664 MR FRANK J. COLE ON THE 



Amphibia. Since Clarias represents " a very ancient type of the lateral line system," it 

 may be that it is the primitive root of the lateralis, i.e., when this nerve arose from a 

 common lateral line trunk ; but further investigations as to its development and adult 

 anatomy are much needed. 



It is very strange that none of the three authors who have paid special attention to 

 the ear of Chimsera should have observed the very interesting fact that the sacculus 

 contains a hard calcareous otolith. I have seen it in three specimens, and both surfaces 

 of it are shown in figs. 4 and 5. Breschet (1) says that "il [i.e. the sacculus) contient 

 aussi de cette matiere amylacee, que nous avons nomme otoconie, et une liqueur blanche," 

 and this is his only reference to the otolith. Leydig (7) figured and described several 

 otoliths in Chimsera, which were soft, round, calcareous bodies, formed of concentric 

 laminae, and somewhat resembling starch granules. Finally, Eetzius (29) figures and 

 describes exactly the same bodies as Leydig. As it is hardly probable that Leydig 

 and Retzius should both have made the same mistake, it seems to me desirable that 

 the otolith should be investigated in both genera of Chimaeroid fishes. At present 

 Chimsera must be regarded as the only cartilaginous fish having a hard otolith. 



J. The Glosso-pharyngeal, or Ninth Cranial Nerve (fig. 2). 



Before proceeding to the IXth and Xth cranial nerves, it is necessary that I 

 should briefly describe the arrangement of the gills. There is a hyoid and five branchial 

 arches in Chimsera. These are so situated in the empty pharynx that the edges 

 bearing the gills point obliquely backwards. These edges are therefore the posterior 

 edges. There is one gill to each arch, consisting, as usual, of two demi-branchs. The 

 hyoidean or opercular gill and the gill on the fourth branchial arch, however, consist 

 of a single demi-branch each. The last or fifth branchial arch, of which only the basi- 

 and cerato-branchial elements remain separate, has no gill whatever, and I did not 

 succeed in tracing any branch of the vagus to it. This must, however, exist. The 

 breathing apparatus of Chimsera therefore consists of eight demi-branchs, arranged 

 so as to form five gills, innervated by four nerves — the glosso-pharyngeal and three 

 branchial divisions of the vagus. 



The ninth nerve of Chimsera arises from the medulla by one large root and two 

 small rootlets below and under cover of the anterior rootlets of the lateralis, as in all 

 cartilaginous fishes (see fig. 2). It passes through the cranium by a separate foramen, 

 and immediately expands into an obvious ganglion. From this ganglion the very fine 

 dorsal branch arises (IX 1), which does not, however, innervate any sense organs of the 

 lateral line, but passes straight upwards to the skin of the occipital region. The glosso- 

 pharyngeal then passes on, and divides into the following branches : — 



(l) Prse-branchial (IX 2). — Courses at the base of the first or hyoidean or opercular 

 demi-branch. After reaching the base of the hyoid arch, it becomes at first thin and 



