THE SUPRA-ORBITAL TRUNK. 20I 



large branch enters the dentary canal of that bone and 

 turns back in it, probably supplying the teeth. These are, 

 doubtless, communis fibres. 



The three sense organs, g; /i, z, above the anterior 

 nasal aperture which are supplied by the superficial oph- 

 thalmic nerve resemble those of the same neighborhood 

 which are supplied by the infra-orbital trunk and they 

 are, doubtless, of the same nature. The same ambiguity 

 holds here as there; I incline to the belief that they 

 correspond to pit-organs. 



Communis fibres can be clearly traced into the supra- 

 orbital trunk. What their distribution may be is not so 

 clear. Apparently they are of a simple visceral nature 

 for the internal organs of the head. Terminal buds are 

 known to be supplied by communis fibres of the r. oph- 

 thalmicus superficialis in some fishes {e. g.^ Amia, 

 Allis, '97). The naked sense organs on the barblets of 

 siluroids are unquestionably supplied by communis fibres. 

 My own preparations of Amiurus substantiate this. The 

 nasal barblet is stated by Wright ('84, p. 367) to be inner- 

 vated by the r. ophthalmicus profundus in Amiurus; this 

 nerve is, however, the ophthalmicus superficialis, as Allis 

 has suggested ('97, p. 539). 



Stannius clearly recognized the lateralis and general 

 cutaneous components of this supra-orbital trunk and the 

 origin and distribution of each. The lateralis component 

 he identified with the r. frontalis, the general cutaneous 

 with the r. nasalis of higher vertebrates (p. 35), the former 

 of course being an impossible homology. 



Goronowitsch describes the nerves entering this trunk in 

 Lota vulgaris but erroneously names the ventral, or tri- 

 geminal, nerve ('96, p. 27) the r. ophthalmicus profundus. 

 From his brief statement of the peripheral distribution 

 this is clearly impossible. He describes and figures in 

 this nerve (z. c, the r. ophthalmicus superficialis V) a 

 large bundle of communis fibres from the communis root 

 of the facial (his dorsal root of the VII nerve). 



