530 JULIA B, PLATT. 
liable to occur where, as in the present case, one sensory line 
meets another. 
I have traced the nerve twigs to each one of the terminal 
cluster of organs on the infra-orbital line, and find that four 
of the organs, which I have marked in the reconstruction, are 
supplied by nerve twigs composed in equal parts of fibres com- 
ing from the buccalis facialis, and from the ophthalmicus pro- 
fundus. These fibres unite in a common twig that goes 
directly to the heart of the sense-organ. 
Dohrn says (8, p. 274) that he has observed in the Selachii no 
mingling of the fibres of the ophthalmicus superficialis with 
those of the profundus, but considers such a union not impos- 
sible; while Strong (386, p. 179) speaks more positively of 
*‘the fact that the trigeminus proper does not participate in 
the innervation of the lateral line system,” as “‘ brought out by 
Allis (Amia), by Ewart (Lemargus and Raja), and by the 
writer (tadpole).”’ 
In this connection, the section given in Pl. 36, fig. 26, is 
significant. The figure shows one of the dorsal branches of 
the profundus, seen in the reconstruction (fig. 31), as it passes 
directly through the ramus ophthalmicus superficialis to the 
supra-orbital line, a sense-organ of which the section cuts 
tangentially. The following section shows the diameter of the 
ophthalmicus superficialis to be as great in the plane traversed 
by the profundus branch as it is in this section just posterior 
to that plane. In other words, a few fibres of the ophthal- 
micus superficialis lie outside of the branch from the ophthal- 
micus profundus, and, as the section shows, fibres from the 
superficialis join those from the profundus on their way to the 
sensory ectoderm. 
When one considers that the facialis invades a territory 
originally trigeminal, one is not surprised to find at every hand 
indications of the usurpation, showing that the separation of 
the specialised sensory tract, that finds its co-ordinating centre 
through the root of the facialis, is incomplete. Ido not, for 
this reason, include the trigeminus among the lateral line 
nerves, but should nevertheless hesitate to say that the “‘ tri- 
