MAB SHALL O^ THE BBATN OF A YOUNG CHIMPANZEE. 309 



named the supci'ior temporal or marginal, 7,7, the middle temporal, 8,8, and the 

 inferior temporal, 9. The convolution of the hippocampus major is marked * in 

 fig, 2. The Island of Reil has five shallow convolutions.] 



" We have already stated that the occipital lobe, o, is very large. It presents 

 several parallel sulci, amongst which the one which separates the middle occipital 

 convolution, 11, from the superior occipital convolution, 10,10', predominates. The 

 operculum, [viz. the border in front of 10,10'], is entire and well developed. 



" But the chief ground of distinction between the brains of the Chimpanzee and 

 Orang is the absence [in the Chimpanzee] of the superior connecting convolution 

 (le premier pli de passage). 



" Thus, the first or superior connecting convolution is absolutely wanting. 

 [This, if present, would pass across the operculum opposite to 10, fig. 5]. 



" Hie second connecting convolution is hidden under the operculum. [This lies 

 opposite to 10']. 



" The third, fig. 4, c, and fourth, d, connecting convolutions are superficial." 



Prom the foregoing quotations, it will be seen that the arrange- 

 ment of the convolutions in our specimen, coincides remarkably 

 with the description of M. Gratiolet. It must be noted, however, 

 that all those on the vertex, are considerably hroader and flatter than 

 in the restored figure given by that author ; but they resemble in 

 this respect, very strikingly, those represented in Schroeder van 

 der Kolk's and Vrolik's plate. This flatness, evidently the result of 

 pressure, affords a special confirmation of the view that the brain 

 figured by the Dutch anatomists, like our own specimen, had been 

 deformed during its preservation. 



Of the convolutional characters which, in M. Gratiolet's opinion, 

 distinguish the Chimpanzee, viz., the great size of the occipital lobe, 

 the neatness of definition of its operculum, the mode of origin of the 

 bent convolution, the absence of the first connecting convolution, 

 and the hidden position of the second, all are strictly fulfilled upon 

 the left cerebral hemisphere of our specimen ; but, on the right or 

 dissected side, of which a photograph is preserved, there was a rudi- 

 mentary superior connecting convolution, of very small size, passing 

 from the outer margin of the lobule of the second ascending convo- 

 lution, outwards, and then, bending inwards and backwards, across the 

 perpendicular fissure, to join the occipital lobe. The presence of this 

 superior connecting convolution in the Chimpanzee, and on one side 

 only, is another example of that variety and want of symmetry, as 

 regards these connecting convolutions, noticed by Dr. Eolleston in 

 his interesting paper (p. 212). Nevertheless, vary as they may, the 

 several connecting convolutions are evidently, as M. Gratiolet 

 first pointed out, the traces, or homologues, of much more highly de- 

 veloped, but corresponding, parts of the Brain in man. On the whole, 

 too. the evidence is still in favour of this particular connecting con- 

 volution being less developed in the Chimpanzee, than in the Orang. 

 As to the second connecting convolution, it existed on both sides of 

 the Chimpanzee's brain, concealed under the operculum, but of good 

 size. In reference to what M. Gratiolet describes as a very remark- 

 able feature in the Chimpanzee's brain, viz., the broad origin of the 

 bent convolution (pli courbe) in front of the top of the Sylvian fis- 



