THE LOWER VERTEBRATA. 



151 



encephalon and mid-brain are fully exposed in dorsal view 

 instead of being hidden by the cerebral hemispheres and 

 cerebellum. The hemispheres (or cerebral lobes, as they 



IT 



O/Tft TAACr 



Fig. 75. BRAIN OP FROO. 

 Side view. (After Wiedershelm.) 



are usually called) are comparatively small, and have large 

 ventricles; their commissures are far fewer than in the 



A B 



Fig. 76. BRAIN OF FROG. 



A, Dorsal, B, Ventral view. (After Wiederaheim.) 



rabbit, for there is no corpus callosum nor middle com- 

 missure, though the anterior and posterior commissures are 

 present. The olfactory lobes are united in the median line. 



