1. The gills disappear; the gill-clefts close up, and of the branchial arches only the foremost remain, the posterior ones disappearing. At the same time the os _hyoideum_ becomes changed (Duméril). 2. The dorsal crest completely disappears (Duméril). 3. The aquatic tail becomes transformed into one like that of the salamanders (Duméril), which, however, is not as in the salamander cylindrical, but somewhat compressed laterally (Weismann). 4. The skin becomes yellowish white, irregularly spotted on the sides and back (Duméril), whilst at the same time its former grey-black ground-colour changes into a shining greenish black (Weismann); it loses, moreover, the slimy secretion of the skin, and the cutaneous glands become insignificant (Kölliker). 5. The eyes become prominent and the pupils narrow (Kölliker), and eyelids capable of completely covering the eyes are formed; in Axolotl only a narrow annular fold surrounds the eyes, so that these cannot be closed (Weismann). 6. The toes become narrowed and lose their skin-like appendages (Kölliker), or more precisely, the half webs which connect the proximal extremities of the toes on all the feet (Weismann). 7. The teeth are disposed in this species, as in all other _Amblystomæ_, in transverse series; whilst in Axolotl, as in _Triton_ larvæ, they are arranged at the sides of the jaw in the form of a curved arch-like band beset with several rows of teeth.[238] (Duméril. See his fig., _loc. cit._ p. 279). 8. In Axolotl the lower jaw, in addition to the teeth on the upper edge of the bone, also bears “de très petites dents disposées sur plusieurs rangs;” these last disappear after metamorphosis (Duméril). I will add that the persistent teeth belong to the _os dentale_ of the lower jaw, and those that are shed to the _os operculare_.[239] 9. The surface of the posterior moveable part of the body is slightly concave both before and after transformation; the anterior part is, however, less concave in _Amblystoma_ than in _Siredon_ (Duméril). I have not yet been able to verify Duméril’s 7th and 9th statements, as I did not want to kill any of my living Amblystomas,[240] simply in order to confirm the observations of a naturalist in whom one may certainly place complete confidence. Neither have I as yet observed the transformation of the branchial arches, but all the other statements of Kölliker and Duméril I can entirely corroborate.