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unaltered. As the ape fissure, to my knowledge, never continues 
until the fissura calcarina, this pli de passage always remains on 
the surface. 
As the above-mentioned brings about an important change in our 
conception concerning the plis de passage it is desirable, that the 
names keep count with it. 
1. In relation to the localisation I therefore propose to call the 
pli de passage, which lies between the s. oce. inf. (6) and the lateral 
part of m (s. par. oce. lat.) on fig. 3, indicated sub 2 and 3: the 
gyrus annectens lateralis. This thus agrees with the 2rd, 3rd and 4ti 
pli de passage of GRaTIOLET. . 
2. We shall call the communication between lobus parietalis and 
occipitalis on fig. 3, indicated sub 1: the gyrus annectens interpositus. 
Thus it is found between the lateral and medial one and agrees 
with those two which were put down as the 1“ lateral and upper- 
medial ones of GRATIOLET. | 
It will be superfluous to call special attention to the fact, that 
there where this bridging convolution already exists before the ape 
fissure is formed and commences as a whole, that there the hypo- 
thesis of ZUCKBRKANDL, which I already in short referred to and 
according to which it should be formed out of two portions, is wrong. 
3. We shall call the communication between cuneus and prae- 
cuneus (fig. 3 sub 4) the gyrus annectens medialis. This agrees there- 
fore with the lower inner pli de passage of GRATIOLET. 
The question as to the relation of the plis de passage in other 
monkeys now arises. 
In my former report I pointed out that the place where the ape 
fissure is being formed, can be totally different in different monkey- 
species. 
Thus it is known that in some of the platyrrhines, e. g. ateles, the 
sulcus interparietalis (/ + ¢) although ending in a T-piece, in the 
same way therefore as in the semnopitheci, ending in the mm —+ mm’ 
suleus (fig. 2), possesses an ape-tissure, which is lying caudally from it. 
The m-+m’ suleus is thus not pushed down in the ape fissure. 
Now if we accept this m—+ mm’ sulcus (s. par. oee. lat.) to form the 
border between the lobi parietalis and occipitalis, then follows, that 
the ape fissure in these monkeys is formed on the occipital face. 
If we keep to the conception, that the plis de passage, as it is in 
semnopitheci, macaci ete, form the communication between sub- 
divisions of the brain, differing from each other (e.g. parietal and 
occipital, or temporal and occipital) then, in case the ape fissure is 
8 
Proceedings Royal Acad. Amsterdam. Vol. XIX. 
