1 62 Journal of Comparative Neurology. 



The Cranial Nerves of the Bony Fishes. 



By C. JuDsoN Herrick. 



The cranial and first spinal nerves of Menidia have been 

 plotted by reconstruction from serial sections in order to ex- 

 hibit the relations of the nerve components both proximally 

 and distally. In most cases the several components have been 

 traced from their nuclei of origin or termination in the brain 

 through the ganglia to their peripheral termination. 



Throughout the gnathostome vertebrates we now common- 

 ly recognize four components in the typical spinal nerve — (i) 

 somatic motor, from the ventral horn cells ; (2) somatic sensory 

 (general cutaneous), terminating in the dorsal horn ; (3) vis- 

 ceral motor ; and visceral sensory. The central relations of 

 the last two components are still obscure. They are probably 

 both related to the "intermediate" or lateral horn zone, the 

 sensory fibers coming in by the dorsal root and the motor fibers 

 (in infra-mammalian groups, at least) going out by both dor- 

 sal and ventral roots. 



Now in the bony fish the cranial nerves exhibit these four 

 components and in addition a fifth, the acustico-lateral. The 

 somatic motor is represented by the eye-muscle nerves ; the 

 somatic sensory by the general cutaneous component of the V 

 and X nerves, terminating in the spinal V tract, which is the 

 continuation of the dorsal horn of the spinal cord ; the viscero- 

 motor by the motor fibers of the other cranial nerves, going 

 out near the sensory fibers by dorsal roots to the branchial 

 musculature. The viscero-sensory system, like the viscero-mo- 

 tor, has been hypertrophied and is represented by the com- 

 munis system of the X, IX and VII nerves, terminating, either 

 directly or through the mediation of the fasciculus communis 

 in the vagal lobe (chief sensory vagus nucleus of higher forms). 

 The communis system of the head, unlike the corresponding 

 visceral sensory system of the trunk, receives fibers from taste 

 buds and other sense-organs not belonging to the lateral line 



