328 



AN INTRODUCTION TO ZOOLOGY 



and Rana are also to be found in Lepus, but the relative size of the 

 paits is very different, so that the brains as a whole are very dis- 

 similar in external appearance. Perhaps the most striking difference 

 is the enormous development of the cerebral hemispheres in Lepus, 

 where they form a large part of the total mass of the whole brain. 

 There is no doubt that mammals owe their dominant position in 



OL 



FL 



Oc 



sc 



FIG. 112. Brain of Lepus. Dorsal view. 



A.C., anterior quadrigeminal body ; C.H., cerebral hemisphere ; F., flocculus ; F.L., frontal 

 lobe ; M., medulla ; Oc., occipital lobe ; O.L., olfactory lobe ; P., paraflocculus ; P.C., posterior 

 quadrigeminal body ; P.L., parietal lobe ; S.C., spinal cord ; S.F., sagittal fissure ; T.L., temporal 

 lobe ; V., vermis. 



tke animal kingdom to-day to the large development of this region 

 of the brain and the increase in intelligence that accompanies it. 



The front end of the brain, the telencephalon, is expanded 

 into the large cerebral hemispheres which form the anterior two- 

 thirds of the brain and may be spoken of together under the inclusive 

 term cerebrum. Both from the dorsal and lateral aspects they 



