MAMMALIA 



317 



mammals. The vocal organs are in the upper part of the trachea 

 instead of the lower, as in birds. 



Fig. 259. — a, Brain of rabbit, from above; the roof of the right hemi- 

 sphere is removed so as to exjiose the lateral ventricle; }>, the same from 

 below; c, brain of cat; on the right side the lateral and posterior part of the 

 hemisphere is removed, and almost as much on the left side, and the greater 

 part of the hemispheres of the cerebellum have been removed ; d, brain of 

 orang (a, b, c, after Gegenbaur; d, from the regne animal): Vh, Cerebral 

 hemispheres; Mh, corpus quadrigeminum; Cb, cerebellum; Mo, medulla 

 oblongata; Lo, olfactory lobe; //, optic nerve; F, trigeminal; VII, VIII, 

 facial and auditory nerves; H, hypophosis cerebri; Th, optic thalamus; 

 Sr, sinus rhomboidalis. (After Claus.) 



The Nervous System. — The brain is relatively larger in 

 mammals than in other chordates. The cerebral hemispheres 



