122 



THE BRAIN OF FISHES 



they subserve, these Cranial Nerves fall into the following 



groups 



I. Nerves of 

 Special Sense. 



II. Nerves of 

 General Sensibility. 



III. Motor Nerves. 



( Olfactory. 



J Optic. 



1 Auditory. 



* Gustatory. 



( Large root of 5th. 



j Part of Glosso-pharyngeal. 



1 Yagus (the visceral nerve). 



( Motores oculi (3rd, 4th, and 6th 



I Small root of 5th. 

 ] Facial nerve. 



Spinal accessory. 

 (^ Sublingual or Hypoglossal. 



Taking the larger view held by Willis and others, as to 

 the limits of the Medulla Oblongata, and including under 

 this name all those parts of the Brain, 

 with the exception of the cerebellum, 

 posterior to the optic lobes, we find 

 the several pairs of true cranial nerves 

 (from 3rd to 9th inclusive) attached to it 

 on each side, and for the most part in 

 the order of their numeration (the 3rd 

 issuing from it close to the optic lobes, 

 and the 9th close to the junction of the 

 medulla with the spinal cord), with the 

 reservation that in Fishes the nerves of 

 the 8th pair are the last which pertain 

 to the medulla. 



The ' sensory ' nerves attached to the 

 Medulla, are, like those of the spinal 

 cord marked by ganglionic swellings 

 near or at the points of attachment of 

 such nerves (p. 44). 



Thus the roots of the Vagus or Pneumogastric in a large 



Fio. 57. Brain of the 

 Cod, under surface. 

 (Owen.) P, Cerebral lobes ; 

 o, optic lobes ; n, hypoa- 

 ria ; p, pituitary body ; 

 a, anterior pyramids ; 



2, optic nerves, crossing ; 



3, oculo-motor ; 5, trige- 

 uninus ; G, external ocu- 

 lar ; 7, auditory ; 8, vagus 

 and glosso-pharyngeal. 



