REPORT ON THE SEALS. 107 



connected the hippocampal gyrus with the Sylvian and suprasylvian convolutions ; the 

 ascending part of this fissure ran backwards behind the splenium, and then curved 

 upwards and forwards so as to get above it ; here it was interrupted by a bridging con- 

 volution, beyond which it was continued horizontally forwards above and parallel to the 

 corpus callosum, but separated from it by the callosal convolution ; it ended anteriorly 

 in two branches, both of which reached the margin of the hemisphere, the one ended a 

 little above the inner end of the crucial fissure, but the other was continuous with the 

 crucial fissure itself. Behind and below the end of the splenium the splenial fissure gave 

 off a postero-horizontal fissure (ph), which, running horizontally backwards, extended 

 almost to the posterior border of the hemisphere. Immediately in front of the 

 interrupting convolution an offshoot of the splenial fissure was prolonged upwards and 

 slightly backwards to the sagittal margin of the hemisphere. 



In the other well-grown brain, the part of the splenial fissure in relation to the hippo- 

 campal gyrus was interrupted by two bridging convolutions in the left hemisphere, but 

 by only one in the right. The part above the callosal convolution was not interrupted by 

 a bridging convolution in the left hemisphere, though it was so in the right. In both 

 hemispheres this fissure terminated anteriorly by becoming continuous with the inner 

 end of the crucial fissure. In both hemispheres, also, a postero-horizontal fissure (ph) 

 extended backwards from the splenial fissure almost to the posterior border of the 

 hemisphere (PL X. fig. 5). 



The hippocampal fissure (h) was situated above the hippocampal gyrus, between it 

 and the taenia hippocampi ; it curved round the splenium, and became continuous with 

 the callosal fissure ; at the bottom of this fissure, between it and the taenia hippocampi, 

 was the dentate gyrus. 



The great arched convolution, gyrus fornicatus or the great limbic lobe of Broca, 

 was differentiated by the splenial, hippocampal, and callosal fissures, and consisted of 

 callosal and hippocampal convolutions with the uncinate gyrus or lobus hippocampi. 

 The lobus hippocampi (Hi) was the inferior end of the hippocampal convolution, and formed 

 the inner portion of the posterior lip of the Sylvian fossa ; it was demarcated on its outer 

 lateral side by the postrhinal fissure (pr) which was continued forwards into the Sylvian 

 fissure, to become through it continuous with the rhinal fissure ; the tuber olfactorium 

 was also continuous with the uncinate gyrus, but the intermediate band was small and 

 so deeply lodged in the Sylvian fissure as to be recognised with some difficulty. The 

 recurved part of the lobus hippocampi was continuous with the taenia hippocampi and 

 with the band of grey matter at the bottom of the hippocampal fissure which in human 

 anatomy is called fascia dentata or dentate gyrus. The hippocampal gyrus (he) was 

 prolonged from the uncinate gyrus backwards and upwards, and was marked by shallow 

 arterial depressions similar to those described in the Elephant Seal. The ccdlosal gyrus (cc) 

 at first passed horizontally forwards and then bent downwards in front of the genu of 



