216 EDWARD PHELIVS ALLIS, JUN. 



facialis, and was said to have its central origin " at a high 

 level in the brain, probably from the fasciculus comnuinis of 

 Osborne and Strong." The ramus ophthalmicus superficialis 

 trigemini of my description of Amia is certainly largely, and 

 perhaps entirely, composed of fibres derived from this com- 

 munis root. The ramus ophthalmicus superficialis facialis is 

 certainly largely, and probably entirely, composed of fibres 

 derived from the tubercnlum acusticum. The portio ophthal- 

 mici profundi is probably exclusively composed of spinal fifth 

 fibres. Compared with Acipenser the ramus ophthalmicus 

 superficialis of Amia thus contains a large communis compo- 

 nent, not found as such in Acipenser, while the nerve of 

 Acipenser contains a large lobus trigemini component not 

 found as such in Amia. The inference is evident that the 

 two components are homologous, and as the communis com- 

 ponent of the nerve of Amia is largely, and perhaps exclu- 

 sively, destined to the innervation of terminal buds, and as 

 there are neither nerve-sacs nor ampullae in Amia, these latter 

 organs of Acipenser and selachians must be the homologues 

 of the terminal buds of Amia. That the ampullae of selachians 

 are derived from the terminal buds of ganoids and teleosts 

 was Strong's impression, rather than opinion, for he says 

 (60, p. 202), in discussing selachians, that "it would seem 

 likely that those fibres in the lateral line nerves of the head 

 derived from the lobus trigeuiini are devoted to the innerva- 

 tion of the ampullae. If this were true, as further research is 

 necessary to show, the ampulla) would represent the end buds 

 of other fishes," 



The descriptions of other fishes do not throw much further 

 light upon this subject, but they are certainly in accord with, 

 rather than opposed to, my conclusions. The varying use and 

 misuse of descriptive terms, and certain probable errors in the 

 descriptions, make most of the comparisons very difficult and 

 of but little value. The probable homologies can, however, 

 be indicated. 



In Lota Goronowitsch (25) says that Trigeminus II arises 

 by two stems, a dorso-median and a ventro-lateral one. The 



