NERVOUS SYSTEM. 



539 



side will be seen the chiasma or interlaced crossing of 



the optic nerves, and a tongue-shaped mass (the tuber 



cinereum), to which the pituitary body is attached. 

 The optic lobes, 



a pair of oval 



bodies, between 



and below which 



is the iter. 

 The cerebellum, 



a very narrow 



transverse band. 

 The medulla ob- 

 longata, on the 



roof of which 



the pia mater 



forms a very vas- 

 cular " choroid 



plexus." 

 The cavities of the 



brain and the 



canal of the 



spinal cord are 



in the adult 



lined by ciliated 



epithelium. 

 The cranial nerves 

 are, as usual, on each 

 side the following : 



(i) Olfactory, from the 

 olfactory lobe to 

 the nose ; 



(2) Optic, crossing and 



interlacing with its 

 fellow ; 



(3) Oculomotor, to four 



muscles of the eye; 



(4) Pathetic, to the superior oblique eye muscle ; 



(5) Trigeminal, with ophthalmic, maxillary, and mandibular branches ; 



(6) Abducens, to the external rectus eye muscle ; 



(7) Facial, arising along with the auditory, with a ganglion uniting 



with the Gasserian ganglion of the trigeminal, with a palatine 

 branch to the roof of the mouth, and a hyoid branch to the 

 lower jaw ; 



(8) Auditory, to the ear ; 



Fig. 231. — Nervous system of frog. — After 

 Ecker. 



1-10, The crania! nerves ; oc, eyes ; crb., in frontot 

 optic chiasma; to. , optic tract; syjtr., sympa- 

 thetic system ; fnsp., spinal cord ; jr/., spinal nerves. 



