398 Journal of Comparative Neurology. 



the fact that the reduction in size of some of the organs 

 of the lateral line has involved the reduction also of the 

 calibre of the nerve fibres which supply these organs, so 

 that the normal distinction between lateralis and com- 

 munis fibres is in a measure obscured. Nevertheless, I 

 think that the conclusions as expressed on the plots are 

 correct. 



I am convinced that in Menidia the r. lateralis vagi does 

 not innervate any organs other than those of the lateral 

 line. The participation in the general innervation of the 

 skin or muscles can be excluded. The fibres from this 

 nerve which anastomose with the r. lateralis accessorius 

 are much finer than any lateralis fibres. In a few cases 

 fibres from these anastomosing nerves supply naked 

 cutaneous sense organs. These fibres, too, are finer than 

 the lateralis fibres and I regard them and the anastomosing 

 fibres as both belonging to the communis system. They 

 may be derived from the lobus vagi by either one or both 

 of two paths: (i) The fine fibres already mentioned as 

 emerging from the brain in the lateralis root enter that 

 root on its caudal side and may be derived from the lobus 

 vagi, though they could not be traced back into it. 

 (2) The anastomosing fibres from the root of the glosso- 

 pharyngeus to the lateralis root are almost certainly 

 communis fibres and I look upon this tract as the probable 

 source of all of the fibres under consideration. ' These 

 fibres, as they separate from the IX root, are rather larger 

 than the other fibres of that root but not nearly so large 

 as the proper lateralis fibres, i. e., they are about the same 

 size as the fibres of the branches of the r. lateralis which I 

 have designated as belonging to the communis system on 

 the plots. 



The dorsal cutaneous rami of the vasfus have been 



