584 
Proceedings of the Eoyal Society 
and posterior lips of the combined Sylvian and parallel fissures. The 
remarkable superficial continuity of these fissures might be apt, on 
a hasty glance, to lead to the impression that the Sylvian fissure 
mounted much higher on the outer surface of the hemispheres than 
is usual, but what at first sight seemed to be the upper end of the 
Sylvian was really the upper end of the parallel fissure, as was at 
once proved by separating the ascending and descending parts of 
the bent convolution from each other, when the upper concealed 
end of the Sylvian fissure became visible. A similar arrangement 
to that just described has been stated by Glratiolet (p. 29) some- 
times to occur in the brain of Cercopithecus Sabceus. 
The median or central lobe (Island of Eeil) consisted on the left 
side of five short and almost straight convolutions, none of which 
possessed any great size, but on the right side only four were 
visible. The fissures which separated these gyri from each other 
were short and shallow. The gyri radiated outwards and back- 
wards from the locus perforatus anticus. The most anterior joined 
superficially the inferior frontal gyrus ; the rest were separated by 
Fig. 3. — View of the inner face and postero-inferior surface of the Brain In my ex- 
planation of the arrangement of the sulci and gyi’i of the inner face of the hemisphere, I have 
adopted the tenns with the letters and numerals employed hy Mr Huxley in his “ Memoir on 
Ateles Paniscus" (Proc. Zoological Soc. 1861), and hy Mr Flower, in his “ Memoir on the 
Posterior Lobes of the Cerebrum, in the Quadrumana” (Phil. Trans. 1862). 
a deep groove from the convolutions, which formed the anterior lip 
of the Sylvian fissure. The island was deeply situated within the 
