ON CHANGE OF MEXICAN AXOLOTL TO AN AMBLY STOMA. 355 



Nebrasta, and Minnesota. Nevertheless, it is by no means incredible 

 tbat just in the Alpine lakes, from which Marsh obtained it, the species 

 occupies a diflerent position in regard to the transformation from what 

 it does in other habitats. This will be seen from the observations on 

 the Triton adduced below. So, until further observations are made, I 

 believe we must suppose that the Paris Axolotls are not Siredon liche- 

 noides, but probably a new and very closely related species. 



Meanwhile, there is not much depending upon this in the review of 

 the transformation, if it is only established that this Axolotl in its home 

 does not undergo the metamorphosis, or only does it as exceptionally 

 as in Europe. Unfortunately, there is in Dum^ril's comniunications no 

 precise statement of the locality where this "Mexican" animal was 

 lound; probably the locality was unlinown to himself, and so I can 

 only assume on Cope's authority that no Amhlystoma has ever been 

 brought from south of the provinces of Tamaulijias and Chihuahua; 

 that is, from south of the tropic* 



Of that, however, there is no certainty. Much more important is the 

 fact adduced above, that the genuine Axolotl of the lakes around tlie 

 city of Mexico never makes the change to an Amblystoma, but that this 

 species also in isolated cases undergoes the transformation in contine- 

 ment. Now, from this and from the fact that the Paris Axolotls in con- 

 finement are only transformed to the extent of a very small percentage, 

 it maj' be concluded iliat also in its home it is either not transformed at 

 all, or only as an exception. 



But still another seri^ of facts comes very essentially into the account 

 in reviewing this history of transformation : I mean the existence of a 

 considerable number of species of Amhlystoma in nature. In the " Revision 

 der Salamandriden-Gattungen" (Beview of the genera of Salamanders) 

 which Strauch t gave a few years ago, there are represented, accord- 

 ing to the examples of Cope,§ twenty species of the Amhlystoma Tschudi 

 living in North America. Now, although a few of these species are 

 based only upon one specimen, and, therefore, as Strauss correctly 

 says, "must be suppressed in time," yet there is left a whole range of 

 species which certainly live and propagate as Amblystoma, and which 

 have their locality from the latitude of New York to that of New Mexico. 

 Hence there are certainly species of Siredon which, under their natural con- 

 ditions of life, regularly take the Amblystoma form and propagate hi it ; 

 while on the other hand there are at least two species which, under their 

 present natural conditions of life, only propagate as Siredon. It is only 

 another form of expression for this fact when one says the Mexican 

 Axolotl, and the Paris Siredon as well, be this latter named lichenoides 

 or something else, stands upon a lower phyletic stage of development than 

 the other species of Amblystoma which propagate in the salamander 



* Dana and yilliman, Amer. Journ., 3d ser. i, p. 89; Annals of Nat. Hist, vii, p. 246. 

 t Proceedings Acad. Pbilad., xix, 1867, pp. 166-209. 

 $ Mem. Ajad. Petersb., tome xvi. 



