176 ALUS. [Vol. XVIII. 



tern three tubes and pores had been formed in all the specimens 

 examined, without exception. One of these tubes, in what was 

 considered as the normal arrangement, remained at the bend in 

 the main infraorbital canal, and was a direct continuation of the 

 trunk of the supraorbital system. The other two, resulting un- 

 doubtedly from the dichotomous subdivision of a single tube, had 

 travelled downward along the suborbital part of the infraorbital 

 canal, and appeared as separate tubes of that canal, as already 

 described. In the second arrangement found, it seemed to be the 

 terminal system of the supraorbital canal that fused with the in- 

 fraorbital one, or possibly both that system and the penultimate 

 one. Having been found after the drawings and manuscript were 

 ready for press it was not further investigated. 



After giving off the trunk of system 7 the supraorbital canal, 

 in what was considered as the normal arrangement, makes a 

 sharp, angular bend backward, and continues backward and lat- 

 erally as the eighth or terminal system of the line. Near the ante- 

 rior end of this section of the canal the seventh organ of the line 

 is found, and approximately superficial to this organ the anterior 

 head line of pit organs begins. ' The terminal section of the canal, 

 as already stated in describing the bones, runs backward, outward 

 and laterally in that part of the frontal that forms the anterior 

 part of the ridge between the temporal and dilatator grooves, and 

 then in the dermal tissues superficial to that ridge, passing super- 

 ficial to the otic part of the main infraorbital canal, and ending in 

 a single pore lying lateral to that canal. 



In GaduSj according to Cole's descriptions (No. 16), it is the 

 terminal system of the supraorbital canal that fuses with the in- 

 fraorbital canal, Gadiis differing in this from Amia and also from 

 the larger number of the specimens of Scomber examined. It is', 

 however, to be noted that the penultimate system of the supraor- 

 bital canal of Gadiis is apparently wanting — that is, the system 

 that should be found between organs 4 and 5 of the line — and 

 that this suggests that the terminal and penultimate systems of 

 the line may be fused to form the enlarged hind end of the canal 

 as shown by Cole. If that be so the arrangement found in Gadiis 

 would not differ, in principle, from that found in Amia and most 

 of the specimens of Scomber, and would agree exactlv with what 



