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“hypoglossal” nerve, or first spinal, but we do not con- 
sider this to be a cranial nerve in fishes. 
3. Communis (Viscero Afferent?) System. — Partly 
synonymous with the fasciculus communis system of 
Osborn and Strong. A striking feature about this sensory 
system is that it may innervate both ecto- and endo-dermal 
surfaces, and it may therefore be disputed whether it is a 
visceral nerve that has invaded the skin, a somatic nerve 
that has invaded the visceral surfaces, or a complex of 
more than one component. The latter seems perhaps the 
most probable. The fibres of the communis system are 
fine and lightly myelinated, and are _ distributed 
peripherally as follows :—(qa) to the special sense organs in 
the outer skin called “terminal buds,” 7.e., to all the 
definite sense organs of the skin not belonging to the 
lateral line system. This part of the component has been 
reduced in the plaice; (+) to taste buds in the mouth; 
(ce) to the general mucous surfaces without the interven- 
tion of sense organs at all. The ganglia and cranial 
nerves into which the system enters are: (a) the genicu- 
late ganglion (vii.), glossopharyngeal ganglion (ix.), and 
the intestinal and four branchial ganglia of the vagus (x.). 
Any communis fibres in the trigeminus arise from the 
communis facialis. The central origin of the component 
is the Lobus vagi, and the enormous vagal lobes of 
Carpiodes are simply due to the hypertrophy of the com- 
munis vagi component in this fish (Herrick). Further the 
so-called Lobus trigemini of some fishes (Amzurus) is due 
to the hypertrophy of the communis facialis, and hence it 
should be called Lobus facialis. 
4. Viscero Efferent System.—This comprises the 
motor roots of the vth, viith, ixth and xth cranial nerves. 
Each of the first two has its own motor nucleus in the 
brain, but the two latter arise from collections of cells 
L 
