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1. A very large branch to the muciferous tube system (Savi). 
2. The mucous membrane of mouth. 
3. One to the muscles of the jaws from which the small branch, 
4, Going to the organ just described, is derived. 
On the following grounds, therefore, is based the opinion, that this 
little organ is truly the homologue of the electric organ of the torpedo : 
its position and relative anatomy, its structure, its nervous supply; and, 
moreover, that I have not found it present in the torpedo, which, through 
the kindness of Dr. E. Perceval Wright, I have had an opportunity of 
dissecting. 
Let me state, however, with reference to this last assertion, that I am 
unable to say positively that the organ in question does not exist in the 
torpedo ; for, in those which are to be found in the museums of Dublin, 
it is possible that they may have been removed in the dissections already 
made, which may also have been the case in that placed in my hands 
by Dr. E. Perceval, Wright. F 
Tf further research shall show that these organs co-exist in the torpedo 
with the electric batteries, then, of course, the idea of them being ho- 
mologous organs falls to the ground. 
It may occur to some, also, as it did at first to myself, that the bodies 
which I have described may be related to the ‘‘ follicular nervous appa- 
ratus” (‘‘ appareil folliculaire nerveux”? of Savi), existing in the torpedo, 
but not in the non-electric rays; but I conceive that the consideration of 
the structure and nervous supply is sufficient to negative such a notion. 
In that chapter of Mr. Charles Darwin’s book on the ‘‘ Origin of Spe- 
cies,” in which he speaks of those difficulties on the theory of descent 
with modification, some of which are so grave, that he tells us that to 
this day he cannot reflect on them without being staggered, and which 
have much more than staggered many of his readers, the learned author 
mentions the electric organs of fishes as a case of special difficulty. 
Here wasa case, indeed, of special difficulty, obvious to every reader. 
How, on the view of common descent, could we conceive, that while 
these wondrous organs were brought to such a condition of development 
and power in the torpedo, that in the immediate members of the same 
family, no trace of such structures was known to exist ? 
It seemed impossible, or at least in the highest degree improbable, 
that if the Raiide had, in even countless ages past, sprung from a 
common ancestor, the electric batteries of the torpedo should be without 
their homological representatives in other rays. Yet no candid inquirer 
could grant that either the mucous tube apparatus, the lateral line sys- 
tem, or indeed the pseudo-electric tail-organs, fulfil the necessary condi- 
tions. 
Considering, then, the great size and peculiar origin of the nerves 
going to the electric organs of the torpedo, it seemed that a very close 
and accurate dissection of the corresponding nerves of the skate was 
likely to afford some clue to any atrophied or modified electrical appa- 
ratus, if any such existed in that animal: by following this course, I have 
made out the organs already described. 
