568 Studies in ttie Theory of Descent. 



west of the United States (Wyoming Territory), 

 and obtained from them, by breeding in aquaria, 

 Amblystoma Mavortium (Baird). He considers 

 it indeed doubtful whether the Amphibian under- 

 goes this transformation in its native habitat, 

 although he certainly states this opinion without 

 rigorous proof on purely theoretical considerations, 

 because, according to his view, " the low tempera- 

 ture is there less favourable." 8 



If I throw doubt upon this last statement it is 

 simply because Amblystoma Mavortium is found 

 native in many parts of the United States, viz : 

 in California, New Mexico, Texas, Kansas, 

 Nebraska, and Minnesota. It is indeed by no 

 means inconceivable that in the mountain lakes 

 where Marsh obtained this species, it may behave 

 differently with respect to metamorphosis than in 

 other habitats, and this appears probable from 

 certain observations upon Triton which will be 

 subsequently referred to. 



Meanwhile, in the absence of further observa- 

 tions, 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 transfor- 

 mation, although it is at least established that this 



8 Proc. Boston Soc., vol. xii. p. 97 ; Silliman's Amer. Journ., 

 vol. xlvi. p. 364. I have not been able to get a copy of this 

 paper, and quote from a reference in " Troschel's Jahres- 

 bericht." See preceding note. 



