134 JOURNAL OF COMPARATIVE NEUROLOGY. 
that the ampullae of selachians are related to the lateralis and 
not to the terminal bud centers. 
(2) The supposed similarity of ampullary organs and ter- 
minal buds we have already touched upon. The fact is that 
these organs do not resemble each other in their well developed 
adult forms in any known case. In embryonic or reduced con- 
ditions the neuromasts may resemble terminal buds on account 
of the absence or reduction of their hair cells. But even in 
these cases the innervation in all instances where it is accurately 
known removes the ambiguity perfectly. I repudiate most 
emphatically the statement attributed to me by Mr. ALLIs 
(’03, p. 662) that in any fishes nerve hillocks (neuromasts) 
may be innervated by communis fibers. |The exact opposite I 
regard as one of the most important and distinctive of the re- 
sults which I have reached in my studies upon the nerve com- 
ponents of fishes. 
A.tts further argues for the similarity of the two systems 
of sense organs on the ground of the resemblance in the mode 
of the distribution of ampullary organs in very young elas- 
mobranchs to that of terminal buds in adult ganoids (Amia) 
and teleosts. This resemblance in distribution pattern un- 
doubtedly exists, and AtLtis’ demonstration of the origin of 
ampullary organs in the ontogeny of Mustelus diffusely scattered 
over the cutaneous surface in the positions of the mouths of their 
pores in the adult is a point of no small interest and impor- 
tance. His description of pit lines in Mustelus in relations simi- 
lar to the pit lines of ganoids and teleosts is also of importance, 
showing, as I fully agree, that the ampullary organs cannot be 
homologized with these pit lines. 
But it by no means follows because the ampullae are not 
homologous with the pit lines that they are therefore homolo- 
gous with the terminal buds. In fact, my studies of Ameiurus 
have shown that in this type, in addition to lateral line canals 
and pit lines of strictly typical arrangement, there are two in- 
dependent systems of diffusely scattered cutaneous sense organs, 
which I have termed the small pit organs and terminal budsand 
which are innervated by lateralis and communis nerves re- 
