No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 633 
the hind edge of the infraorbital canal behind the eye, and 
there turns downward and reaches the mandible. A nerve in 
Esox corresponding in position to this nerve in Gadus inner- 
vates a line of surface organs lying on the upper jaw imme- 
diately below the infraorbital canal. In Polyodon the maxillary 
branch of the hyomandibular canal (No. 19, p. 512) may repre- 
sent this line. 
Although certain portions of the canal lines of Amia are thus 
represented in teleosts by lines of surface organs, and vice versa, 
I find nothing in the literature at my disposal that tells defi- 
nitely whether the organs in such cases change in character ; 
that is, whether the organs found on the external surface in 
teleosts, in lines that are represented in Amia by canals, have 
the character of canal organs, or of pit organs, or of some inter- 
mediate or different form of organ. Indirectly one is led to 
conclude that they retain or acquire an intermediate character, 
for Leydig includes them with pit organs and terminal buds, 
under the general term “ Becherorgane.”’ He also states, defi- 
nitely (No. 74, p. 125), that “freie Sinneshiigel zu solchen 
werden kénnen welche in Schuppencandlen liegen”’ (No. 
74, p. 90), that the “ Becherorgane”’ tend to differentiate into 
several distinct groups, and that this differentiation, or tendency 
to differentiate, is more strongly marked in Amphibia and in 
reptiles than in fishes. He, however, places together, under the 
general term “lateral organs,” the canal organs, and the canal 
organs only, in fishes, and the surface or exposed nerve hillocks 
of the lateral lines in Amphibia (No. 74, p. 106), thus making 
a distinction between these exposed lateral organs in Amphibia 
and similar ones found in fishes. He says, however, as does 
Wiedersheim (No. 128, p. 298), that between the several kinds 
of organs, canal organs included, there are so many interme- 
diate forms that it is impossible to draw a sharp limiting line 
between any of them. 
Wiedersheim says (No. 113, p. 298) that nerve hillocks, in 
their development, pass through the stage represented by the 
terminal bud, and that the latter is, therefore, the oldest phylo- 
genetically of all these organs. That being so, what has been 
established for the development of nerve hillocks and the nerves 
