xiii 



PHYLtJM CEtORDATA 



465 



strand of longitudinal fibres, which bifurcates both anteriorly and 

 posteriorly to form the so-called pillars of the fornix anterior 

 (Figs. 1106 and 1107, a. fo), and posterior (Fig. 1106, p. fo.). 

 Below the corpus callosum, between it and the fornix, the thin inner 

 walls of the hemispheres (septum lucidum, sp. lu.) enclose a small, 



f*. 



J.p. - 



-ii 



n 



xn 



FIG. 1105. Lepus cuniculus. Brain. A, dorsal, B, ventral, C, lateral view. b.o. olfac- 

 tory bulb ; cb'. median lobe of cerebellum (vermis) ; cb". lateral lobe of cerebellum ; cr. 

 crura cerebri ; ep. epiphysis ;f.b. parencephala ;f.p. longitudinal fissure ; h. b. cerebellum ; 

 hp. hypophysis ; m.b. mid-brain (corpora quadrigemina) ; md. medulla oblongata ; pv. 

 pons Varolii, the transverse fibres of which are here not indicated ; i-xii, cerebral nerves. 

 (From Wiedersheim.) 



laterally compressed cavity, the so -called//^ ventricle or pseudocode, 

 this is not a true brain-ventricle, but merely a space between the 

 closely-apposed hemispheres. 



The lateral ventricles of the cerebral hemispheres are much more 

 extensively developed than in the brain of the Pigeon, and of some- 

 what complex shape. Each consists of a middle portion or body 



