OF GROWTH OF THE LOWER VERTEBRATES. 643 



ie gills persist long after the hind limbs are devel- 

 n). While as a rule the eggs of newts or salaman- 

 1 the water, the red-backed salamander lays its eggs 

 in damp places on land, though the young 

 are provided with gills. Fig. 302 (after 

 Hoy) represents the young of Ambhjstoma 

 lurida on the tenth day after hatching, the 

 lower figure the natural size of the freshly 

 hatched young. In the Surinam toad and 

 Larval Salamander. Hylfl> ^ the is]and of Maurit ius there is no 



metamorphosis, the young hatching with the form of the adult. 

 The Siredon or Axolotl of Mexico, according to Dumeril, lays 

 eggs, though a larva, while, Fig. 303. 



as in the Axolotl, the lar- 



tium, oriffinallv described 

 as an adult animal under 

 the name of Siredon liche- 

 noides (Fig. 303, from Ten- 

 ney's Zoology) has been 

 found by Professor Marsh °"' c " on 01 ,arva ' * ; ™" l,t; '- 



to drop its gills and assume its adult form when brought to the 

 sea level, its original habitat being the lakes situated in the Rocky 

 Mountains at an altitude of 4,500-7,000 feet. 



Professor Owen has well summed up the wonderful changes 

 undergone in these metamorphoses, which arc exactly paralleled 

 by those of the vegetarian larval gnat with biting jaws and gills 

 into the blood-sucking volant, .air-breathing fly; entirely new 

 organs replacing the deciduous ones of the larva, and the body 



phoses of the Batrachia," says the distinguished comparative 

 anatomist, "we seem to have such process carried on before our 

 eyes to its extremest extent. Not merely is one specific form 

 changed to another of the same genus ; not merely is one generic 

 modification of an order substituted for another, the transmuta- 

 tion is not even limited by passing from one order (Urodela) to 

 another (Anoura) ; it affects a transition from class to class. The 

 Fish becomes the Frog ; the aquatic animal changes to the terres- 

 trial one ; the water-breather becomes the air-breather ; an insect 

 diet is substituted for a vegetable one. And these changes, more- 



