274 NERVE COMPONENTS OF BONY FISHES. 



J. — T/ie Co7nmimis System, 



This system was composed primarily of the viscero- 

 sensory nerves, though as we actually find it in the head 

 much has been added upon this foundation; thus, it 

 includes not only nerves to the visceral or mucous sur- 

 faces, but to taste buds, to terminal buds of the outer 

 surface and to the teeth. It is represented in the X, IX 

 and VII nerves only, including all of the sensory IX, all 

 but the lateralis portion of the sensory VII and all but the 

 lateralis and general cutaneous portion of the sensory X. 

 Its ganglia are the geniculate ganglion of the VII nerve, 

 the whole of the IX ganglion and the branchio-visceral 

 ganglia of the vagus. All of these fibres terminate in the 

 lobus vagi — the vagus fibres directly, the others through 

 the mediation of the fasciculus communis. There is no 

 "lobus trigemini" or pre-vagal terminal nucleus, as in 

 many other fishes, this being correlated with the reduction 

 of the terminal bud system in Menidia. 



The viscero-sensory system of the trunk seems to have 

 been largly supplanted by the r, intestinalis of the vagus, 

 yet the spinal nerves retain a vestige at least of this 

 system. The centre in the spinal cord is uncertain, 

 though in the higher forms Clarke's column seems to be 

 related directly or indirectly to these fibres. In the fishes 

 the corresponding region, the "intermediate zone" prob- 

 ably contains a similar centre. This is suggested by the 

 way in which the descending tract from the lobus vagi 

 after passing the commissura infima Halleri runs back 

 into the intermediate zone. 



See Section 3, III; Section 5 ; Section 7; and Section 12. 



/j.. — TJie Motor Cojnponents. 

 The topographical relations of the motor nerves have 

 been fully worked out. These components were not the 



