1906.] NERVES OF CHLAMYDOSELACHUS ANGUINEUS. 973 



t. hyomandibulai'is. On the inner and caudad side the tri- 

 gemino -facial ganglion sends three fine nerve-strands to the 

 hyomandibnlar ganglion. There is to the naked eye no indication 

 of a separate ganglion for the superficialis o23hthalmicus VII., 

 vphich is given off at right angles from the anterior end of the 

 composite gangHon. Hoots A and B, which are nndoubtedly 

 lateralis, give rise to the bixccalis and ophthalmic-facialis rami, 

 whereas the corresponding roots of Chimcera (4) give rise not only 

 to these lateralis nerves but also to the external mandibularis. 

 It will be interesting to know whether in Chlainydoselachus, as 

 well as in Chimcera^ each of these lateralis rami is made up of 

 fibres from both roots. 



(«) The superficialis ophthalmicus VII. passes forward and 

 slightly upward. The nerve lies at first in a groove in the 

 cartilage, hnt soon this groove becomes a complete canal. At 

 frequent intervals from the very origin, the nerve gives off branches 

 to the supra-orbital lateral line canal. When, somewhat beyond 

 the anterior wall of the orbit, the nerve n^akes a bend outwards, 

 it sends off* a great number of branches to supply the two groups 

 of supra- orbital ampuUte of Lorenzini and the neuromasts in the 

 anterior loop of the supra-orbital canal. The main nerve here 

 bends downwards to supjily the last 15 neuromasts of the supra- 

 oi'bital canal, 



ib) The ramus huccalis originates from the inner posterior 

 angle of the buccal ganglion. It passes obliquely downward and 

 forward across the orbit and the side of the head, towards the 

 mouth in the region of the external nares. Beginning at its 

 origin, the nerve gives off many small branches, which pass 

 backward and downward to supply the neuromasts of the infra- 

 orbital canal. There are about eleven principal branches, nearly 

 all being disti-ibuted both to ampullse of Lorenzini and to neuro- 

 masts. The first branch is probably the equivalent of the ramus 

 oticus (Plate LXVIII. fig. 1, R.O.). It passes upwards and 

 caudad, and divides into two branches outside the orbit, one of 

 which supplies the first neuromasts of the infra-orbital canal, 

 while the other bends outwards to supply neuromasts in the 

 post-orbital portion of the same canal. Two minute branches 

 (Plate LXVIII. fig. 1, R.O.c.) were traced to the skin, so that 

 the ramus oticus contains general cutaneous fibres. Herrick 

 thinks that the r. oticus is the dorsal branch of the Facialis, to 

 which lateralis fibres have been added, and that the presence of 

 cutaneous fibres determines the identity of this ramus. From the 

 relations of the r. oticus to the buccalis — a lateralis ganglion — 

 it seems more probable that the ramus was primitively lateralis, 

 and that to it cutaneous fibres have been added. Should we not 

 be more likely to find the dorsal branch of the Facialis in con- 

 nection with the other portions of the true facial nerve ? If the 

 term r. oticus is to be confined to a ramus which supplies- 

 neuromasts in the first portion of the infra-orbital canal but does 

 not supply any neuromasts in the descending post-orbital part of 



