CEEEBBAL NEEVES OF VEBTEBEATA. 



519 



of branchial arches (Fig. 290). The first branchial branch (br 7 ) 

 passes to the second branchial arch, and also gives off a fine twig" to 

 the first arch. In this point the branchial branches of the vagus 



i»\7 



Fig. 290. Cephalic nerves of Hexanchus griseus. On the right is figured as 

 much of the course of all the cephalic nerves as can be seen from above. The cranial 

 cavity and spinal canal are both laid open, so that the brain and spinal chord are 

 exposed. The right eye and its muscles is removed. On the left, the roof, only, of 

 the oi-bit is removed, so that the bulb and its muscles are exposed to view. The 

 region of the labyrinth, and of the occipital portion of the cranium, has been removed 

 as far as the levels of the nerve-trunks, which pass out through them. A Anterior 

 fontanelle (cranial lacuna). N Nasal capsule. Bo Bulb us olfactorius. Tr' First branch 

 of the trigeminal. a Its terminal twig in the ethmoidal region. Tr" Second 

 branch. Tr'" Third branch, tr Trochlears. Fa Facialis. Gp Glossopharyngeus. 

 Vg Vagus. L Ramus lateralis. J Ramus intestinalis. os Muse, obliq. oc. sup. 

 ri M. rectus internus. re M. rectus externus. rs M. rectus superior. S Spiracular 

 cleft. Pq Palato-quadrate. Hm Hyomandibular. r Branchial rays. 1—6 Branchial 



arches. hr r — hr v Branchice. 



resemble the glossopharyngeal and the facial, which likewise send 

 off fine twigs to the arches next in front of them. A pharyngeal 

 branch is given off at the point where this branchial branch divides. 

 The vagus trunk is continued on, as an intestinal branch (g), to 



