132 JOURNAL OF COMPARATIVE NEUROLOGY. 
conclusions here expressed, with one notable exception. Mr. 
EK. P. Atuis (’o1) has recently published an important paper 
on certain features of the sense organs (particularly the am- 
pullae of Lorenzinr) and cranial nerves of Mustelus, which 
takes its departure from our present problem, as indicated from 
the following quotation for the introductory paragraph : 
‘I have long had a very decided impression, opposed to that of 
most workers on the subject, that these ampullary organs must be ge- 
netically related to the terminal buds of ganoids and teleosts rather 
than to the pit organs of those fishes; and I thought that I should 
easily be able to get some positive evidence of this in the general 
course and position of the nerves that innervate them in advanced 
selachian embryos. ‘This positive evidence I have wholly failed to get, 
for the very simple reason that, in the main nerve trunks, I could not 
distinguish in my sections the ampullary fibers from the lateral canal 
ones. Disappointed in this at the very beginning of my investigation, 
I nevertheless decided to quite carefully trace the lateral canals and 
the nerves that innervate them and the ampullae, as far back as my 
sections went, that is, nearly to the level of the first gill slit. Careful con- 
sideration of these observations has fully convinced me, though indi- 
rectly, that the ampullary organs do represent the terminal buds of 
ganoids and teleosts, and not the pit organs.” 
These conclusions have been criticised at some length by 
JOHNSTON (’02) and by myself (this Journal, vol. XII, p. iii) 
but ALrIs (’03) now returns to his original proposition fortified 
by fresh facts from the study of the lateral line system of Polyo- 
don, though the evidence is still all indirect. Fortunately, at this 
time we are able to meet speculation with fact, and, as we have 
seen above, to put the morphology of the terminal buds ona 
secure foundation. 
ALLIS’ argument rests ultimately on two main supports, 
viz.: (1) the supposed homology of the cerebral center from 
which the ampullary organs of selachians are innervated with 
that from which the teleostean terminal buds are supplied ; and 
(2) the supposed similarity of the ampullae themselves and the 
terminal buds. 
(1) On the first point Mr. Artis is able to oppose to the 
observations of all students of selachian nerves that the am- 
pullae are supplied from lateralis branches only the conjecture 
that the twigs for the ampullary organs terminate in the brain 
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