186 EDWARD PHRLPS ALLIS, J UN. 



probably represented in Amia by certain branches that I 

 described as the ramus niandibularis internus trigemini. But 

 these nerves of Amia are probably not represented, in 

 Chimaera, by the so-called ramus pretrematicus of Cole's 

 descriptions. It seems to me much more probable that they 

 are represented in one or both of two other nerves described 

 by Colo. One is the so-called pharyngeal, or visceral branch 

 of the maxillary branch of the trigeminus ; the other a nerve 

 said to be formed by the fusion of three branches of the 

 mandibular branch of the trigeminus. The maxillary branch 

 is said by Cole to curve " round under a large muscle attached 

 to the angle of the upper jaw." The three mandibular 

 branches are said to " curve round and under a corresponding 

 muscle to that which the similar branch of the maxillary 

 curved round." What the muscles to which these nerves are 

 thus related may be is not stated, but the general course of 

 the nerves, so far as given, resembles strongly that of the 

 mandibularis internus trigemini of Amia. If these two nerves 

 in Chimasra are, one or both, the homologue of the nerve in 

 Amia, they must also be the chorda tympani of the fish if the 

 nerve in Amia is. Cole's so-called prebranchial nerve could 

 not then be the chorda, and it might even be found to be a 

 postbranchial nerve, similar to the mandibularis internus 

 facialis of Amia, with which Cole himself homologises it, 

 maintaining, in order to establish his homologies, that the 

 nerve of Amia is a prespiracular nerve (12, p. 205). That 

 this nerve of Amia is not a prespiracular one I have already 

 had occasion to assert (4). 



In seeking the homologue of the chorda tympani in Amia 

 I concluded (3, p. 638), as certain other authors had before 

 me, that it must be a prespiracular nerve. This opinion was 

 said to be based on the course of the " nerve in man through 

 the upper portion of the tympanic cavity, and then downward 

 anterior to that cavity." Cole, however, says (11, p. 660) 

 that " the chorda tympani of mammals passes morphologically 

 under the tympanum." Cole then contends that the nerve, 

 though thus topographically a post-branchial one, is morpho- 



