THE RAMUS OTICUS. 193 



from the Gasserian ganglion, the latter from the dorsal lat- 

 eral line nerve just at the point where it divides to form the 

 nn, buccalis and ophthalmicus superficialis VII, The r. 

 oticus now runs cephalad and dorsad between the cranium 

 and the m. levator arcus palatini and here divides, one 

 twig continuing cephalad in the original position, the other 

 directly dorsad through a foramen in the base of the post- 

 orbital process of the frontal bone to turn caudad along 

 the roof of the cranium under the main lateral line canal 

 of the head. It contains 15 very coarse fibres and about 20 

 fine ones. Both components reach the lateral line canal 

 through a foramen in the squamosal bone, the coarse fibres 

 being external. These latter supply the single canal organ 

 of the main lateral line between the opercular and the 

 infra-orbital lines. The fine fibres could not be traced to 

 their termini. They probably break up and lose their 

 sheaths in the loose connective tissue surrounding the 

 membraneous canal and possibly reach the overlying 

 skin. 



The twig of the r. oticus which is directed forward also 

 contains both coarse and fine fibres. It turns laterally 

 around the cephalic end of the m. levator arcus palatini 

 and a portion of the coarse fibres enters a foramen in the 

 most dorsal post-orbital bone to supply the single organ 

 of the post-orbital section of the infra-orbital canal. The 

 remaining fibres turn ventrad and anastomose with a fine- 

 fibred nerve from the supra-orbital trunk. Fine fibres 

 from both of these sources supply the skin around the 

 post-orbital section of the infra-orbital canal. The coarse 

 fibres run down under the skin close behind the eye and 

 supply the 13th and 14th infra-orbital lateral line organs, 

 these being the last of the series of naked infra-orbital 

 organs. In my preliminary paper ('97) it was erroneously 



