CRANIAL NERVES OF SILURUS AND MORMYRUS 29 
its existence, since van Gehuchten*! and Tello® have shown its 
presence in the trout and van Valkenburg®* has demonstrated 
it in Lophius. : 
The addition of vagus fibers to the descending V tract—so 
obvious in Silurus—was not so conspicuous in my Mormyrus 
preparations, but I think that I have seen some of its fibers 
passing into the spinal V tract. 
While the visceral sensory VII was extremely large in Silurus, 
it is rather small in Mormyrus, being even the smallest of the 
communis nerves. It is not connected at its entrance with the 
V, as in Silurus, but only with its own motor root and the nervus 
lateralis anterior. Its fine fibers enter the brain medially of the 
coarse fibers of the VIII (figs. 16, 17). It runs over the spinal 
V and there splits up into two bundles. Here it is joined by the 
sensory IX (fig. 18). Together they run backward intimately 
connected and end in the dorsal lobe of the communis gray, in 
which no special facialis lobe can be distinguished. It may be 
even that some fibers of the VII terminate farther backward 
than the IX (see figure 18, where JX s. ends, but some VII 
fibers go still farther backwards). 
In opposition to Franz, I consequently believe that Mormyrus 
must not be regarded as a ‘taste fish’ with an extremely developed 
sensory VII, but rather as a fish in which the distribution of the 
sensory VII is very small in comparison with most other teleosts. 
The nerve described by Franz as nervus facialis is certainly the 
nervus lateralis posterior and this difference in interpretation 
appears to be fundamental, because it leads to an entirely differ- 
ent conception of the peculiar characters of the Mormyrus brain, 
since it appears that the enormous development of the valvula 
cerebelli in this animal does not depend on an increase of taste 
organs and their connections, as Herrick deduced from the 
misleading interpretations of Sanders and as was also defended 
31 yan Gehuchten, De l’origine du pathétique et de la racine superieure du tri- 
jumeau. Bul. Acad. des Sciences de Belgique, vol. 29, 1895, p. 487, fig. 3. 
32 Toc. cit., Trabajos, tomo. 7, 1909, p. 22. 
83. Van Valkenburg, Die mesencephalische Trigeminus Wurzel. Folia Neuro- 
biologica, Bd. 5, no. 4, 1911, p. 377. 
