106 JOHN BEARD. 
existence of a hyomandibular segment in front of the hyoid 
and behind the mouth, but has not adduced the cranial nerves 
in support of his view. I would here venture to suggest that 
an additional ground for his view is to be seen in the exist- 
ence of two supra-branchial nerves in the facial. It would 
indeed be remarkable if Van Wijhe were correct in regarding 
these two nerves as merely branches of one nerve, for in no 
other single and simple cranial nerve do we meet with more 
than one supra-branchial nerve. To my mind the best expla- 
nation of the presence of these two branches is that the facial 
is composed of the fusion of two cranial segmental nerves, 
and this apart from its fusion with the auditory. The 
reader may compare Dohrn’s views on the nature of the hyo- 
mandibular with this explanation. Except for this the facial 
seems to be a fairly typical cranial nerve, and agrees well with 
the general schema. It should be noticed that the supra- 
branchial branches grow forwards, for this point will be re- 
ferred to in discussing the vagus. Though I agree fully with 
Van Wijhe’s! view that there are two segments in the hyoid 
arch, and this apart from the hyomandibular portion, I cannot 
treat the auditory nerve here. The special modifications it has 
undergone will be best considered after some of the other 
nerves have been discussed. In their earliest appearance I - 
believe the auditory and facial nerves are not fused, and even 
in the later stages (figs. 21, 42), as already noticed by Marshall 
in the chick, the ganglia of the two nerves are partially sepa- 
rated, and the line of division is easily recognisable. For the 
later stages of the facial the reader is referred to Marshall’s 
works and to the paper by Marshall and Spencer. 
NERVE OF THE SEVENTH SEGMENT—GLOSSOPHARYNGEAL. 
This nerve arises from the neural ridge (Balfour) immediately 
behind the auditory organ. It grows down to the lateral wall 
of the body to just above the point of origin of the first true 
branchial cleft. Its fusion with the skin is represented in fig. 
1 Op. cit., pp. 9 and 28. 
