48 xHteT NEEYOTJS SYSTEM. 



a in a direct ratio with that of the hemispheres, 

 as is also the pons Varolii with that of the late- 

 ral lobes of the cerebellum. 



In the monkeys, as the Cercopithecus sabceus, 

 the brain (figs. 32 and 33) evidently resembles 

 that of man in its general configuration. The 

 hemispheres (fig. 33, a, a', a") are well deve- 

 31. loped, both in their anterior and posterior lobes; 

 the latter almost cover the cerebellum (in fig. 

 33, c, c) ; they are relatively of large size, and 

 have weU-developed lateral lobes (fig. 32). The 

 medulla oblongata, d, is large, and presents the 

 pyramidal olivary, and restiform eminences, 

 as in man. The internal structure of the brain 

 of this monkey is seen at fig. 32, where a is 

 the corpus callosum ; b } the anterior commis- 

 sure; c, corpora striata; d, optic thalami ; e, the 

 radiated disposition of the medullary fibres, as 

 they pass through the thalami and striated bo- 

 dies ; /, the pineal gland ; g, the anterior tu- 

 bercles ; h, the posterior tubercles, nates, and 

 testes, of the corpora quadrigemina ; i, the 

 posterior termination of the lateral ventricle ; 

 I, the fourth ventricle ; m, the medulla oblon- 

 gata ; n, the lateral lobes of the cerebellum, 

 divided to show the arbor vitse. 



Fig. 33 is the base of the same brain : 1, the 

 olfactory nerves ; 2, the optic nerves ; 3, the 

 third ; 4, the fourth ; 6, the sixth pairs of 

 nerves : a, the anterior ; a', the middle ; a", the 

 posterior lobes of the hemispheres ; c, the cere- 

 bellum; c 1 ', the pons Varolii. The corpora albi- 

 cantia form a single projection behind the in- 

 fundibulum; the olfactory nerves have no mam- 

 millary swelling like the olfactory of man ; the 

 posterior cornu of the lateral ventricles, and 

 the pes hippocampi, are wanting. The brain of 

 the ourang, and particularly that of the chim- 

 pansee, bear a still closer resemblance to that 

 of man : the hemispheres are more largely deve- 

 loped, the convolutions more numerous and 



