116 JOHN BEARD. 
It is hardly necessary to repeat that Gegenbaur’s view of the 
composition of the vagus out of a number of typical posterior 
roots is quite true. We have seen that it really contains 
rudiments of at least five such elements in Torpedo. 
It follows from this that the vagus agrees with the schema 
given in the preceding pages. It is equivalent to, and shows 
the development of, at least four such schematic nerves. True 
there is only one supra-branchial branch,! the lateral nerve, for 
all the elements of the vagus except the first. But this is 
probably secondary, and due to the fusion of the posterior 
elements of the vagus, and, as stated before, vg. 2, 3, and 4, 
all give fibres to the lateral line. 
It is worth mentioning here, because these researches con- 
firm one of Balfour’s views, that the “lateral line” was 
originally, as he believed, restricted to the anterior part of the 
body. The whole development of all these branchial sense 
organs shows the truth of this. But it is, at the same time, a 
very curious fact that these sense organs along the trunk of 
Teleostei are segmental (fig. 44, d7. 0.). This is well known, 
and is figured in the above figure, which is part of a horizontal 
section of a salmon hatched about six weeks. 
At one time I believed with Eisig and others that great 
morphological importance could be attached to this fact, but I 
feel now compelled to adopt Balfour’s view, and in discussing 
the morphology of these sense organs I shall strongly urge 
that in face of the facts of development here recorded, the 
morphological connection between these branchial sense organs 
of Vertebrates and the “ Seitenorgane” of Capitellide, first 
suggested by Hisig,? becomes of a very doubtful nature. And 
here again I may be permitted to remind the reader that 
Balfour’ long ago rejected the existence of any homology 
between these two sets of organs. 
1 In Torpedo and many other forms. In other cases the “ lateral line ” is 
more complicated ; especially is this the case in Amphibia, vide Malbrane, 
op. cit. 
- Kisig, “Die Seitenorgane der Capitelliden,” ‘ Mittheil. a. d. Zool. Stat. 
zu Neapel,’ vol. i. 142. 
3 Balfour, ‘Comp. Embryol.,’ vol. ii, p. 142. 
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