574 



Nachdruck verboten. 



On the Asymmetry of the caudal Poles of the Cerebral Hemi- 

 spheres and its Influence on the Occipital Bone. 



By G. Elliot Smith, Cairo. 

 With 3 Figures. 



It is a well-known fact that the sinus longitudinalis superior is 

 directly continued into the right lateral sinus in the majority of cases 

 in Europeans ^) and as the result the right lateral sinus and its groove 

 on the occipital bone are larger than those of the left side. It is not 

 so commonly recognised that there is also a marked asymmetry of the 

 squama occipitalis, the left side being as a rule much more prominent 

 than the right 2). I am not aware that anyone (except the present 

 writer) has published any exact record of the asymmetry that is com- 

 monly found in the conformation of the occipital region of the human; 

 brain. 



Some years ago I noticed the fact that the left occipital regiom 

 of the human brain exhibited a much closer resemblance to the Simian 

 type than the right in the vast majority of cases (roughly about 80** 

 of Egyptian — non-negroid — brains). 



On enquiring further into this matter I found that in most cases, 

 the area striata — i. e. the area of cortex containing Gennari's stria 

 — extended much further out on to the outer aspect of the left 

 hemisphere than on to the corresponding surface of the right hemi- 

 sphere (Fig. 1). In the attempt to explain this I put forward the 

 suggestion — which subsequent investigation has shown to be er- 

 roneous — that probably the left area striata is more extensive than 

 the right ^). 



Last year I took a number of fresh brains and excised the whole 



1) Le Double, Traits des Variations des Os du Crane, 1903, p. 16. 

 — In 200 cases the superior sinus turned to the right in 137 and 

 to the left in 29 and in the rest some other arrangement was found. 

 RüDiNGER found it continuous with the right in 70 cases out of a 

 hundred. 



2) Tedeschi, Studi sulla simmetria del Cranio. Atti della Societä 

 Romana di Antropologia, Vol. 4, 1897, No. 2 and 3. 



3) Studies in the Morphology of the Human Brain. Records of the 

 Egyptian Government School of Medicine, Vol. 2, 1904, p. 169. 



