606 



2) That the large sensory root of the Facial, dorsal to the Auditory 

 (dorsal VII.) together with the anterior root of the Glosso- 

 pharyngeal form a distinct group by themselves, differentiated from 

 the others by their internal origin and by the character of their fibres 

 and belonging distinctly to the organs of the lateral canals. 

 It is possible that the Auditory may have some relation to this system 

 of nerves. 



3) That the Amphibia are transition types since in them we can 

 trace the disappearance of the above group of nerves, so characteristic 

 of the Fishes. The Urodela approach the piscine condition with their 

 large dorsal sensory VII., the Aiiura approach the higher vertebrates 

 with the dorsal sensory VII. wanting and the ventral motor VII. conse- 

 quently more prominent. The remaining portion of the Facial, that 

 arising from the Fasciculus communis, is possibly the homologue 

 of the Portio intermedia. 



4) That, as observed by O shorn, we have in the medulla at least 

 two series of motor nuclei: (A) one series those of the III., IV., VI. and 

 XII. nerves, (B) and the other series, those of the motor V., ventral 

 motor VII. and of a number of ventral rootlets of the IX. -f- X., which 

 latter rootlets may, I believe, be regarded as homologous with the 

 medullary portion of the XI. 



5) It is the second series which, in position and in the size of the 

 cells, seems to correspond most closely with the large cells in the 

 anterior horn of the spinal cord of the Frog. 



6) That in the medulla we have a remarkable concentration of 

 certain tracts. This has been mentioned by Gaskell and should be 

 extended to include the Fasciculus communis and those tracts 

 connected with the organs of the lateral line. 



7) That the Fasciculus communis, of Osborn, is an afferent 

 splanchnic tract supplying parts of the epithelium of the mouth and 

 alimentary canal. 



Princeton, Aug. 28., 1890. 



Bibliography. 



1) Fr. Ahlborn, Über den Ursprung und Austritt der Hirnnerven von 

 Tetromyzon. Zeitschr. f. wiss. Zool. 39. Bd. 



2) E. P. Allis jun., The Anatomy and Development of the Lateral Line 

 System in Amia calva. Journ. of Morph. Vol. IL No. .3. April 1889. 



3) Alexander Ecker, The Anatomy of the Frog. English trans, by Geo. 

 Haslam, 1889. 



4) J. C. E wart, On the Cranial Nerves of Elasmobranch Fishes. Preliminary 

 communication. Proc. lloyal Society, Vol. XLV. March 1889. 



5) J. G. Fischer, Anatomische Abhandlungen über die Perennibranchiaten 

 und Derotremen. 1. Hft. 1864. 



