CUTANEOUS BRANCHES OF THE VAGUS. Ill 



importance, as mentioned above under the first spinal 

 nerve; for if these are somatic muscles, as Flirbringer 

 maintains, their innervation from the vagus can be ex- 

 plained only upon the assumption that either (i) one or 

 more neo-cranial segments have been secondarily incor- 

 porated into the vagus nerve, or (2) that a paleo-cranial 

 nerve may secondarily come into relation with a somatic 

 muscle belonging to a neo-cranial segment. Both of these 

 assumptions are denied by Flirbringer. It should be 

 mentioned that there is one further possibility, viz., that 

 these muscles may be innervated by somatic motor fibres 

 from the ventral horn which go out with the vagus roots. 

 Flirbringer does not admit this possibility either, and I 

 have not found such fibres in Menidia, but they are de- 

 scribed for Salmo (Haller, '96) and for Amia (Kings- 

 bury, '97). 



VIII. — Rami Cutanei Dorsales Vagi. 



These comprise those general cutaneous fibres which 

 are included with the vagus. Three very delicate nerves 

 arise from the jugular ganglion, which lies proximally and 

 just dorsally of the ganglion of the intestinal and fourth 

 branchial rami and only imperfectly separable from it. 

 These nerves pursue devious courses to the skin of the 

 opercular and supra-opercular regions. Two of these 

 arise from the caudal surface of the ganglion. One, di- 

 rected caudad {cut. X. j), is accompanied for a short 

 distance by the motor ramus for the trapezius muscle de- 

 scribed below. It then turns dorsad between the latter 

 muscle and the dorsal musculature, to reach the skin at 

 the caudal edge of the attachment of the operculum. 

 Both the outer and the inner surfaces of the operculum at 

 this point are supplied. 



Arising with the last, but abruptly turning cephalad, is 

 a second slender cutaneous twig distributing farther dor- 



