The Latero-Sensory Canals and Related Bones in Fishes. 471 



orbital line, and not merelj^ an anterior, canal part of it, thus 

 here anastomoses by its hind end with the main infraorbital. Imme- 

 diatelj^ anterior to this point of anastomosis there is, in the infra- 

 orbital canal, a group of organs that are separated, by their inner- 

 vation, from the still more anterior organs of the line; and this group 

 of organs in this fish probably corresponds to the single postfrontal 

 organ of Amia. The otic section of the main infraorbital canal ex- 

 tends from the point of anastomosis of that canal with the supra- 

 orbital canal, backward to the supratemporal canal, there thus being, 

 anterior to the supratemporal canal, no section of the main infraorbital 

 canal that is innervated by a postfacial nerve. The supratemporal 

 canal thus has, in this, relations to the main infraorbital canal that 

 correspond more to the middle head line of pit organs of ganoids 

 and teleosts than to the supratemporal canal. The sense organs of 

 the canal are innervated, as those of the supratemporal canal are in 

 ganoids and teleosts, by the first, or supratemporal branch of the 

 nervus lineae lateralis vagi; but this nerve, it should be noted, may, 

 as in Scomber, contain fibers that, in Amia, issue with the glosso- 

 pharyngeus. A short section of the lateral line canal, lying immediately 

 posterior to the supratemporal commissure, is perhaps innervated by 

 a branch of the glossopharyngeus. This I could not definitely 

 determine. There is, in a diverticulum of the spiracular cleft, a 

 modified epithelium, innervated by a branch of the ramus oticus, that 

 epithelium doubtless representing the spiracular latero-sensory organ 

 of Amia and of Lepidosteus. The so-called median canal, in Garman's 

 terminology, is longitudinal in position and lodges two parallel rows 

 of sense organs. There are thus here two parallel canals that have 

 touched and coalesced for a certain distance. In Acanthias and 

 Pristiophorus these two canals here lie close together and parallel to 

 each other, but they do not touch hi any part. 



Raia batis differs from Mustelus in that the entire section of 

 infraorbital canal that is innervated, in Mustelus, by the ramus oticus 

 facialis is said to be innervated, in Raia, by an anterior branch of 

 the supratemporal branch of the nervus lineae lateralis vagi; this 

 being, if correct, a wide departure from what is known in other fishes, 



