( 203 ); 
I draw attention to the fact, that the sulcus calloso-marginalis on 
the mesial side of the hemisphere does not show any fragmentation; 
and that there is present a broad pH de passage between cunem and 
praecuneus. The confluency of calcarina and paneto-occipitahs, whic 
is a general feature of the human brain, and is seen only very 
rarely in the brain of the highest anthropoids, is clearly shown in 
our cause on both hemispheres. . 
On an average the homology of the furrows and circumvolutions 
present in this idiot with those of the normal surface of the human 
brain, does not present great difficulties. The greatest of them is 
the interpretation of the poorly developed occipital region. In this 
part we see at first a continuation of t, from the temporal lobe; 
further the lateral ending of the fissura calcarina coming from the 
mesial surface. Next to these sulci a transverse furrow is observed 
in the left occipital lobe, possibly corresponding with the furrow x m 
the nomenclature of Ztehen and Kukenthal ; its occipital ending mig t 
have been pushed laterad by the strong outgrowth of the calcarina 
on the convexity. 
For further details I merely refer to the explanation of the figures. 
Sometimes a more foetal, sometimes a more anthropoid type of sulci 
is seen, which mostly have a more casuistic than general importance. 
The aspect of the insulae Reilii and the neighbouring parts is ot 
greater interest. On both hemispheres the insula has remained un¬ 
covered for a large part. As has been pointed out by Bolk ) t e 
human insula and its surroundings can be understood only by the 
study of the anthropoid apes, where the sulcus opercular*is and the 
fissura fronto-orbitalis very often show a confluence. 
Only by this confluence the operculisation of the insula becomes 
possible. This phylogenesis of the covering of the insula does not 
seem to be repeated ontogenetically, not even in its principle features. 
On the contrary in man no trace is found of the fissura fronto-orbitahs, 
by the inclusion of-which in the insular space the homology of its 
frontal bifurcation with the two anterior branches of the fissura Sylvn 
would be explicable. A six-months human embryo showing on the 
convexity of its brain only the fissura Rolando, already exhibits in 
the anterior dorsal corner of the fossa Sylvii that small horizontal 
continuation, which, split up sagittally, afterwards represents both 
rami anteriores; whereas the ventrofrontal surface of the uncovere 
part 'of the insula still shows a direct continuation with the frontal 
lobe. The sagittal splitting of the above mentioned frontal continuation 
~VBeitrage zur Affenanatomie II (Orang Utan) in Petrus Camper I 1901 and YU 
(Gorilla) in Zeitschr. f. Morphol. u Anthropol. Bd. XIII 1909. 
