and Kölliker, and more recently by Max Schultze, are not the true homologues of the electric organs of the torpedo, their position, their structure, and nervous supply, lead me to suppose. Indeed, in so far as this last is concerned, it indicates rather an homological relation with the batteries of the gymnotus, which further research may more fully establish. In alluding to the tail-organs of the skate, I may observe, that in the dog-fish I have found, both in the embryo and the adult, what I conceive to be those organs, in an atrophied condition. They give rise to slight eminences, prolonged from near the vent to the tail; and, on transverse section, are seen like narrow chinks in the corion, quite separated from the muscles.
It may occur to some, as it did at first to myself, that the organ which I have described in the skate may represent the "appareil folliculaire nerveux," noticed by Savi, and by him stated to exist only in the electric rays. I think, however, that this apparatus is clearly an appendage of the so-called muciferous tube system; and, agreeing with the views of Leydig, that these appurtenances of the fifth pair are tactile organs, it does not appear that there is any sufficient reason to consider that any homological relation exists between the "appareil folliculaire nerveux" and the bodies in question. In the electric rays which I have examined, I have not found the body which I regard as the homologue of the electric organ; this fact, indeed, taken along with the consideration of the sources from which the nerves of the organ are derived, are the chief points on which the notion rests, that it may be the homologue of the electric organ at all; but one also cannot help observing in its position, with reference to the band of muciferous tubes, the lateral line, the temporal orifice, and the posterior branch of the fifth pair, evidence in support of the same idea. In stating, however, that the organ is absent in the electric rays (or, at least, only represented by their batteries), I should say that I cannot positively assert this; for the torpedos which have come into my hands have all been partially dissected, and it is possible that the body alluded to may have been Removed. I may beg of naturalists who have opportunities of doing so to determine this point with certainty.
The earlier investigators of the anatomy of the axolotl appear to have regarded it as a larval form. This, some of them, as Rusconi, did, judging merely from its external appearance; others, as Cuvier, even after a somewhat minute investigation into its anatomy.
Hunter, it is true, was convinced that they were adult forms, and merited but little the censures passed upon him by Rusconi, who, from constantly studying the salamanders and their metamorphosis, dogmati-
