218 THE HISTORY OF CREATION. 
however, they differ externally by the absence of the coat 
of scales. Most gilled Batrachia ive in North America: 
among others of the class is the Axolotl, or Siredon, already 
mentioned. (Compare above, vol. i. p. 241.) In Europe the 
order is only represented by one form, the celebrated “Olm” 
(Proteus anguinus), which inhabits the grotto of Adelsberg 
and other caves in Carinthia, and which, from living in the 
dark, has acquired rudimentary eyes which can no longer see 
(vol. i. p. 13). The order of Tailed Batrachia (Sozura) have 
developed out of the gilled Batrachia by the loss of external 
gills; the order includes our black and yellow spotted land 
Salamander (Salamandra maculata), and our nimble aquatic 
Salamanders (Tritons). Many of them—for instance, the 
celebrated giant Salamanders in Japan (Cryptobranchus 
Japonicus)—still retain the gill-slits, although the gills 
themselves have disappeared. All of them, however, retain 
the tail throughout life. Tritons occasionally — when 
forced to remain in water always—retain their gills, and 
thus remain at the same stage of development as gilled 
Batrachia. (Compare above, vol. 1. p. 241.) The third order, 
the tailless or frog-like Batrachia (Anura), during their 
metamorphosis, not only lose their gills, with which in 
early life (as so-called tadpoles) they breathe in water, but 
also the tail with which they swim about. During their 
ontogeny, therefore, they pass through the course of 
development of the whole sub-class, they being at first 
Gilled Batrachia, then Tailed Batrachia, and finally Frog- 
lie Batrachia. The inference from this is evidently, that 
Frog-like Batrachia developed at a later period out of 
Tailed Batrachia, as the latter had developed out of Gilled 
Batrachia which originally existed alone. 
