Cog HILL, Cranial Nerves of Ambly stoma. 241 



around the border of the ear capsule, then dorsad along the 

 border of the m. extensor dorsi communis. Ventrally of this 

 muscle, however, the nerve divides. One of its divisions 

 {spt.i), passing more cephalad than the other and sometimes 

 penetrating under the insertion of the m. extensor dorsi com- 

 munis, innervates lateral line sense organs located well towards 

 the middle line of the head over the posterior moity of the ear 

 capsule. The other division {spt.2), passing either dorsally of 

 or through the first m. levator arcus branchii, innervates lateral 

 line organs at about the same transverse level as those inner- 

 vated by the first division but located farther laterad. 



5. — The Ramus Auricularis Vagi. 



The r. auricularis {aiir.) leaves the ganglion from the 

 latero-dorsal margin and at a transverse level between the first 

 branchial trunk of the vagus and the truncus glossopharyngeus. 

 In the adult, however, it arises farther caudad than the second 

 branchial trunk of the vagus. It is composed of lateralis fibers 

 from the first vagus root, and general cutaneous fibers from the 

 third vagus root. 



A short distance from the ganglion the r. auricularis forms 

 into two divisions, both of which are like the main nerve in 

 composition. The areas innervated by the two components of 

 the nerv^e approximately coincide. The anterior division of the 

 nerve {aur. i) extends dorsad and cephalad over the posterior 

 two-thirds of the ear capsule and laterad to the side of the 

 head. A general cutaneous nerve from this division {aur.i,a.) 

 extends caudad nearly to the base of the first external gill. The 

 posterior division of the nerve {atir.2) is distributed to the region 

 which lies immediately behind that of the first division. The 

 sense organs innervated by the lateral line components of both 

 divisions are somewhat irregularly arranged in groups through- 

 out the area of distribution of the nerve. 



6. — The Raitius Lateralis Superior Vagi. 

 The r. lateralis superior {l.s.) arises from the ganglion more 

 or less in union with the truncus visceralis. It sometimes forms 

 the dorsal part of the latter trunk for a short distance. It is 



