the left brainhalf (p. 220, -fig. 24). On fig. 7 again it is different: 
there the ape fissure on the left side only comes to the edge of the 
Grainmantle, on-the right it does not even reach the latter. 
As from the above mentioned the incissura parieto-occ. med. proves 
not onee to have penetrated into the depth, it follows without more 
that the interposed pli de passage (gyr. annectens interpositus mihi, 
or 1st lateral pli de passage of GratioLnr) has only disappeared for 
a small part in the ape fissure. 
This agrees on the whole with the researches of others on gorilla- 
brains, which had as result that the interposed pli de passage 
totally remains on the surface. 
Although this last does not quite agree with the researches of 
Bo.k, yet they agree that the ape fissure in anthropoids, as to the 
medial part, is not by far so well developed as in the semnopitheci. 
As to the lateral pli de passage (gyrus annectens lateralis) this 
remains in gorillas related in the same way as in semnopitheci and 
macaci. It is found therefore between the m and / sulcus and a 
smaller or larger part of it will be pushed down in the depth. 
An exception to this is given by the view which Bork shows us on 
fig. 8, p. 153. By the strong development of the back branch (a? of 
1) Bork, ae Beiträge zur Affenanatomie. — Das Gehirn von Gorilla. — Zeitschr. 
t. Morph. u. Anthr 1909. 
