64 



Prof. G. Elliot Smith. The Morphology of [Dec. 1, 



reference to a more detailed account of its distribution. In most of 

 the brains of Apes that I have examined, the area striata extended 

 forward on the surface of the operculum, but often failed to reach 

 as far as its anterior free margin ; in some cases it ceased abruptly 

 at a point 4 or 5 mm. behind the edge of the operculum. In the 

 Cercopithecidaa (in which the operculum is relatively biggest) the stria 

 Genii ari extended upward as far as the dorso-mesial edge of the 

 hemisphere, and laterally (or ventrally) as far as the sulcus occipitalis 

 inferior. The sulcus occipitalis superior lies in the midst of the area 



Fig. 2. — Horizontal Section through the Posterior Parr of the right Cerebral 

 Hemisphere of an Egyptian. 



r = Sulcus retrocalcarinus. 



The thick line represents the stria Grennari. It is quite exceptional for the sulcus 

 collateralis to he prolonged into the area striata as in this diagram. 



striata. Thus, if the whole stria-bearing cortical region were spread 

 out in one plane, it would present a racquet-like shape — the handle of 

 the racquet corresponding to the retrocalcarine cortex and the 

 expanded part to the occipital operculum. In the Human brain the 

 " handle of the racquet " becomes greatly enlarged at the expense of 

 the rest of the area striata. But its form is subject to a very wide 

 range of variation, which I shall describe in detail in a forthcoming 

 memoir. 



[Addendum, January 11. — The so-called "calcarine fissure" in the 

 Apes is a complete involution of the whole of the mesial part of the 

 area striata. The so-called " calcarine fissure " (of most writers) in 



