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crosses the bottom of the ape-fissure 
and continues on the hind surface. 
The difference between fig. 12 and 
14 is distinct and speaks for itself. 
KOHLBRUGGE too has seen the conti- 
nuation of sulci on the hind surface 
of the ape-fissure, and on page 223 
he writes: “dann sieht man wie die 
m Furehe schräg in das Operculum 
einschneidet”. On page 221 he also 
points out, that the first “pli de 
passage” can continue on the oper- 
Fig. 14. 
culum. 
Fig 13 demonstrates to us just the reverse of that which is 
found on fig. 11, i.e. that a part — the caudal part through the 
parietal lobe — is found on 13 on the kind surface, on the other 
hand on 11 on the front surface of the ape-fissure. 
Between these forms naturally there exist all sorts of transitions. 
E.g. fig. 10 of my collection shows likewise a macacus in the 
intermedial state of development in which the m + m’ suleus lies 
on the same level as the bottom of the ape-fissure. The front 
surface is totally formed by the parietal, the hind surface by the 
occipital lobe. 
The examples, which 1 gave, prove that although in monkeys of 
the same sort, with a well-developed m +m’ sulcus, the ape-fissure 
may be formed on that spot, yet by no means always the same part 
of the brain-mantle is pushed downwards. 
If we accept the consequences of this latter, then we must accept, 
that when in other monkey species the relations alter, then too 
the ape-fissure can be formed at other places. 
If my conception in this case is right, then this above-mentioned 
has to be proved by investigations of others. 
Van VALKENBURG*) Communicates, that in some platyrrhines (ateles) 
the S-interparietalis ends in a T piece, possibly therefore the m + m’ 
suleus and that this piece does not end in, but before a sulcus, 
which he and others take for the ape-fissure. This sulcus has a 
type. differing from that in semnopitheci, macaci and others, as 
the sulcus interparietalis is yet present, but does not end in the ape- 
fissure. Var VALKENBURG moreover points out, that although this 
1) Van VALKENBURG, On the appearance of the ape-fissure in man. Communi- 
action Royal Academy of Science 19 Febr. 1913. 
