534 H. B. POLLARD, 



then curves ujjwards and joius the supraorbital canal simultaneously 

 opening at a large double pore. In the curve lies the third sense 

 organ. There are thus 4 pores and 3 sense organs in this system. 



Supraorbital canal. The first pore lies at some little distance 

 anterior and median to the front tubular opening of the nose and the 

 first sense organ is found close to this structure. The second pore is 

 close to the posterior nasal opening. So far the canal has curved 

 outwards. Now however it takes a sharp turn inwards to the third 

 pore which lies between the eyes above the frontal bone. The second 

 sense organ is near this pore. Again the canal curves outward to the 

 double pore at the junction of supra- and infraorbital systems having on 

 its way the third sense organ. There are four pores and three sense 

 organ in this system. 



Main canal. The main canal continues backwards in the post- 

 frontal possessing in that bone one sense organ No. 4 and opening 

 by a pore at its hinder edge. In the squamosal it curves somewhat 

 inwards. Sense organ 5, pore 5, sense organ 6 follow regularly, the 

 last two structures being near together. Beyond the 6 th sense organ 

 a remarkable phenomenon occurs not as far as I know hitherto recorded 

 in any other animal. The canal widens to three lines its diameter and 

 forms a regular sac inside not in the bone (the "suprascapular"). 

 Beyond this sac pore No. 7 in seen followed by sense organ 7 and 

 pore 8. 



Opercular canal. There is no canal in the mandible and in 

 the preopercular region only a small canal is found with three pores 

 and two sense organs. These lie beneath the eye. The direction of 

 the canal is sharply upwards. 



Innervation. The three sense organs of the infraorbital line 

 are supplied by three nerves which represent the buccalis in this 

 animal. They take separate courses only arising together from the 

 same ganglion. 



The first sense organ of the supraorbital canal is supplied by a 

 twig approaoliing it from the median side. Sense organs 2 and 3 are 

 supplied by twigs which do not curve backwards,, this indicating that 

 probably they have not shifted their position at all during their 

 development. The ophthalmicus superficialis gives off a number of 

 sensory branches to the skin in addition to the twigs to the sense 

 organs. 



Organ No. 4 on the main canal is supplied by a Ramus oticus 

 which has an origin quite independent of the buccalis. It arises dor- 



