BRAIN OF MAN AND THE BRAINS OF CERTAIN ANIMALS. 45 



internal bridging convolution, the entire absence of which from 

 the human fissure leaves it a clear void. The clear open fissure 

 in the diagram (Fig. I b, F. H.) is not the internal perpendicular 

 but the hippocampal fissure, and its large size corresponds to the 

 large hippocampus, not to the large internal occipital furrow of the 

 human brain. 



Brain then for brain, we may say that the human brain is always 

 wanting in internal, the simious very frequently in external, convo- 

 lutions for the filling up of a certain fissure which separates the 

 occipital from the parietal lobes in either case, This fact does not 

 at first seem to affect the typical meaning, or classificatory value, or 

 serial importance of the convolutions in question, though it is 

 obvious that it bears with considerable force upon their physio- 

 logical. But their serial value also is affected when we find that 

 amongst the apes, the Ateles belzebutli (the spider monkey) alone 

 of all those figured by M. Gratiolet, follows the human arrange- 

 ment, and the human relation of these four convolutions exactly, 

 as to the degradation of the one and the exaltation of the 

 other set ; in other words, in man and the spider monkey alone do 

 the external connecting convolutions come fully to the surface, 

 forming, as I have said, a quadrangular mass in man, though but 

 an hourglass-shaped mass in the monkey. Still upon such con- 

 striction as converts a quadrangular into an hourglass-shaped mass 

 there is little weight to be laid. Surely the Ateles is not so very 

 much more man-like than all other monkeys upon this ground ; 

 the imperfection denoted by its name has never been belied by 

 its manifestation of any psychical properties in correspondence 

 with its high brain, but out of correspondence with its mutilated 

 hand. 



The small area occupied by the lobes numbered 10, n, js, in 

 the human, as contrasted with that occupied by the same numbers 

 in the simious brain, speaks of a corresponding difference in their 

 occipital lobes; the mandrill has the largest occipital lobe (see 

 Fig. 3 a and Fig. 5 a), man the smallest in the series. And here the 

 doctrines of Gall may seem to coincide with the results attained by 

 quite another method, by a far more searching and truthful analysis 

 than his ; but such coincidence is but apparent. A stunted occipital 

 lobe is indeed a sign of elevation, whether we rise by giant strides 

 from species to species, or by imperceptible gradations from variety 



