24 H. BERKELBACH VAN DER SPRENKEL 
posticum, so that the secondary lateralis tract has a course and 
ending similar to the secondary ascending octavus bundle in 
mammals. 
Descending fibers from the lobus nervi lateralis anterioris 
can also be traced. They are, however, not so easily recogniz- 
able as the ascending system. 
It is interesting, in view of the probable relations of their 
functions,!® that the endings’ of the vestibular nerve show so 
many resemblances with those of the lateralis nerves. 
The nervus vestibularis is not very strongly developed in Silurus, 
probably in correlation with the sluggish life of the animal, and 
it enters the brain by two roots (fig. 11; cf. Juge, loc. cit., p. 98). 
The most frontal root (fig. 6) enters the brain rather far ven- 
trally in the bulb, and then divides into ascending and descend- 
ing fibers. We find fibers which run between the spinal V and 
the sensory VII; ascending in this area they turn mesad. They 
are of the same character as the lateralis fibers of this region and 
many of them cross the raphé (fig. 11, a), the rest of them running 
forward and ending in the Idbus lateralis anterior (fig.6, VII a.t.). 
Wallenberg?® also has demonstrated with Marchi’s degener- 
ation that the vestibular nerve in teleosts possesses crossing 
fibers. Exactly where these fibers end I have not been able to 
see. Some of the coarser lateralis fibers accompany this system. 
Other descending fibers, likewise running between the spinal 
V and the sensory VII roots, descend in a dorso-medial direction 
and end in the most ventral part of the gray substance of the lobus 
lineae lateralis anterioris [fig. 11 (9) and fig. 6, VIJJ a.t.]. 
Several vestibular fibers of the first root also run directly be- 
neath the crista, forming descending systems [fig. 11 (10)]. An 
19 G. H. Parker, The function of the lateral line organs in fishes. Bul. of the 
Bureau of Fisheries for 1904, Washington, 1905, vol. 24, p. 185.’ The lateral line 
organs are stimulated by water vibrations of low frequency, 6 per second. ‘The 
skin, the lateral organs and the ear (meaning the labyrinth in toto—B.v.d.8.) 
form a natural group of sense organs. The organ of touch may be said to be the 
first generation, from which the lateral line system has been derived, and this in 
turn has given rise to the ear. 
20 Beitriige zur Kenntnisse des Gehirnes der Teleostier und Selachier. Anat. 
Anz., Bd. 31, 1907, -p. 374. 
