CRANIAL NERVES. 491 



nerve of higher Vertebrates becomes restricted to 

 the last three branches (5, 6, and 7). 

 A recurrent branch of the facial also runs external 

 to the auditory capsule to IX. , and is equivalent 

 to Jacobson's anastomosis in higher forms. 



VIII. The auditory, arising just behind VII., is the nerve 

 of the ear. 

 IX. The glossopharytigeal, the most typical of all, is the 

 nerve of the first functional gill-cleft. Its root 

 passes through the floor of the auditory capsule, 

 and bears a ganglion above the cleft. Its 

 branches, as named by Beard, are : — 



1. Post-branchial, to the muscles of the first branchial 



arch ; 



2. Prse-branchial, arches over the cleft and runs along 



its front wall ; 



3. Intestinal or visceral, to the pharynx ; 



4. Supra-branchial or dorsal, to a few sense organs on 



the mid-dorsal line of the head. 



X. The vagus, apparently made up of at least four 

 cranial nerves, has numerous roots, and divides 

 into six main ganglionated portions, which 

 supply the four posterior clefts and arches, the 

 posterior jelly-tubes, and the heart and stomach. 

 It thus consists of : — 



1. Ganglionated roots with nerves to the clefts and 



arches (2 to 5 inclusive), with post-branchial, 

 prEe-branchial, and pharyngeal branches as in 

 IX. 



2. A ganglionated root, arising in front of all the 



others, from which arises the lateral branch 

 innervating all the posterior sensory tubes. 



3. From the fourth branchial branch arises the gang- 



lionated intestinal which innervates the heart 

 and the stomach. 



The spinal cord lies in the cartilaginous neural archway 



SO., superior oblique muscle; E., eye; SR., superior rectus ; 

 ER., external rectus ; SO. VII., superficial ophthalmic branch 

 of VII. ; SO. V., superficial ophthalmic branch of V ; OP., oph- 

 thalmicus profundus; A. C, auditory capsule ; B.P1., brachial- 

 plexus ; R. F. t recurrent facial; C.T., chorda tympani ; F.P., 

 facial proper ; Hy., hyoidean ; Hyomn., hyomandibular ; E.M., 

 external mandibular ; M.M., mandibular muscle ; Sp., spiracle ; 

 P.sp., prespiracular ; PI., palatine; O.B., outer buccal; Mn., 

 mandibular; Mx., maxillary; I.B., inner buccal; L., lateral 

 branch of X. ; Py., pyloric branch ; C, cardiac branch. 



