92 JoURNAL OF COMPARATIVE NEUROLOGY. 
given the name it now bears by Oszorn (88) in recognition of 
the common relationship of several cranial nerves to it. Vari-- 
ous authors had noticed the fasciculus communis previous to 
this time, but they had failed to grasp its significance. STIEDA 
(73a, p. 439) had noted the presence of such a bundle in the 
spinal cord of the selachian; while Ronon (’77, p. 46) de- 
scribed it from the selachian brain under the name /ascéculus 
longitudinals laterals. The latter writer conjectured that it 
might pertain to the tegmental system. 
In Mustelus, the fasciculus communis is a very sharply 
defined tract extending posteriorly from the VII nerve into the 
spinal cord, where it lies close beside the gray matter dorso- 
lateral to the canalis centralis. Its position in the oblongata is 
shown in Fig. 2, f. c. During a part of its course, the viscero- 
motor nucleus is traversed by it. Some of the communis fibres, 
instead of pursuing a course to the lobus vagi for termination 
there, turn downward into the fasciculus communis. Thence 
they are carried posteriorly into the spinal cord for their ulti- 
mate distribution. 
From the account given by Srrone (’95) of the fasciculus 
communis in amphibians; and by HErRIcK (99) for the bony 
fish, I conclude that this tract is developed in Mustelus to a 
conspicuously less degree. The significance of this smaller size 
for the brain of the selachian is not clear. The communis 
fibres are essentially viscero-sensory, but there have been an- 
nexed to the system certain external sense-organs, such as 
taste-buds and end-buds. There are no observations indicating 
marked differences between the visceral connections of this 
spstem in Mustelus as compared with teleosts and amphibians. 
In fact, the archaic value and deep-seated physiological impor- 
tance of such connections in all vertebrates would lead us to 
infer a considerable similarity in related groups. We thus ap- 
pear to be thrown upon the more recent additions to the system 
-for the explanation. It seems to me that a comparative inves- 
tigation of end-buds and taste-buds will contribute much toward 
the solution of questions pertaining to their central tracts. 
Se ee 
