516 WALTER EDWARD COLLINGE. 
olfactory capsule they run almost parallel to each other. Ac- 
cording to van Wijhe it divides into two branches, a dorsal 
one which passes over the olfactory capsule, and another to the 
fore part of the orbit. 
3. The ramus maxillaris is a large nerve passing beneath the 
orbit and dorsal to the ramus palatinus of the facial. It passes 
along the whole length of the rostrum. 
4, The ramus mandibularis passes ventral to the hyomandi- 
bular bone across the cheek in an oblique direction. Anterior 
to the symplectic cartilage it divides into two branches, the 
anterior one sending branches to the muscles and primitive 
pores in the region of the maxilla, whilst the posterior branch 
innervates the muscles in the mandibular region. 
5. The ramus oticus is the most posterior branch of the 
trigeminal group. It is a dorsal branch which passes back- 
wards. Van Wijhe describes it as passing dorsally through a 
canal, and terminating just in front of the foramina of the 
vagus. In front of the vagus, however, it turns forwards again 
and innervates the cluster pores between the occipital region 
and the spiracle (Pl. 40, figs. 11 and 12, 1. of.). 
The Facial group consists of the following five branches— 
1. The Ramus palatinus? 
2. The Ramus buccalis. 
3. The Ramus mandibularis. 
4. The Ramus hyoideus. 
5. The Ramus opercularis. 
1. The ramus palatinus?—Presumably this is the ramus 
palatinus of van Wijhe. It is the most anterior branch of the 
facial, and passes beneath the orbit and olfactory capsule, 
having an almost parallel course to the ramus buccalis (Pl. 
AO wig, dd; 7.5p-), 
2. The ramus buccalis is the chief branch innervating the 
canals and sensory organs. In Polyodon it is developed to an 
unusual extent. Its course lies ventral to the orbit, imme- 
diately in front of which it divides into two branches, these 
again dividing more anteriorly. These are termed respectively 
a, b, c, d, and e. | 
