CRANIAL NERVES OF CHIMERA MONSTROSA. 645 



The larger accompanies one of the divisions of the outer buccal and has the following 

 distribution: — (1) part of it accompanies the outer buccal; (2) just after leaving the 

 orbit a few twigs of it leave the outer buccal and anastomose with the maxillary division 

 of the Vth (fig. 1, V s ) ; (3) some very fine twigs (fig. 1, B 5 ) by a long course either 

 reach the levator of the upper lip, or join with the maxillary in that region. The above 

 constitutes the only confusion or mingling between the facial and trigeminal nerves of 

 Chimsera (see figs. 1 and 3). 



Branches. — I distinguish five branches of the trigeminal of Chimsera, as follows : — 



/, / a n • i i ^i i • t" Dorsal " sensory branches. 



(b) superficial ophthalmic J J 



(c) Maxillary (prae-branchial). 



(d) Mandibular (post-branchial). 



(e) Pharyngeal or visceral. 



(a) Profundus. — This nerve, which represents the non-ganglion ated nasal nerve 

 of man, is one of the most interesting nerves in Chimsera. It has a most undoubted 

 origin from the trunk of the trigeminus, and cannot be separated or dissected away 

 from it. I am therefore, in the absence of definite proof to the contrary, describing it 

 as a branch of the Vth. It arises from the main trunk somewhat proximal to the 

 Gasserian ganglion, and soon after expands to form the profundus or " mesocephalic " 

 ganglion. It then courses forwards and upwards under the superior and internal recti 

 and superior oblique straight across the orbit, first giving off a twig to the ciliary 

 ganglion. When about two-thirds across it gives off a small but conspicuous branch 

 (which may immediately divide into two) ; and this branch, running in a canal bored in 

 the cartilage of the cranium, passes over the superficial ophthalmic of the facial, and 

 eventually reaches the skin in front of the orbital region. Here, after giving off several 

 twigs to the skin, it was eventually traced with much difficulty through a tough fibrous 

 tissue, and found to innervate two sense organs of the supra-orbital canal (marked green 

 in fig. 1). This was seen in both my specimens. 



Passing on, the profundus enters the cartilage of the cranium, and, still in the 

 cartilage, courses upwards to pass over and become wrapped round the ventral surface 

 of the superficial ophthalmic of the facial. It can be separated from this for a short 

 distance, but finally becomes inseparably fused with it. After the profundus had 

 become opposed to the facial, but arising distinctly from the profundus, a thin nerve is 

 observed to separate out, and to run straight down so close to its fellow of the opposite 

 side that both may be dissected at the same time. This interesting nerve is found, 

 after a very long course, to break up on the outer surface of the inner wall of the 

 nostril. From my notes, I must have regarded this as a sensory nerve, but its origin 

 and distribution make it exceedingly probable that it corresponds to the motor division 

 of the profundus found in Cyclostomes. Possibly, further investigation will establish 

 the motor character of this nerve in Chimsera. 



