CRANIAL NERVES OF CHIMERA MONSTROSA. 657 



to heave devoted most attention to the hyomandibular, which he considered the whole of 

 the Vllth, and which he describes in the following passage (p. 65) : — "Was Chimsera 

 anbetrifft, so gelangt der mit dem grossten Theile des N. trigeminus ausgetretene N 

 facialis cum palatino auf den Boden der Augenhohle und spaltet sich in drei Zweige. 

 Von diesten tritt der R. palatinus am meisten vorwarts aus. Die anderen beiden Aeste 

 sind der R. hyoideus und R. mandibularis. Jeder tritt durch eine besondere Oeffnung des 

 Augenbodenknorpels. Der R. hyoideus erstreckt sich iiber den Unterkiefer, verbindet 

 sich mit einem Zweige des R. mandibularis, gelangt zwischen Unterkiefer und Zungen- 

 bein und vertheilt sich hier an hautigen Gebilden und an der Zunge. — Der Ramus 

 mandibularis sendet nach seinem Durch tritt zahlreiche Zweige an die unter dem Augen- 

 bodenknorpel liegenden Muskeln und namentlich in die Constrictoren der Kiemenhohle. 

 Ein vorderer Zweig, der eigentliche R. mandibularis, geht quer weg iiber den Unter- 

 kiefer und den unteren unpaaren Lippenknorpel, verbindet sich mit Zweigen von 

 Unterkieferaste des N. trigeminus und vertheilt sich an der Unterlippe und an der 

 Haut und den Muskeln der Lippenknorpel." It will be seen from the above quotation 

 that Stannius' description hardly agrees with mine. He is somewhat ambiguous in his 

 description of the ' R. mandibularis ' of the facial. From its origin, one would imagine 

 that he was describing the chorda tympani, but its distribution makes it certain that 

 the ' R. mandibularis ' of Chimeera is the external mandibular. His omission to figure 

 the chorda confirms this conclusion. Stannius figures the buccal nerve somewhat fully, 

 but only barely mentions it in the text (pp. 43-4). He shows more or less completely 

 both inner and outer buccal nerves with their ampullary branches, and also figures a 

 large ventral branch (unlettered) from the buccal trunk, which, unless it be the outer 

 division of the outer buccal, I do not exactly understand. He refers to the orbital 

 sensory canal twigs from the superficial ophthalmic as ' frontal ' branches, and points 

 out that there is in Chimsera no recurrent branch of the facial as found in Teleostean 

 fishes. 



Homology of the Chorda Tympani. 



The question of the homologue of the chorda tympani in fishes is a difficult one to 

 decide, but I think that Balfour's original suggestion* that the pras-branchial division 

 of fishes represents the chorda of mammals has the support of most of the facts. 

 Stannius, who was the first to prove that the Vllth was a branchial nerve associated 

 with the spiracle, classified the facial as follows, the hyomandibular trunk giving off — 



(1) Palatine with prse-spiracular or prw-branchial branches to spiracle. 



(a) External mandibular to lateral line. 



(b) Internal mandibular or motor portion. Con- 

 tinued ventrally on to pharynx. 



Which of these branches Stannius homologised as the chorda tympani is not quite 

 clear (see pp. 68-9). but it is certain that the 'internal mandibular' is clearly dis- 



* Comp. Emb., vol. ii. p. 378. 



(2) Hyoidean or Post-Branchial 



