86 JOURNAL OF COMPARATIVE NEUROLOGY. 
diate zone of gray matter in the cord. The viscero-sensory 
system in its original condition is, however, of far less impor- 
tance than its cranial representative. The communis system 
not only innervates visceral organs, but it has come into rela- 
tions with taste-buds and peripheral end-buds, as well. It there- 
fore is a system having a very considerable magnitude. 
e. The Acustico-Lateral System is concerned exclusively 
with the innervation of the internal ear and the organs of the 
lateral line. Its fibres are components of the VII, VIII, and 
X nerves. They penetrate the tuberculum acusticum for im- 
mediate termination there or for a course farther forward into the 
cerebellum. The significance of the latter termination will be 
discussed later. The components of this system in the VII 
and X are to be readily distinguished from other fibres associ- 
ated with them by virtue of their great diameter. 
The acustico-lateral system is not represented in the spinal 
nerves, as the four preceding cranial systems are. The evolu- 
tion of this system is bound up with that of the peculiar series 
of sense-organs which it supplies. Until the evidence is more 
nearly complete as to the embryology and affinities of the lat- 
eral line and its nerves as a whole, we really are not warranted 
in making any positive assertion as to its phylogeny. Some 
evidence as to the possible origin of its centre will be given 
in Subsection 7. 
3.  Neurones of the Ventral Cornu. 
Upon reaching the level of the oblongata, the ventral 
cornua of the cord become broken up as distinct collections of 
nervous matter. Somatic motor neurones from this source are 
grouped into the nucleus for the VI nerve, but elsewhere there 
are only isolated individuals lying between the fibres of the 
formatio reticularis. In an earlier paper touching this subject 
(‘97b), I left the interpretation of these scattered neurones 
undecided. It is now certain that they correspond to the com- 
missural cells and the tract-cells ( Vorderstrangzellen), respectively, 
which von LENHOSSEK (’94) has mre! from the spinal cord 
of the selachian. 
