408 Professor Rolleston on the [Jan. 24, 



Beginning with the internal anatomy of the brains which he had to 

 compare and contrast, the speaker said that the question as between 

 man and the ape might be stated thus : — Has the ape such a biradiate, 

 two-horned ventricular cavity within its brain as has the dog, or has it 

 not rather such a one as has man himself, triradiate and three-horned ? 

 By the aid of drawings of dissected brains of the dog, of an old-world 

 and of a new-world monkey, and of man, it was seen that the interior 

 of the simious brain was even more pre-eminently a three-horned 

 cavity than was that of the human brain ; and that the new-world 

 monkey contrasted with man to even greater advantage in this, and the 

 disputed point of the closely-allied hippocampus minor, than did the 

 much more anthropomorphous old-world ape. Tiedemann's retracta- 

 tion of his error as to the processus digitati of the greater hippocampus 

 was alluded to ; the speaker insisting that though such discoveries 

 and rectifications might seem of weight and consequence to persons 

 imbued, as was Tiedemann, with materialistic views, they possessed no 

 anthropological interest whatever for the idealist. 



Certain anatomical plates of Eustachius', published some 150 years 

 ago, were shown to give representations of the interior of the human 

 brain which coincided in all points with figures of the interior of the 

 brain of the orang, which had been published within the current month 

 by two Dutch anatomists, in the English ' Natural History Review.' 



Passing, then, from the anatomy of the internal to that of the 

 external surface of the brain, the speaker said that the points of agree- 

 ment and of difference upon which he should have to dwell could be 

 arranged under two heads — either they were such as tlie eye could 

 judge of even though its owner were not an anatomist ex professo, 

 depending as they did upon general outline and configuration ; or they 

 were such as a deeply-going analysis of the convolutions alone could 

 elicit. 



Under the first head were enumerated the more elegantly ovoidal 

 and tapering shape, the more accurate semicircularity of the superior, 

 and the irregularity of the inferior boundary line, as signs of defect 

 and diminishment in the ape's brain ; but the outcropping of the 

 cerebellum from beneath the overlying cerebral hemispheres, which 

 had been so much insisted upon as a distinctive mark of the inferiority 

 of the simious encephalon, was shown to depend largely upon the 

 changes of relative position which the several masses of nervous matter, 

 comprised under the one term " encephalon," undergo when they are 

 removed from their supporting brain-case. 



The absolute necessity of comparing the configuration and propor- 

 tions of brains preserved in spirits with the configuration and propor- 

 tions of plaster-casts of the cavities they occupied during life, was 

 dwelt upon with special reference to Mr. Marshall's observations upon 

 this point in the ' Natural History Review' for July, 1861. It was in 

 the gorilla alone of the Simiadae that M. Gratiolet (' Comptes Rendus,' 

 1860, p. 803) had found the posterior cerebral lobes doing otherwise 

 than "recouvrant completement le cervelet;" and it was this peculi- 



