Cerebral Convolutions. 135 



two parts by the Fissure of the Hippocampus, which bifurcates 

 posteriorly. That portion of the Brain which is placed below this 

 Fissure, together with the Fascia Dentata (Pli Godronne, Grat.)^ 

 which does not come into view on the surface, is called the Occipito- 

 Temporal Lobe. The rest of the internal surface is again divided into 

 two by the Internal Perpendicular Fissure, which runs down from 

 the superior border of the Hemisphere and stops short about on a 

 level with the posterior extremity of the Corpus Callosum. That 

 part of the Brain which is below or behind the Internal Perpendicular 

 Fissure, and between it and the posterior part of the Hippocampal 

 Fissure is the Internal Occipital LohuU ; that above and in front of it 

 is the Fronto-parietal Lobe. 



1 . The Fronto-parietal Lobe is divided by the great Fissure of the 

 Frontoparietal Lobe into 



a. An Inferior Convolution, Convolution of the Internal Zone, s. 

 Convolution of the Corpus Callosum. h. Convolution of the External 

 Zone. 



The Convolution of the Internal Zone expands posteriorly to form 

 the Quadrilateral Lobule. 



2. In the Occipital Lobule the Convolutions are inconstant. 



3. The Occipito-Temporal lobe comprehends, 



a. The Superior Internal Temporal Convolution (Pli Godronne^ 

 Grat.), which is placed above, and externally to the so-called anterior 

 part of the Hippocampal Fissure and does not appear on the surface : 



h. The Middle Internal Temporal, placed below the Hippocampal, 

 and above the Collateral Sulcus of Huxley. This convolution ends 

 anteriorly in a large Lobule lobule of the Hippocampal Convolution 

 (lobule de I'Hippocampe, Grat.)^ and from the extremity of this 

 lobule a little hooked process curves backwards, which is the Hook 

 of the Hippocampal Convolution (Crochet de I'Hippocampe, Grat.) : 



c. The Inferior Internal Temporal which consists of parts of three 

 Convolutions which also take part in the formation of the External 

 surface of the Hemisphere ; viz. the Inferior External Temporal, 

 Inferior External Occipital, and the Middle External Occipital 

 Convolutions. 



Two Bridging Convolutions also belong to the Internal Surface. 

 They connect the Quadrilateral with the Occipital Lobule, and are 

 sometimes superficially sometimes deeply placed. They are the 

 Superior Internal Bridging Convolution which passes from the summit 



