660 MR FRANK J. COLE ON THE 



post-branchial nerves, representing the efferent and afferent lingual fibres of higher 

 vetebrates, and the three accessory viscerals, representing the single visceral nerve of 

 other fishes. 



Literature. — Stannius makes a few very brief references to the glossopharyngeal of 

 Chims&ra (pp. 76, 77, and 78), but does not anticipate the above account in any im- 

 portant respect. He further (p. 70) commits the error of stating that the glosso- 

 pharyngeal passes through the same foramen as the vagus, a mistake copied by 

 Gegenbaur (14), but corrected by Hubrecht (17). Stannius, however, seems to have 

 been the first to describe the dorsal sensory branch of the IXth, which he found in 

 Spinax and Carcharias, and this discovery has been confirmed by Gegenbaur (14), 

 and almost every writer on the cranial nerves of fishes since his time. The fact that 

 this branch ruay innervate a portion of the lateral line system was, I believe, first 

 discovered for Mustelus by Eamsay Wright (34). Allis (49) next described a 

 similar case in Amia, and further found that the dorsal branch of the IXth in this 

 Ganoid had a separate root and ganglion, and passed through a separate foramen in the 

 skull. Pollard (60) describes the dorsal branch of the IXth innervating sense organs 

 in the following Siluroids : Clarias, Trichomycterus, Callicthys, and Auchenaspis. In 

 these fishes the dorsal branch supplied only one sense organ, which ivas homologous 

 throughout all the forms Pollard examined. Finally, Ewart and Cole (66) have 

 described the dorsal branch of the IXth innervating three sense organs of the lateral 

 line in Lsemargus. This variation (?) of the dorsal branch, therefore, must be con- 

 sidered as well established. It is discussed in section C of the present communication. 



K. The Vagus, or Tenth Cranial Nerve (fig. 2). 



If we accept the contention that the vagus is a compound nerve, — and this seems to be 

 the general opinion of zoologists, — the vagus of Chimsera must be considered to represent 

 its most primitive known condition. For without any dissection beyond mere exposure, 

 three of the component nerves of the vagus, besides the IXth, may be readily distinguished. 

 These are the first and second branchials and the intestinal, and their ganglia are seen 

 as slight swellings near the origins of the nerves. The third branchial and its ganglion 

 also form a separate nerve, which however, proximally, lies partly under, but quite dis- 

 tinct from, the root and ganglion of the second branchial. All the four nerves pass 

 together with the lateralis nerve, through the same foramen in the skull, and each arises 

 by a separate root from the medulla which may be dissected without much difficulty. The 

 roots are, however, closely opposed, and lie more or less under cover of the root of 

 the lateralis, which also obscures the root of the IXth. The above condition is 

 most nearly approached by the vagus of Torpedo, a description of which will be published 

 at some future time. The vagus of Chimsera, therefore, must be described as a complex 

 consisting of four perfectly independent nerves. These nerves I propose to describe as 

 Vagi 1, 2, and 3, and the Intestinal. 



