111 
In my former publication I made clear, that when in semnopi- 
theci the ape-fissure is being formed, (result of the overgrowth of 
the occipital part), the line of curvature begins either caudal or 
nasal of the m + m’. In the schematic drawing (fig. 3), | granted, 
that this line of curvature (see dotted line) is lying caudal of the 
mm’, and therefore when the ape-fissure is later being formed, 
the three /+e, m—+m’ and w have to be found on the frontal 
face of it. 
As the ape-fissure generally extends from a point on the lateral 
surface, mostly medially from 5, (s. oee. inf.) and from there over 
the ridge of the mantle towards the medial face and there is united 
with the ventral part of w (s. par. oee. med.), the following will 
happen with the three plis de passage (see dotted line fig. 3). 
The “lateral” on fig. 3 indicated by the arrows 2 and 3, will 
disappear for a part e.g. y in the ape-fissure. The part 2 however 
will remain on the surface. Only in case the ape-fissure is extended 
unto the 4 suleus, then too the part 2 will disappear in the depth. 
Such a case ZUCKERKANDL describes on page 286 in cynocephalus 
marmon and cercopithecus patas. 
The ‘intermedial’ communication, indicated on fi 
arrow 1 will disappear partly or wholly in the depth. 
The ‘medial’ pli de passage, indicated on fig. 3 by the arrow 4 
will never disappear in the depth, because till now, as to my 
knowledge, no ape-fissures have been described, which pass on to 
the fissura calcarina. | 
The above mentioned, which is a logical result of what the 
development of the ape-fissure teaches us, is not in accordance with 
the conception of GrationeT and others, that the number of the plis 
de passage should be six and of these 4 on the lateral and 2 on 
the medial face. | 
The cause of the difference of opinion has to be looked for in 
the starting-point of the investigation. 
I from my point of view, believe that in this case should prevail 
what embryology teaches us, while GrATIOLET started from that 
which he found in adult specimens. 
Now it is comprehensible that when an ape-fissure is going to be 
formed and during this process the fore part is-pushed downwards, 
this cannot always happen equally regularly. Therefore it is natural, 
that. after opening the ape-fissure not always the same aspect will 
be shown to us. During the downwards pushing there will be 
formed curves, plis and sulci, which will not always obtain the 
same form. The sooner this will not be the case where the influence 
3 by the 
O° 
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