OBSERVATIONS ON THE CRANIAL NERVES OF SCYLLIUM. 497 
brates ; they attain their maximum development in the Hlasmo- 
branchs, probably on account of the great development and 
importance of the organs they supply—the mucous canals. In 
Mammalia the ophthalmic branch of the fifth is represented by 
the frontal and lachrymal nerves, while the seventh nerve has 
no ophthalmic branch. 
It would hardly be profitable to discuss the various descrip- 
tions of these nerves by different writers; we will merely point 
out here that Schwalbe! clearly distinguishes the three ophthal- 
mic nerves. He calls, as we have done, the ophthalmic branches 
of the seventh and fifth nerves together the ramus ophthalmicus 
superficialis, distinguishing the component parts as portio major 
(vita) and portio minor (v a) respectively. He also employs the 
term ramus ophthalmicus profundus in the same sense as we have 
done. Balfour, who was the first to clearly recognise the double 
nature of the ophthalmicus superficialis, is in error in calling the 
lower portion of it (va) the ophthalmicus profundus. 
Concerning the other branches of the nerves in question, there 
can be little doubt that the hyoidean branch (vii ¢) of the seventh 
and the mandibular branch (ve) of the fifth are homologous 
nerves, supplying respectively the anterior walls of the hyoidean 
and mandibular arches; and there appear to be good reasons for 
viewing the nerve (111 ¢) as the corresponding branch of the 
third.’ All the three nerves in question are either mainly or 
exclusively motor in function. 
The seventh, like the hinder cranial nerves, forks over a 
visceral cleft—the spiracle. As shown in figs. 11 and 12, there 
are two branches of the seventh which run down in front of 
the spiracular cleft, viz. the buccal (vir d) and the mandibular 
(vit 4), which latter divides almost at once into the palatine and 
spiracular nerves. Of these two a history of their development 
and a comparison of the branches of the seventh with those of 
the glossopharyngeal (1x, fig. 12), leave no possible room for 
doubt that the mandibular branch (vir 4) is the homologue of 
the anterior branch (1x 4) of the glossopharyngeal. This latter 
nerve (Ix 4, fig. 12) extends very far forwards in the hyoidean 
arch, being in this respect very closely imitated by the palatine 
nerve (VII, pa), so that we are disposed to regard the whole of 
the mandibular division (vit 4) of the seventh, 2. ¢. both palatine 
and spiracular nerves, as together equivalent to the anterior or 
hyoidean branch (1x 4) of the glossopharyngeal. 
' “Das Ganglion Oculomotorius,” ‘Jenaische Zeitschrift,’ Bd. xiii, 
pp. 11 seg. 
? Marshall, loc. cit., p. 88. 
