Meanwhile, in the absence of further observations, we must admit that the Paris Axolotls were not _Siredon Lichenoides_, but some nearly allied and probably new species. But little information is furnished by observing the course of the transformation, although it is at least established that this Axolotl in its native habitat does not undergo metamorphosis or does so as exceptionally as in Europe. Unfortunately in his papers Duméril gives no precise statement respecting the locality of this species imported from “Mexico”--it is probable that he was himself unacquainted with it, so that I can only state on the authority of Cope that Amblystoma has never been brought from south of the provinces of Tamaulipas and Chilhuahua, _i.e._ south of the Tropic of Cancer.[233] This last statement, however, gives no certainty to the matter. Of much more importance is the above-mentioned fact, that the true Axolotl of the lakes about the city of Mexico does not, as a rule, become transformed into an Amblystoma in that locality, although this species in certain cases undergoes metamorphosis when in confinement. From this circumstance and from the fact that the Paris Axolotl likewise experienced but a very small percentage of metamorphosis in captivity, we may venture to conclude that this species also, in its native habitat, either does not become transformed at all or does so only exceptionally. But there is yet another body of facts which come prominently into view on considering the history of the transformations. I refer to the existence of numerous species of _Amblystoma_ in a natural state. In the “Revision of the genera of _Salamandridæ_,” published some years ago by Strauch,[234] this author, following Cope,[235] gives twenty species of _Amblystoma_ as inhabiting North America. Although some of these species are based on single examples, and consequently, as Strauch justly remarks, “may well have to be reduced in the course of time,” there must nevertheless always remain a large number of species which live and propagate as true Amblystomas, and of which the habitat extends from the latitude of New York to that of New Mexico. There are therefore true species of _Siredon_ which regularly assume the Amblystoma form under their natural conditions of life, and which propagate in this form, while, on the other hand, there are at least two species which, under their existing natural conditions of life, always propagate as _Siredon_. It is but another mode of expression for the same facts if we say that the Mexican Axolotl and the Paris _Siredon_--whether this is _Lichenoides_ or some other species--stand at a lower grade of phyletic development than those species of _Amblystoma_ which propagate in the salamander form. No one can raise any objection to this statement, while the alternative view maintained by all authors contains a theory either expressed or implied which is, as I believe, incorrect, viz. that the Mexican Axolotl _has remained_