MTJSTELUS LMV\S. 225 



ophthalmicus snperficialis trigemini of Amia are represented 

 in Acipenser and selachians by those fibres of the ramus 

 ophthalmicus snperficialis of the latter fishes that have their 

 origin in the lobus trigemini, it may be noted that Gorono- 

 witsch says (25, p. 8) that a few fibres of the dorsal or lobus 

 trigemini root of Trigeminus II of Acipenser can be traced 

 back into the lobi vagales. As no other communis fibres are 

 found, as such, in the ophthalmic nerves of the fish, are these 

 few fibres the remnant of an aborting nerve, or are they a 

 few fibres, still unchanged, of a nerve that is undergoing 

 modification ? My impression is decidedly in favoxir of the 

 latter one of these two suppositions. That connnunis fibres, 

 as such, once existed in these ophthalmic nerves, and that 

 some of them have actually undergone modification, must be 

 admitted if it be accepted that the sensory organs of the 

 lateral canals of all fishes pass tl trough a stage represented 

 by the terminal bud (64, p. 298). 



It should here be noted that Herrick concludes (32, p. 169) 

 that his own work, and Johnston^s also, favours the belief that 

 the acustico-lateral has been differentiated from the general 

 cutaneous system, and hence not from the communis system. 



The ramus ophthalmicus profundus now remains to be 

 considered. This nerve is almost invariably said to be a 

 purely sensoiy one, excepting- only in the Myxinoids, Avliere 

 it is said to have motor branches. Haller's assertion that the 

 profundus of tScyllium is entirely motor (28, p. 438) has 

 already been referred to ; but apart from the fact that this 

 statement is probably an error, his profundus nerve is quite 

 unquestionably simply the portio minor of the ophthalmicus 

 superficialis, aiul has been already discussed. 



In Chinuera, Cole says (11, p. 645) that one of the branches 

 of the ophthalmicus profundus is possibly motor, and that its 

 origin and distribution make it exceedingly probable that it 

 corresponds to the motor division of the profundus found in 

 the Cyclostomata. The nerve thus referred to in Chimasra 

 lies dorsal to the opticus. The motor nerve with which it is 

 compared lies ventral to the opticus in both Myxine and 



