445 



nearly homologous to the "posterior calcarine" seeing that both are 

 intrastriate (compare Fig, 5 and 8). The anterior prolongation of the 

 so-called "calcarine fissure" of the Apes does not pursue a course 

 along the boundary between the area striata and the gyrus fornicatus 

 (as the sulcus in the human brain does [Fig. 9]), but it cuts hori- 

 zontally into the latter. The case is rendered more complicated by 

 the fact that it sometimes happens that the so-called "calcarine" sulcus 

 of the human brain conforms to the Simian type, i. e. there is a for- 

 ward prolongation of the sulcus intrastriatus and no sulcus praestriatus 

 (true calcarine). In the brain of a Soudanese Negro I have seen a 

 sulcus praestriatus submerged in the forward prolongation of a sulcus 

 intrastriatus such as I have described in Cercopithecus (Fig. 7). 



In most Cebidae (excepting the genera Lagothrix and Ateles) 

 and in the smallest Cercopithecidae (most examples of Cercopithecus 

 and many of Macacus) the lateral part of the area striata is smooth. 

 Its anterior boundary is represented by the anterior margin of the 

 occipital operculum and its inferior limit by a "sulcus infrastriatus" 

 (the sulcus occipitalis inferior [Wernicke] of my previous memoirs, 

 the sulcus occipito- temporalis lateralis^), the sulcus occipitalis lateralis 



of ZUCKERKANDL 2)) 



In most of the Cercopithecidae (especially in Cercopithecus, Ma- 

 cacus, Cynopithecus and Papio) the dorsal lip of this sulcus infra- 

 striatus forms an operculum the superficial layer of which is composed 

 of area striata. So that (as in the case of the occipital operculum 

 and the sulcus lunatus) the edge of the stria-bearing cortex is sepa- 

 rated from the floor of the sulcus by the breadth of the operculum. 



In many human brains, when the "retraction" of the area striata 

 brings its greater part on to the mesial surface a portion of the homo- 

 logue of the infrastriate sulcus lies on the inner face of the hemisphere: 

 this furrow is often overlapped by a distinct operculum like that of 

 its laterally-placed homologue in the Apes. 



In the genus Cercopithecus a faint longitudinal furrow is usually 

 present within the lateral area striata in the larger species: in Ma- 

 cacus this furrow is often more distinct : in Papio (as a rule) and con- 

 stantly in Semnopithecus and all the Simiidae a definite "sulcus intra- 

 striatus lateralis" (the sulcus occipitalis superior of my earlier note 

 in this Anzeiger, the "sulcus occipitalis" of Zuckerkandl and Kohl- 



1) Kohlbrügge, Zeitschr. f. Morphol. u. Anthropol. (herausg. v. 

 Prof. Dr. G. Schwalbe), Bd. 6, 1903, Heft 2, p. 231. 



2) Arbeiten aus dem Neurolog. Institut an der Wiener Universität 

 (herausg. v. Prof. Dr. H. Obersteinee), 1904, Heft 10, p. 45. 



