278 , MR. W. B. COLLINGE ON THE [Apr* 2, 



region the nerve divides into two branches, each of these again 

 di^^ding into nvimerous fine twigs. 



2. The ramus huccctlis suppHes all the sense-organs of the sub- 

 orbital branch. It branches from the Gasserian ganglion above 

 the ramus maxillo-mandibularis, to which it is connected by a fine 

 branch. It passes forwards, crossing the floor of the orbit, and 

 terminates in a series of fine branches. In its course forwards it 

 gives off a series of fine branches which supply the sense-organ,s 

 between the pores 10 to 15. 



3. TJie ramus oticus innervates the greater portion of the main 

 canal and the backwardly directed branch of the supra-orbital 

 branch which terminates at pore nmnber 9 (fig. 1). The ramus 

 oticus passes above the facial (PI. XVIII. fig. 1, r.ot.) and divides 

 into two branches ; the main branch passes backwards along the 

 main canal and the other makes a lateral curve forwards and 

 supplies the small branch which is given off from the supra-orbital 

 branch and terminates at pore 9. 



The Facial Nerve. — The only branch entering into connection 

 with the sensory canal system is the ramus mandibularis. This 

 nerve arises as a branch of the ramus hyomaudibularis. The latter 

 nerve traverses a canal in the hyomandibular bone, some little 

 distance below which it divides into two ; the ramus hyoideus 

 passing ventrally and the ramus mandibularis forwards, giving off 

 numerous branches to the mandibular portion of the operculo- 

 mandibular branch of the sensory canal. 



The Glossopharyngeal Nerve in C. magur does not run or arise in 

 conjunction with the vagus, as Pollard (11. t. 35. fig. 1) has 

 figured in Clarias, sp. In all the specimens examined I find it 

 arises slightly dorsal to, and qmte distinct from, the vagus. Its 

 anterior branch passes dorsally, and the posterior one to the 

 posterior portion of the main canal of the head. 



The Vagus. — The ramus lateralis vagi passes off from the vagus 

 as a lateral division. It sends off a short branch which passes to 

 the commencement of the main canal ; it then proceeds outwards 

 and backwards, giving off a series of fine branches, which pass 

 between the muscles and supply the sense-organs in the anterior 

 region of the lateral canal. 



2. AMITmUS CATTTS. 



General Description. 



The sensory canal system of this fish has been briefly described 

 by Eamsay Wright (12) and is also referred to by AUis (1). Yery 

 briefly I will give a summary of the observations of these two 

 writers in order that I may not have to point out at any length 

 the differences between our respective accounts. 



The references made by AUis are very brief. Speaking of the 

 operculo-mandibidar canal in Amia he says (p. 473) : " The 

 mandibular and opercular portions of the canal develop as two 

 distinct canals, uniting later with each other to form a continuous 



