244 NERVE COMPONENTS OF BONY FISHES. 



supplies the three organs of the main line immediately 

 caudad of the commissure. This is a condition not known 

 for any other vertebrate and indeed Ewart himself had 

 predicted ('93, p. 72) that if the IX nerve should prove to 

 supply any portion of the lateral line of the head it 

 would be the pre-commissural, not the post-commissural 

 portion. 



The fibres which I have described running from the 

 IX root to the lateralis root have an exact counterpart on 

 a larger scale in Amia (Allis, '97, p. 625). They are 

 described as coming from the ventral, i. c.^ communis, 

 portion of the IX root, and not from the dorsal, or lateralis 

 portion. What the fate of these fibres is peripherally in 

 Amia, has not been determined. It is natural to assume 

 that they supply either terminal buds of the trunk or 

 accessory lateral line structures. 



Allis ('97) assumes, I think correctly, that the terminal 

 buds scattered over the bodies of many fishes, {e. g. gad- 

 oids) are innervated by the r. lateralis accessorius, which 

 is distributed to those regions. There are, however, in 

 some fishes extensive regions of the body not reached by 

 this nerve which are known from the researches of Leydig 

 and others to be abundantly supplied with terminal buds, 

 which are said to be innervated by the r. lateralis vagi. 

 Now, if this passage of communis fibres into the r. later- 

 alis, as we find it in Menidia, is of general occurrence, it 

 clears up a serious difficulty in the interpretation of these 

 terminal buds. We have seen that such is the case in 

 Amia and from Allis' account ('89) it would appear that 

 the anastomosis is there much larger than in Menidia. 



I predict that in cyprinoids, where the lobus vagi is so 

 large, and the body is known to be covered with terminal 

 buds (Leydig, '94) that these will be found to be supplied 



