532 H. B POLLARD, 



in which it turns and runs backwards. There was no communication 

 with the opposite side. In Fig. 2, this canal is represented diagrama- 

 tically as if seen through the head. The first sense organ is rudi- 

 mentary. The next four pores and sense organs lie in the lower jaw, 

 in the dentary and articular bones and occur at fairly regular inter- 

 vals. The sixth pore lies at the articulation of the lower jaw. Thence 

 the canal is continued backwards and upwards in the preopercular 

 bone lying outside the quadrate. Sense organs 6, 7, and 8 offer no 

 special peculiarity. The branch given off between the 7th 

 and 8th organs is stouter than the average, runs out- 

 side the inter operculum and branches dichotomously 

 opening at pores 8 a and 8 b. The last portion of the canal lies in 

 the dermis outside the dilatator operculi muscle and gives off one more 

 branch to the 9 th pore. The opercular canal joins the main canal 

 just above the articulation of the hyomandibular with the pterotic. 

 There are therefore in the operculo-mandibular system 8 sense organs 

 and 9 pores one of the latter being double. 



Innervation. The infraorbital system is supplied by the Ra- 

 mus buccalis which gives off a twig to each of the 5 sense organs. 

 The buccalis lies remarkably far removed from the surface and the 

 twigs which supply the two posterior sense organs are long and pass 

 transversely outwards. The supraorbital system is supplied by the 

 ophthalmicus superficialis. The nerve to the first sense organ curves 

 under the canal and approaches the organ from the median side. The 

 twigs to the 3rd and 4th sense organs run upwards and slightly back- 

 wards the ophthalmicus superficialis in this region lying deep down. 

 It has a common origin with the buccalis. 



The fifth sense organ is supplied by a nerve which runs to it 

 intracranially apparently quite separate from the ophthalmicus super- 

 ficialis. 



The sixth organ of the main line is supplied by the Ramus oticus 

 which arises dorsally from the large ganglion and passes through the 

 cartilage and pericliondrial bone just in front of the curve of the an- 

 terior semicircular canal. From the same portion of the ganglion arise 

 nerves (Fig. 2, x and «/) corresponding to those in Clarias. One branch 

 runs outwards near the infraorbital canal and the other passes medianly 

 to the crown of the head. These two branches do not supply sense 

 organs of the lateral line. 



The seventh sense organ is supplied by the Glossopharyngeus, 

 the eighth and ninth by branches from the Vagus. The first of these 



