No. I.] THE CRANIAL NERVES OF AMPHIBIA. 193 



root. One part of this double root must, of course, be motor 

 and pass into the R. hyomandibularis, the other part will, I 

 believe, be found to arise from the lobus vagi as in Acipenser. 

 I am inclined to believe that this will be found to be the con- 

 dition in all fishes, namely, the coexistence of both a root from 

 the lobus vagi and one from the lobus trigemini, and, further- 

 more, always a R. palatinus from the former at least, the 

 variable element in the palatine nerves being the part played 

 by the lobus trigemini root in their formation. 



Again, we have the discrepancy, which has been mentioned, 

 with regard to the R. ophthalmicus profundus, which, according 

 to some investigators, belongs to the Trigeminus proper and 

 according to others {e.g., Wright) is derived from the lobus 

 trigemini. It is possible that here again there is not a com- 

 plete separation or specialization of the fibres to end buds in 

 some forms (see below, however, on this point). 



This branch, the ophthalmicus profundus, has been discussed 

 by H. H. Wilder (71), who comes to the conclusion that the 

 ophthalmic branch of the Trigeminus in Amphibia represents 

 the united ophthalmicus profundus and ophthalmicus super- 

 ficialis trigemini. It seems to me that this is probably correct, 

 but the fusion has already taken place, in Salamandra maculata, 

 to which Wilder refers, inasmuch as the R. frontalis of Plessen 

 and Rabinovicz is, as we have seen, the R. ophthalmicus super- 

 ficialis facialis and not the R. ophthalmicus superficialis 

 trigemini. The latter, then, does not appear to be present as 

 an independent branch, and has already united with the 

 ophthalmicus profundus. The ganglion of the latter has 

 already fused, forming a part of the Gasserian ganglion, for the 

 " Nebenganglion " is a facial ganglion. 



Our view as to the fate of the ophthalmicus profundus, 

 however, will partly depend upon whether we find it to belong 

 to the Trigeminus proper or to the lobus trigemini root. If 

 the latter, it very possibly would have either undergone a 

 reduction or aborted, owing to loss of end buds in the nasal 

 region. 



The results of the majority of investigators, however, 

 certainly favor the view that the R. ophthalmicus profundus 



