236 CLAPP. [Vol. XV. 



by branches of the IX, while the two others are probably 

 homologous with the organs forming the cross-commissure of 

 Amia. (Compare Figs. 21 and 23.) 



Another branch {v^), arising from the anterior root of the 

 vagus just outside the cranium, and taking a course upward and 

 backward, innervates the four organs of the dorsal line (Fig. 

 22, dl.). 



Fig. 13 shows an intracranial commissure between the VII 

 and X. The branch from X which anastomoses with the R. 

 recurrens facialis (Fig. 13) arises from the posterior root of the 

 vagus. It is also evident that the fibres of the R. recurrens 

 facialis emerge with the ventral root fibres of the VII. It is 

 probable that the components of this nerve have a different 

 central termination in the medulla from the dorsal branches 

 of the VII and the anterior root of the X. The innerva- 

 tion of the body lines in Batrachus presents a somewhat 

 puzzling problem, which can only be solved by a careful study 

 of the terminations or origin of the fibres in the medulla. The 

 apparent course of the nerves is often deceptive, as fibres hav- 

 ing different eentral connections are enclosed in the same slieath 

 outside of the medulla, or, the central connections being the 

 same, the fibres follow different pathways to their destination. 

 A case in point is that of the glosso-pharyngeal, which seems 

 to take no part in the innervation of sense organs in Batrachus, 

 although in Amia one canal organ and a line of pit organs are 

 supplied by that nerve.^ It is probable that the fibres inner- 

 vating the organs are enclosed sometimes with the IX and 

 sometimes with the X nerve. 



The attempt to homologize the body lines of Batrachus 

 seems useless until a better knowledge of the components of 

 the so-called R. recurrens facialis is obtained. It seems prob- 

 able that this nerve is identical with the R. dorsalis recurrens 

 trigemini (Stannius), which is said to innervate a line of end 

 buds at the base of the dorsal fin in Siluroids, but the dorsal 

 body line of organs in Batrachus would hardly seem homologous 

 with this line of end buds. 



1 In a recent paper {Journal of Morphology, vol. xii, p. 747) AUis has shown 

 that the " so-called dorsal root " of the IX is composed of fibres from the lateral 

 line root of X. 



