LOBES AXD GYRI OF THE CONVEX SURFACE. 69 



the occipital lobe a variable distance (Fig. 20). It is not always 

 continuous with the horizontal limb. Running about an inch 

 from the supero-medial border of the hemisphere, it passes the 

 occipito-parietal sulcus, from which it is separated by the arcus 

 occipilo-parietalis, and bifurcates in the superior occipital gyrus 

 into two more or less oblique branches, constituting the trans- 

 verse occipital sulcus. The medial end of the transverse sulcus 

 may or may not cut the supero-medial border of the lobe. 



The lateral occipital gyrus (Figs. 20 and 24) lies below the 

 lateral occipital sulcus and extends from the occipital pole forward 

 along the infero-lateral border of the hemisphere to the preoccip- 

 ital notch. Sometimes it is divided into two lateral gyri by an 

 inferior lateral sulcus. It is continuous with the inferior tem- 

 poral gyrus, except rarely, when the two are separated by the 

 external perpendicular sulcus. 



The superior occipital gyrus forms the upper half of the 

 convex surface of the lobe (Figs. 20 and 24). It is incompletely 

 separated from the lateral occipital gyrus by the lateral occipital 

 sulcus and is often divided into two gyri. It is continuous with 

 the post-parietal gyrus around the lateral end of the transverse 

 occipital sulcus; and, around the medial end of that sulcus, it 

 is joined to the superior parietal lobule by the arcus occipito- 

 parietalis. The latter is a sharply curved annectant gyrus which 

 bounds the occipito-parietal sulcus. When the middle temporal 

 sulcus does not turn upward at its posterior end and terminate 

 in the parietal lobe, the superior occipital gyrus is continuous 

 in front with the middle temporal and angular gyri. As already 

 mentioned, the superior occipital gyrus, according to Mills, 

 belongs to the center for visual memories. 



(4) The temporal lobe (lobus temporalis, Figs. 20, 22, 23, 24, 

 25 and 26) is that part of the cerebral hemisphere behind the 

 main stem and below the posterior limb of the lateral cerebral 

 fissure. It rests in the middle fossa of the skull; forms the 

 temporal pole of the hemisphere; and is continuous posteriorly 

 with the occipital and parietal lobes, from which it is marked 

 off only by the imaginary lines already described. On the basal 

 surface of the hemisphere, the temporal lobe along its medial 



