Chap. XXL] OF THE HUMAN BRAIN. 389 



found to be distinctly posterior to the median axis. The "brain of 

 the eminent mathematician Dirichlet is longer and broader than, 

 either of the others tigured by Wagner. Its posterior extremity 

 is narrower than the anterior, and even notably pointed. Its 

 greatest breadth may be seen to be only slightly posterior to its 

 median axis, and to correspond with the hinder part of the ascend- 

 ing parietal convolution. 



Notable variations are therefore to be met with in the 

 shape of the Brain as seen from above, as might have 

 been expected from a consideration of the diverse shapes 

 of the human Skull in dilBferent races and individuals. We 



Ftg. 142.— Brain of Gauss, the Celebrated Mathematician and Astronomer, side 

 view. (Vogt, after R. Wagner.) 



F, Frontal lobe ; P, parietal lobe ; 0, occipital lobe ; T, temporal lobe ; C, cere- 

 bellum ; Po, pons Varolii ; V M, medulla oblongata ; S, Sylvian fissure ; R, fissure of 

 Rolaudo; P >, parallel fissure, a', Upper fold of frontal convolutions ; a"^, middle 

 fold of frontal convolutions ; a^, lower fold of frontal convolutions. A, Ascending 

 frontal (or anterior central) convolution ; B, ascending parietal (or posterior central) 

 convolution ; 6', b^, b^, upper, middle, and lower folds of parietal convolutions ; 

 c', c2, c:', upper, middle, and lower folds of temporal convolutions; ci', ^2^ cj3^ upper, 

 middle, and lower folds of occipital convolutions. 



have extreme ' long-heads,' and extreme ' round heads,' 

 interspersed with multitudes of individuals whose cranial 

 diameters are more nearly equal. On the whole, it is, 



