No. 3.] LATERAL LINE OF AMIA. 465 
Sagemehl’s description is much the best and most complete 
of all; but he does not give the smaller branches of the sys- 
tem, simply saying of them that the main canals have numer- 
ous branches, arranged in many longitudinal rows and leading 
to minute openings on the outer surface of the head. These 
small branches are similarly disposed of in his description of the 
cranial canals in the Characinidz, where he says they are too 
variable and irregular to have any morphological significance 
whatever. 
A closer examination of Amia has shown that these small 
branches have as constant relations to the dermal bones as the 
main canals have, and hence may have as great significance. 
They also have constant relations to the sense-organs found 
in the canals, agreeing in this with the conditions described by 
Bodenstein in Cottus gobio (No. 3) and by Emory in Fierasfer 
(No. 5, p. 39). 
The drawings for this paper have been made by Mr. Nomura, 
to whose patience and skill the plates bear witness. 
I. ADULT FORM. 
General Description. 
If an adult specimen of Amia calva be examined, many hun- 
dreds of minute pores will be found, scattered to all appearance 
most irregularly over a large portion of the head (Figs. 20, 21, 
and 22, Pl. XXXVI.). Most of them lie directly superficial to 
the dermal bones ; and they are found in greater or less num- 
ber external to all these bones, excepting the prefrontal, max- 
illary and jugal, operculum, sub- and interoperculum, branchi- 
ostegal rays, and gular plate. They are also found in certain 
places beyond the limits of the dermal bones; as, for instance, 
near the posterior nasal aperture, in the fold of dermis imme- 
diately behind the pre-operculum, and in the thick dermis 
between the pre-operculum and the hinder and lower margins 
of the postorbitals. In these places they lie mostly near the 
edges of the bones, and are particularly numerous along the 
anterior edge of the pre-operculum. 
Each pore, as is well known, is the external opening of a 
small epidermal tube which leads inward through the dermis 
