The Transformation of the Mexican Axolotl. 585 



That degeneration may also occur from this 

 high stage to a lower stage of development, is 

 shown by many observations on our water-sala- 

 manders. It is known that under certain circum- 

 stances Tritons, as it is generally expressed, be- 

 come " sexually mature in the larval condition." 



In the year 1864 De Filippi 10 found fifty Tritons 

 in a pool at Andermatten, in the neighbourhood of 

 Puneigen, and of these only two showed the 

 structure of the adult water-salamander; all the 

 others still possessed gills, but notwithstanding this, 

 they agreed in both sexes, in size and in the develop- 

 ment of the sexual organs, with mature animals. 

 De Filippi established that these " sexually mature 

 larvae" not only resembled larvae externally through 

 the possession of gills, but that they also pos- 

 sessed all the other anatomical characters of the 

 larvae, i. e. the characteristic bunches of palatine 

 teeth situated on both sides in the position of the 

 subsequent single rows, and a vertebral column 

 represented throughout its whole length by the 

 chorda dor salts. 



According to my view this would be a case of 

 the reversion of the Triton to the immediately an- 

 terior phyletic stage, i. e. to the perennibranchiate 

 stage, and in the present instance the majority of 

 zoologists who take their stand by the theory of 

 descent, would certainly concur in this view. I 



" Sulla Larva del Triton Alpestris" Archivio per la Zoo- 

 logia. Geneva e Torino, 1861, vol. i. pp. 206 21 1. 



