174 ALUS. [Vol. XVIII. 



There it curves sharply laterally, or laterally and backward, trav- 

 erses that part of the frontal that forms the floor of the anterior 

 ends of the supratemporal and temporal grooves, and enters that 

 part of the ridge between the temporal and dilatator grooves that 

 is formed by the frontal bone alone. In this ridge it runs laterally 

 and outward, and issues from the frontal on the dorso-mesial sur- 

 face of the ridge, near its outer edge. There it enters the dermal 

 tissues superficial to the ridge, and running backward and later- 

 ally, superficial to the anterior portion of the otic part of the main 

 infraorbital canal, ends, lateral to that canal, in a single pore. It 

 does not extend beyond the frontal into the parietal as it does in 

 Amia. 



The first dendritic system of the line is the anterior terminal 

 tube and pore of the canal. The tube issues from the nasal bone 

 near its anterior end, and the pore lies on the top of the snout, 

 considerably in front of the single nasal aperture. 



The second and third systems were, on the right side of the fish 

 used for illustration, each represented by two tubes and pores, 

 each tube of each system arising separately and independently 

 from the main canal. On the left side of the same fish each of 

 the two systems contained but a single tube and pore. All of the 

 tubes, on both sides of the head, were directed backward and lat- 

 erally from the main canal. The second system arises from the 

 canal at the summit of the curve that forms the anterior half of 

 the nasal bone; the third system from the summit of the curve 

 that forms its posterior half. 



The fourth system of the line lies between the nasal and frontal 

 bones, arising from that part of the main canal that lies in the 

 open groove on the dorsal surface of the frontal, immediately pos- 

 terior to the nasal. On one side of the fish used for illustration 

 it was represented by two tubes arising close together from the 

 main canal ; on the other side by two tubes arising some little dis- 

 tance apart. One tube in each case ran laterally, outward and 

 forward, the other laterally, outward and backward to the sur- 

 face, the surface openings of the tubes lying slightly posterior 

 to the single nasal aperture of the fish. 



System No. 5 lies at the point where the main canal bends 

 sharply laterally, and was always found as a relatively long tube, 



