34 REPTILES AND BIRDS. 



lives in the lake that surrounds the city of Mexico. They are like 

 stout short-legged Lizards in shape, and are from eight to ten inches 

 in length, and have short extremities, there being four digits to the 

 fore limb and five to the hind. The colour is dark grey, or almost 

 black, with dark spots, and there are three well-developed branchiae 

 on each side of its neck. There are teeth in the jaws, and two lines 

 of them on the vomer. Cuvier had doubts about placing the Axolotl 

 amongst the Amphibia with persistent branchiae, but he stated that 

 so many witnesses gave evidence in favour of the branchiae not being 

 lost during growth that he was obliged to do so. Time and research 

 have produced a curious history about these creatures, and have 

 demonstrated their relation to a perfect and non-branchiate form. 



" The Axolotls furnished with gills reproduce by laying eggs, and 

 at first this was considered sufficient to determine that they were 

 perfect animals, and that no further growth or change was possible. 

 They were placed by zoologists in a genus of the perennibranchiate 

 Amphibia. But in 1865 M. A. Dumeril saw the Axolotls lose their 

 branchiae, and become altered in shape. They resembled In this 

 the Tritons and Salamanders or non-branchiate group, and they 

 became Amblystomes, a kind of Amphibian which has been known 

 before. Some Axolotl eggs turned to creatures like the parent, but 

 after a while they lost their gills and became Amblystomes. The 

 Axolotls can thus become, ' by metamorphosis,' Amblystomes, or 

 adult forms. 



" The immature Amblystoma (the Axolotl) lays eggs, and the 

 perfect form (Amblystoma) is not sterile, but can produce eggs, some 

 of which develop into the usual larval or Axolotl forms, and others 

 into Amblystomes, and the surrounding conditions appear to have to 

 do with the direction of this evolution. The Amblystomes are 

 numerous, and have the skin much folded on the body ; the tail is 

 thick and almost cylindrical at the base. They have palatine teeth 

 forming two transverse rows, which are re-curved, and the tongue is 

 large and fixed infer iorly." 







