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PROF. HUXLEY ON THE 



[June 11, 



the posterior thickening of the corpus callosum, opposite x, it rapidly 

 deepens as it is traced backwards, and forms a great fissure, extending, 

 in some parts, for as much as f of an inch upwards and outwards, 

 and passing backwards until it nearly reaches the posterior margin 

 of the hemisphere, where it terminates by dividing into two short, but 

 deep, branches, a superior and an inferior. Traced from before back- 



occ 



occ - 



Fig. 2. — View of the inner surface of the left cerebral hemisphere of Ateles, of the 

 natural size, and beneath it a corresponding view of the human left cerebral 

 hemisphere reduced to the same size. In the latter only the principal sulci 

 are indicated, i. calloso-margtnal sulcus ; k. occipito-parietal sulcus ; /. cal- 

 carine sulcus ; m. dentate sulcus ; n. collateral sulcus ; x. continuation of 

 the callosal gyrus (18) into the uncinate gyrus (19). A, B, C, &'c., A', B', C, 

 &.C., the lines along which the transverse sections in Fig. 1 are taken. 



