41 
does not in the least affect my contention that canals must be defined 
according to the nerves supplying them and not by any structural 
peculiarities of their own. My opponent is stating his own view of the 
case, which may or may not be right, but is not meeting mine. ALLIS 
is disposed to deny that he defines the canals by their innervation 
(although omitting the case of the infra-orbital that is what he 
practically has done in Amia), and says that their names are “based 
on purely topographical considerations”. In the latter case one is dis- 
posed to ask how the canal in Amia containing sense organs 15 to 21, 
situated above and altogether behind the eye, is termed 
infra-orbital. Axnuis is therefore inconsistent in both respects — first as 
regards innervation, and second as regards topographical relations. I 
shall now be interested to learn how the sensory canals are to be 
classified. From my own point of view no classification can have any 
importance, since the whole system is itself a unit and cannot there- 
fore be classified in any but a purely convenient manner. But certain 
facts are stated as opposed to the innervation classification of the sensory 
canals, and these are as follows: 1) A branch of the buccal in Scomber 
is said (for the first time here) to innervate one organ of the supra- 
orbital canal. To quote Atuis’ own words, as I had no access to his 
notes, my failure to take this fact into account is perhaps excusable. 
2) A branch of the profundus in Chimaera is stated on my authority 
to innervate twc organs of the same canal. Here again I must object 
to this observation being quoted apart from its context, and I accord- 
ingly refer those interested to the original paper, where the bearings 
of this apparent anomaly are discussed. 3) Ewarr is quoted as follows: 
“In Selachians in general, according to Ewarr’s schema, that section of 
canal that is defined by him as temporal, is innervated by the branches 
of three nerves, the oticus facialis, the glossopharyngeus, and the lateralis 
vagi.’ I must express surprise, that this quotation should have been 
made. In the schema in question the temporal canal is well defined 
by the lettering 7. T., and is innervated only by the IXth nerve. It 
was inserted solely on the authority of Aruıs’ own work, since Ewart 
himself did not find any branches of the IXth supplying lateral sense 
organs +), nor does he describe a temporal canal in the types investigated 
by him, but distinctly denies being able to delimit one. On p. 70 Ewart 
refers to a temporal canal, but the passage relates to Amia, and toa 
distinct canal innervated, as it was then supposed, by a distinct nerve, and 
not as stated by Auuis by branches of 3 nerves. On the other hand as 
the only statement on which the temporal canal was founded has since 
been dissipated, the canal must also go with it. Finally Ewart himself 
is perfectly logical and consistent in defining the canals according to 
their innervation, his “temporal canal” was a necessary result of this 
consistency, and in my opinion to quote his work in support of the 
opposite view was not permissible. The peculiar views of Auuis there- 
1) This has since been described by Ewart and the writer, but 
a comparison of Ewart’s figure with that given in our joint description 
‘at once suggests that the latter is an anomalous case, whilst also the 
IXth nerve there does not supply a part of Arrıs “temporal canal”. 
Arrıs by the way misquotes this paper in his list of literature. 
