CRANIAL NERVES OF CHIMERA MONSTROSA. 647 



labial cartilages, and a fairly large bundle, leaving the main nerve, fans out on the nasal 

 sac, and, running over it, its twigs after a long course end in muscles in the immediate 

 vicinity of the external nostrils — some being continued right on to the mid- ventral line, 

 and all terminating near it. The greater part of the maxillary, however, consisting of 

 three bundles, dips down and curves round under a large muscle attached to the angle 

 of the upper jaw. The largest one is the pharyngeal or visceral, and will be described 

 separately later on. Of the two others, one pursued a difficult course and was lost, whilst 

 the other diverged from the pharyngeal on its ventral side, and divided into two. Both 

 of these bundles went straight on to the upper jaw, and pierced it laterally near the 

 dorsal extremity of the lateral set of teeth. They were too fine to be traced through 

 the jaw, but were probably continued on to the mouth. 



(d) Mandibular. — From its origin runs straight clown and courses a little behind 

 the lower jaw. On its way down it gives off numerous branches, mostly to the masseter, 

 but some of them accompany the main nerve, and, after a long course, supply the super- 

 ficial muscles of the ventral region. These are given off posteriorly. There are also 

 several fine posterior twigs, which leave the mandibular just outside the orbit, and end 

 in a relatively small accessory of the masseter attached to the ventral edge of the orbit. 

 A deep motor branch also leaves the anterior edge of the mandibular, just outside the 

 orbit. Not far from the mid- ventral line, the mandibular divides into a loose bundle, 

 and three fairly large nerves. The bundle fans out on the muscles of the lower lip, 

 and the larger portions of it terminate close on the mid-ventral line. The three nerves 

 curve round and under a corresponding muscle to that which the similar branch of the 

 maxillary curved round,. and, after a long course very difficult to dissect, ultimately united 

 on the mandibular bar. The nerve thus formed coursed along the surface of the bar 

 until reaching the mid-ventral line, where it broke up and disappeared in the substance 

 of the bar. The ramifications were too fine to be traced any further, but they possibly 

 found their way on to the mouth. 



(e) Pharyngeal or Visceral. — This nerve, after its origin (described in the section 

 on the maxillary), coursed straight backwards, getting deeper and deeper. It passed deep 

 under the two masseter muscles, and afterwards began to come upwards again. Having 

 reached the lower jaw it passed, after a long course, on to the pharynx [i.e., mouth) at 

 the point where the lower jaw articulated with the skull. It was not traced far on to 

 the pharynx, having by this time thinned very considerably, but there could be no 

 doubt that it innervated a portion of the mucous membrane just inside the mouth. 



Literature. — Stannius figures the Vth nerve of Chimsera ; but as there is only one 

 short paragraph of description, and as, further, he describes the superficial ophthalmic 

 and buccal divisions of the lateral line system as belonging to the Vth, his account of it 

 is somewhat unsatisfactory. There cannot, I think, be any doubt that Stannius simply 

 removed the eye of his Chim&ra, and studied the peripheral distribution only of the nerves 



VOL. XXXVIII. PAET III. (NO. 19). ^ X 



