AMPHIBIANS. 



209 



After what has gone before, the transformation of the 

 Amphibians needs no elucidation. Their predecessors 

 were water-breathers, whose form and mode of life are 

 more faithfully preserved by the long-tailed Amphibians, 

 the tritons, and salamanders, than by the frogs. In 

 our tritons, sexual maturity not rarely commences in 

 the larval state, hence in a phase which was definitive 

 in the progenitors of the present genera. There is, 

 indeed, one species, the Mexican Axolotl, which nor- 

 mally propagates itself during the larval phase. Auguste 



FIG. 18. Ainblystoma. 



Dumeril's observation is highly interesting, that of the 

 thousands of Axolotls that he bred at Paris, some few 

 advanced beyond the grade of development hitherto 

 known in them, i.e. they lost their gills, changed the 



