223 
removed so far, that they, as it were, come to be lying in another 
sulcus. 
In short to mention an example, KounLBruGGe *) writes on page 70 
“Auf XXI und XXII liegt der Diagonalis in der Tiefe, eingebettet 
in den vorderen Rand des s. praec. inf.” 
In semnopitheci and macaci it is different: there one finds the 
m-+m' suleus (par. oec. lat. seu oce. transversus) on the surface. 
In case there is an ape fissure then that total sulcus, the caudal 
part of the / 4e sulcus (s. interparietalis) included is pushed in a 
newly arisen sulcus. 
If one opens the fissure, one always finds the 1 + m! suleus in 
it. This is quite distinctly indicated in fig. Il of ZuckerKANp1’s ° 
communication. 
Such striking proofs for the recognition of an ape fissure are missed 
in the communications of Eruor Smita and Murpny'’), so that I am 
justified in accepting that they did not find this proof present. 
The secon! characteristic one could find in the “plis de passage”. 
I pointed out’) that the ““plis de passage” primarily are lying on 
the surface and only secondarily are pushed down to the depth. 
Now it is not always very easy to make out whether a part of 
the cortex, which one finds in the depth is lying under normal 
circumstances on the surface. Yet it is comprehensible that under 
certain circumstances this can be possible, as we have seen in ape 
embryos. 
Kiiior Smita does not make use of these “plis de passage” to 
demonstrate, that his sulcus lunatus is an ape-fissure. 
The third characteristic could be sought in the localisation of 
the fissure. 
In a former communication’) [ came to the conclusion, that the 
ape-fissure developed through augmented growth of the lobus occipi- 
talis. As this will take place in apes of the same species always in 
nearly the same way, therefore too the ape fissure in the same species 
of apes will be formed on nearly the same place. One can under- 
stand, that when in men a {rue operculum is formed on the lobus 
occipitalis, this always must be found at nearly the same distance 
from neighbouring sulci. 
Errror Situ describes to us the localisation of his sulcus lunatus 
on page 448 in this way: 
“The sulcus lunatus is subjected to a very wide range of variation 
in the human brain... The sulcus lunatus may extend right across 
the lateral aspect of the hemisphere from the dorso-mesial to the 
ventro-lateral edge, as in most chimpansees. It may be a much 
