448 



So far as I am aware, M. and Mde. Dejerine are the only writers 

 who have accurately represented the distribution of the area striata 

 on the mesial surface of the human brain ^), and its correct relationship 

 to the sulcus praestriatus (calcarinus proprius) and the s. intrastriatus 

 (retrocalcarinus). In the first volume of the same work this relation- 

 ship to the sulcus calcarinus (praestriatus) is also clearly demonstrated 

 (see Fig. 223, p. 398; 224, p. 402; 228, p. 414; and 229, p. 418): 

 and in the same volume the characteristic relationship to the sulcus 

 lunatus ("Affenspalte") — labelled i. o. (sillon inter -occipital) in the 

 Dejerine's book — is clearly demonstrated: — Fig. 228, p. 414 and 

 Fig. 229, p. 418. 



In many of their other Figures the lateral part of the stria Gen- 

 nari is represented as being prolonged much too far forward, as a 

 comparison with their own correct Figures (228 and 229) and my 

 Figure 4 shows. The stria Gennari often fails to extend quite so far 

 forward as the posterior lip of the sulcus lunatus but although I have 

 examined more than 400 hemispheres I have never seen it extend 

 further forward in the manner represented in many of the figures in 

 the great treatise written by M. and Mde. Dejerine. 



The evidence afforded by the distribution of the stria Gennari 

 absolutely demonstrates the correctness of the homology which in my 

 former note I instituted between the sulcus lunatus in the human brain 

 and the so-called "Affenspalte" of the Apes, 



The sulcus lunatus is subject to a very wide range of variation 

 in the human brain. I have examined it in more than four hundred 

 brains and have never seen it exactly symmetrically disposed in the 

 two hemispheres of one brain. In the majority of cases (in Egyptian 

 and Soudanese brains) its posterior lip is opercular. But it may be 

 a simple incision ; and frequently some adjacent sulcus, especially the 

 sulcus occ. transversus, may have a caudal opercular lip which simu- 

 lates the true stria -bearing occipital operculum. 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 Chimpanzees. It 

 may be a much shorter furrow placed anywhere between these two 

 extremes. It may be transverse, oblique or horizontal in direction. 

 It is very frequently interrupted by ;a submerged "gyrus translunatus": 

 and occasionally this gyrus comes to the surface and completely divides 

 the lunate sulcus into a pars dorsalis and a pars ventralis. Either of 

 these furrows may be joined to a sulcus praelunatus so as to form a 

 pattern, which is at first sight somen tral perplexing. 



1) Anatomie des Centres Nerveux, T. 2, 1901, p. 240. 



