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is not always felt in the same way. E.g. I already pointed out that 
the centre of overgrowth can be lying more to the front or more 
to the back, and also more medially or more laterally. Moreover 
there will be still other influences, unknown to us. Result of this 
is that although in general the same aspect may be rather regularly 
found, yet this is not the case with the subdivisions. 
Accepting this, the drawing, which shows the depth of the ape- 
fissure after resecting of the operculum, can differ within certain 
limits. 
Now, when one exclusively derives from what the ape-fissure in 
adult animals shows, then one will be inclined as it were to value 
highly those curves and sulei, which are only secondarily formed. 
If we on the other hand keep to the aspect that embrology shows 
to us, then the process becomes much simpler and more com- 
prehensible. 
[f we keep to the latter, which seems rational to me, then one 
can speak in Semnopitheci and from analogy in all related monkeys, 
only of the three plis de passages as I described them. 
Now the six plis de passages, described by GratioLeT are derived 
from the three which I described and therefore they have many 
mutual characters. 
Thus Gratio.er describes three plis de passage between the 5 
suleus (s. oee. inf.) and the lateral part of m (s. par. oce. lat.). See 
fig. 3, the arrows 2 and 3. In reality one only knows my “lateral” 
pli de passage, of which a larger or smaller part is pushed into 
the ape-fissure. 
The 2>¢ + 3rd + 4th plis de passage of GRATIOLET agree with the 
“lateral” pli de passage as I described it. 
GRATIOLET moreover knows a first-outer and an upper-inner pli de 
passage,, which at a point run into one. 
From the figures 2,and 3 sub I it is to be seen, that at that point 
there is but one bridging convolution, which goes along the arcus 
par. oee. to the back of the brain. If an ape fissure should be formed, 
then this part in general is pushed for a smaller or larger portion in 
the depth. 
The 1st lateral and the upper medial plis de passage of GRATIOLET 
form therefore together the “intermedial” pli de passage, according 
to my description. 
The lower-median pli de passage of GRATIOLET, the gyrus 
of Ecker, which forms the communication between cuneus and 
praecuneus, appears in fig. 3 above the fissure calcarina (sub 4). 
This medial pli de passage remains also in the new classification 
