THE CEANIAL NEEVES .AND LATERAL SENSE ORGANS OF FISHES. 173 



Elasraobranohs, althoiigli I made a statement to that effect in uiy Chinicera paper 

 (46, p. 663). I find in my notes on tlic Skate [Itaki bdlis) that a large nerve arises from 

 tlie hyoniandibnlar ti'unk just ontside the auditory capsnle, which, passing ahnost 

 straight backwards, gradually acquir^'s a sujierflcial position, courses over the visceral 

 clefts, and ends on the skin of the hack in that region *. It seems to me that this 

 nerve is the representative of tlie accessory lateral iu the Skate Fourthly, as described 

 and figured by Stannius, the accessory lateral passes extenud to the lateralis lateral line 

 nerve. Pinally, and most important, the large posterior or vagal root is completely 

 overlooked, whicii is the more extraordinary seeing that it also is a text-book fact, and is 

 described and figured by Owen, Parker, and other writers. It must l)e noted, however, 

 tnat Allis is perfectly correct in the more essential considerations — first in homologising 

 the Siluroid " recurrent facial " with the accessory lateral system of tlie modern Teleosts, 

 and second in regarding the latter as a somatic sensory and not a special sensory or 

 lateral line nerve. 



Allis (1897, 6, p. 599), after describing two ])ranches of the ophthalmicus trigemiui 

 which seem to me to correspond to the anterior or trigtMuino-facial root of the accessory 

 lateral system of Gadus, writes as follows (p. 691) : — " Its [the vagus's] small intracranial 

 branch arises more from the main vagus root than i'rom the dorsal branch itself. It, 

 however, arises from the fibres that go to form, that hrancli, a ltd hence can be considered 

 as a branch of it. It runs upward and forward, internal to the root of the lateral nerve, 

 and issues on the top of the chondrocranium by a small foramen lying near the middle 

 line of the head, near its hind end. Its further course could not be traced. From its 

 position, at its exit, it would seem to be the ramus lateralis trigemini, or ramus recurrens 

 facialis, of Teleosts. Its apparent origin is, however, from tlic vagus, and not from the 

 trigeminus or facialis. If it be the ramus lateralis trigemini, the first pair of dorsal 

 branches of the ophthalmicus superficialis trigemini cannot be that nerve, or can only be 

 a part of it. Botli nerves, and the main supra-temporal as loell, are distributed to regions 

 where terminal buds are formed, this being espjeciaUy true of the posterior branch of the main 

 nerve."'' (Italics mine.) Here it will be seen that Allis contradicts his own statement 

 that the accessory lateral nerve of Amia has not an intracranial course (cp. j)]'evious 

 quotation). His failure to homologise definitely his two sets of nerves is due, of course, 

 to his oversight re the roots of the system in Gadus. It is not difficult to recognise his 

 trigeminal branches as corresponding to the anterior root, and his vagal branch to the 

 posterior root of the accessory lateral system, as indeed Allis himself surmised iu his 

 summary (p. 747). 



There seems to be no homologue of the accessory lateral nerves in Protoptertis, 

 according to Pinkus (1891, 157), but the system is briefly mentioned as the "nervus 

 Weberi" in Lota vulgaris by Goronowitsch (1897, 90), where, as one would expect, 

 and as far as Goronowitsch's description goes, it closely resembles the same nerves 

 in Gadus. 



* In tliis connection cp. Jackson & Clarke {187(i, loO). It is possible that the nerves they describe as 

 anastomosing with the tirst spinal nerves may also represent a part of the accessory lateral system. 



21* 



