THE BRAIN. 



213 



(cerebellum). The latter is situated more posteriorly and 

 inferiorly, and shows on its outer surface equally numerous 

 furrows, which are, however, much finer and more regular, 



Fro. 220. Human brain, seen from the left side. (After H. Meyer.) The 

 furrows of the large brain are indicated by large, thick lines, those of the 

 small brain by finer lines. Below the latter the neck-marrow is visible, f-f 3 , 

 frontal convolutions ; Ce. a Ce. p, central convolutions ; B, fissure of Rolan- 

 3ns; 8, Sylvian fissure ; T, temporal or parallel fissure; Pa, parietal lobe; An, 

 the annectant convolutions ; PO, parieto-occipital fissure ; Su, supra-marginal 

 sonvolution ; IP, intra-parietal fissure ; t, temporo-sphenoidal convolution. 



and between them are curved ridges (Fig. 219, lower part). 

 The small brain is also divided into two lateral halves by a 

 longitudinal furrow; these are the "small hemispheres," 

 which are connected at the top by a worm-like cross-piece, 

 the " brain- worm " (vermis), and at the bottom by a bridge 

 (ponsvarolii; Fig. 219, VI.). 



Comparative Anatomy and Ontogeny show, however, that 

 in Man, as in all other Skulled Animals, the brain originally 

 consists not of two but of five distinct parts lying one 

 behind another. These originally appear in the embryo of alJ 



