214 The Under-Water World 



Among some tailed Amphibians the 

 external gills are retained throughout 

 life. The Axolotl of Mexico is perhaps 

 the most interesting .example. The 

 creature, which occurs in the lakes of 

 certain districts of Mexico, where it is 

 farmed for food purposes, retains the 

 larval form with large branching external 

 gills for the whole of its existence, 

 breeding in the imperfect condition. In 

 other parts of Mexico and North America 

 it transforms when a few months old 

 into a black and yellow salamander. In 

 1863 a number of Axolotls that had been 

 imported to Europe from Mexico bred in 

 the Jardin des Plantes in Paris, where 

 the young were successfully reared. 

 It was naturally surmised that these 

 animals, having bred in the branchiate con- 

 dition, must be perfect aquatic animals. 

 Two years later, however, some in- 

 dividuals of the second generation lost 

 their gills and the fins on the back and 



