1895.] SENSOET CA:!«AL SYSTEM OF FISHES. 281 



The whole of the sensory canal system of the head is innervated 

 by the trigeminal, facial, and glossopharyngeal ; the lateral canal 

 is innervated by the lateralis division of the vagus. 



The trigeminal group may be divided into the following main 

 branches, viz. : — 



1. The ramus ophthalmicus superficialis. 



2. The ramus ophthalmicus profundus. 



3. The ramus buccalis. 



4. The ramus maxillaris. 



5. The ramus mandibularis. 



6. The ramus oticus. 



7. The ramus lateralis. 



Of these seven rami all but the rami ophthalmicus profundus, 

 maxillaris, and lateralis innervate some portion of the sensory 

 canals. 



1. The ramus ophthcdmiats superfidalis is with the ramus lateralis, 

 the most dorsal branch of the group. It passes ofE from the 

 Gasserian ganglion immediately above the ramus ophthalmicus 

 profundus, but not, as mentioned by Eamsay "Wright (13. p. 366), 

 through a large foramen. It traverses the dorsal border of the 

 orbit, and then along the upper surface of the skull, supplying a 

 series of cluster-pores in the region of the nasal capsule, and also 

 the sense-organs of the supra-orbital branch. 



2. The ramus ophthalmicKS profunchis lies immediately below the 

 ramus ophthalmicus superficialis ; after passing through the orbit it 

 branches and enters into connection with the ram as ciliaris. 



3. The ramus luccalis arises lateral to the ramus ophthalmicus 

 profundus and beneath the ramus ophthalmicus superficialis. It 

 passes forwards and divides into two branches ; the lateral branch 

 passes along the borders of the sub-orbital branch of the main 

 sensory canal, to which it gives off a number of fine branches ; the 

 inner branch of the buccalis does not innervate any portion of the 

 sensory canal system. 



4 & 5. TJie ramus maxillo-mandihularis. — I cannot agree with 

 Professor EamsayWright's diagram of these nerves^ (13.pl.iv. fig. 1). 

 In the final specimen I dissected, which measured 287 millim. 

 in length, I found the ramus maxillaris considerably larger than 

 the ramus mandibularis ; the buccalis lies just above it (PI. XVIII. 

 fig. 2). A few small branches pass off to the integument, the 

 main branch passing to the maxillary region and innervating the 

 maxillary barblet, on which it divides in four branches, passing 

 between the divided tendon of the retractor muscle. 



TJie ramus mandihularis. — In its upper region it is connected 

 with the ramus maxillaris, dividing into external and internal 

 branches on the anterior edge of the mandibular adductor 

 muscle; the former — the ramus externus — passes along the 

 lower jaw, innervating the mandibular portion of the operculo- 



J- Professor Eainsay Wright informs me that part of the work was done on 

 4. niger, which may possibly accouut for some of the ^fferences. 



