No. 3-] LATERAL LINE OF AMIA. 491 
XL., p. 22, z, 7), which is the undivided original double pore 
formed by the fusion of the posterior peripheral system of the 
head with the anterior one of the lateral line. Although com- 
pressed and flattened and hidden from view under an overhang- 
ing fold of dermis, this pore is the largest one in the entire 
lateral system of Amia. 
The peripheral system of the first scale is always more or 
less aborted. In the 27-inch specimen it had but two pores on 
one side of the body and four on the other, and in the 17 and 
201 inch specimens but one pore on each side. In several 
other specimens there were no pores at all in this system, the 
scale projected but little beyond the hind edge of the supracla- 
vicula, the end of it being cut squarely off across the line of the 
canal so that the exposed portion was triangular in shape, with 
a straight edge behind. 
There were, in the several specimens in which they were 
counted, sixty-seven or sixty-eight full scales in the lateral line. 
In the second scale of the line there were, in the 17-inch 
specimen, seven openings; in the third, six ; and in the fourth, 
seven. In the 27-inch one (Fig. 39) there were eight in the 
second scale, twelve in the third, and eleven in the fourth. In 
the following scales, for about half the length of the line, 
the peripheral systems are fairly constant and regular; but 
behind that there is great irregularity, some of the scales, and 
often several in succession, having no pores at all, and nearly all 
of them having a much smaller number than those in the first 
half of the line. Toward the tail there are usually but one or 
two pores in a scale (Fig 3, b, Pl. XXX.), and the development 
here is often so greatly arrested that the lateral canal, through 
one or more scales, is an open channel. 
Behind the last full scale of the line the canal turns slightly 
downward, and enters the tail fin between two of its rays. It 
then runs straight backward about three-fourths the length of 
the fin, and ends in a single terminal pore, which is usually 
closed secondarily. Along this part of the canal there is only 
a single row of pores, those toward the end of the line being 
small, and often closed. 
3. Supra-orbital Line. — Group 1 of the supra-orbital line lies 
near the base of the nasal tube, close to the dorsal edge of the 
dermal crease, which extends backward from it. There are 
