is made in the upper margin of the hemispheres by the internal 
parieto-occipital fissure’. This objection to CuNNINGHAM’s opinion 
is absolutely right. On the other hand when KorLBRUGGE writes 
on page 223: “Darum soll man nur auf die Worte Zirney’s 
achten, dass m weder mit dem s. interparietalis noch mit der 
Fissura par. occ. medialis etwas zu schaffen habe”, he is wrong. 
We shall see later on, that the s. interparietalis and s. par. oce. 
lateralis, begin as one single fissure, so that the conception of 
CUNNINGHAM as well as that of KükENTHAT-ZiEHEN and KOHLBRUGGE 
are wrong. Also the opinion that the ape fissure begins as a fossa, 
has to be corrected. 
Working out the material’) which was at my disposal, I thought 
it useful to try to solve three yet unanswered questions. 
The first is whether the ape fissure is formed during the foetal 
life or after it. The second in what manner it commences, the 
third, where the fissura simialis has to be sought. 
Concerning the first question, it is known that the ape fissure in 
the majority of the lower primates, in the adult state, exists, but 
can be missing in a large number of cases. 
The ape-fissure too is not always equally well developed. At one 
time the whole arcus parieto-occipitalis is lost in it, at another the 
latter remains for a large part on the surface. 
In what period of life the fissura 
simialis is formed, is, as far as I 
know, not yet defined. 
The embryonic material will parti- 
ally solve this question. 
Figure I represents the brain of an 
embryo of 24 em. *) length, by a weight 
of 255 grams. In fig. Il the unborn 
monkey weighed 322 grams and mea- 
sured 25 em. In fig. HI the numbers 
were respectively 26 em. and 341 
grams. 
Knowing the length of a newly 
born semnopithecus maurus to be 
1) The material of the semnopithecus maurus embryo I had the good oppor- 
tunity to gather during the last years of my stay in Lawang (E. Java), in the 
woods on ‘the slopes of the Tenger mountains. 
*) The length is measured from the middle of the head to the commencement 
of the tail. 
1O1* 
