1042 
show the beginning of apparent return to lower relations, because 
part of the transition-convolutions (the first) has become superficial. 
It is however still separated by the sule. interparietalis from the 
superficial part of the 2°¢ transition-convolution. A similar situation 
was to be found in the microcephalic idiot described by me in a 
former paper (I. c.). If now moreover the 2°¢ and 3'¢ transition- 
convolutions become superficial i.e, if they pass from the bottom of 
the monkey-slit to the surface of the lob. parietalis, then of the 
entire s. simialis-complex there remains only the bottom-suleus which 
is then, with regard to its parietal lip, differently limited from what was 
the case with anthropoides, at least as regards the region of the 
2nd and 3° transition-convolution. This is however not always the 
case. Also where there is no question of great disturbances of 
development, as in the above-cited case of mikrocephalia, little hidden 
convolutions may be found (vide e. g. some drawings in ZUCKERKANDL’S 
paper |. ¢.). Such brains connect the monkey-slit in a more limited 
sense —- as it occurs in anthropoides — with the suleus lunatus 
(as with Errror Smirn we best call it) of man. About the frequency 
of the occurrence of this sulcus in Europeans I cannot fix a per- 
centage on account of my limited material. 
In 22 hemispheres of idiots of the Institute for Brain-research | 
find it 8 times. In the brain of normal individuals it likewise “often” 
occurs. ErLIOT SMITH fixed already the attention to the brain-photographs 
of Rerzus. I could not decide with certainty whether, as it seems 
to be Error Smirn’s view, there exists any preference in this 
respect for the left hemisphere. 
Notwithstanding all these assertions it is necessary to fix as 
strongly as possible the diagnosis: suleus lunatus. One cannot give 
a definition of it of absolute value, i.e. without involving in it 
the relation to neighbouring sulci. As conditions for accepting a 
sulcus lunatus I fixed in general the following relations and circum- 
stances: 
1. The suleus in question lies somewhat crescentshaped (with 
its concavity caudad) or more transversal, not far from the pole of 
the occipital lobe ; 
2. In its lateral part terminates a sulcus, that is often connected 
with the first temporal sulcus (sulcus praelunatus) ; 
8. More or less parallel to it, more towards the front, lies a 
