Ch.^p. XVI.] 



SOME OTHER MAMMALS. 



257 



as a double longitudinal commissure, its lialves, in reality 

 (after a very irregular course, the direction of which varies 

 in different animals), connect in each Cerebral Lobe, ipavts 

 that are almost situated in the same transverse plane. 

 The nature of these parts and the other relations of the 

 Fornix will be given further on (p. 272), and also in the 

 description of the corresponding structure in the human 

 brain. Its relations are of a complex order, so that its 



Fig. 70. 



Fig. 71. 



Ftg. 70. — ■Prain of Atroiiti. (Owen.) a, Medulla; 6, fourth ventricle; c, median, 

 and d, lateral lobes of Cerebellum ; e. Cerebral Hemisi^here ; /, olfactory lobes 



Fig. 71. — Brain of Beaver. (Owen.) Tlie upper parts of the Cerebral Hemispheres 

 have been fut away to the level of the 'corpus callosum,' so as to show this great 

 transverse commissure, le. Pineal body ; B, corpoia qiiadrigemina; C, cerebellum. 



fuller description will be better reserved. It is necessary, 

 however, here to state, that it mostly lies beneath the 

 ' Corpus Callosum,' and is closely connected with this great 

 transverse commissure posteriorly, though in passing for- 

 wards the tv/o structures diverge from one another. 



(4.) In the space left between the Corpus Callosum above 



