NERVOUS SYSTEM. 



667 



wanting, There are thus only four metatarsals and digits. Each digit 

 has four phalanges. 



Nervous System. 



The brain has the usual five parts cerebral hemispheres, 

 optic thalami, optic lobes, cerebellum, and medulla oblongata, 

 but the cerebral hemispheres cover the next two parts, and 

 the cerebellum conceals the medulla. Of the brain mem- 

 branes, the dura mater lines the cranial cavity, projecting 

 longitudinally between the cerebral hemispheres, and trans- 

 versely between the latter and the cerebellum, while the 



./iff/ 



w... 



FIG. 236. Under surface of 

 Rabbit's brain. (After KRAUSE.) 



olf.l.) Olfactory lobes ; <?./., olfactory 

 tract \f.L, frontal lobe ; ch., optic chiasma ; 

 i.e., infundibulum ; c.m. corpus mammil- 

 lare ; 3, root of oculomotor ; 4, root of 

 pathetic ; 5, root of trigeminal ; 6, root of 

 abducens ; 7-8, roots of facial and auditory ; 

 /"7., flocculi of cerebellum ; //., i2th or 

 hypoglossal nerve ; 10, roots of vagus ; 9, 

 the line runs in front of the root of the 

 glossopharyngeal to the root of 6 \ p>v. t 

 pons Varolii ; /./., temporal lobe. 



vascular pia mater invests the brain closely. There are the 

 usual twelve pairs of cranial nerves. The spinal cord gives 

 off the usual spinal nerves, and there is a sympathetic system 

 as in most other Vertebrates. 



FIG. 235. Dorsal view of 

 Rabbit's brain, with most of 

 cerebellum cut away. (After 

 KRAUSE.) 



olf.l.) Olfactory lobes ; cJi., 

 cerebral hemispheres ; o.l., optic 

 lobes; 4.7'., fourth ventricle (ex- 

 posed); s.c., spinal cord; 10, root 

 of vagus; Ct>., lobe of cerebellum. 



