466 AMPHIBIA. 



{c) The tongueless Surinam Toad {Pipa americana), in which the eggs 

 develop in pouches on the back of the female ; and the allied 

 Ethiopian genus Xenopus, with a "tentacle" extending back- 

 wards on each side of the head. 



Order Urodela or Caudata. 



The tail persists in adult life ; the body is elongated ; the limbs are 

 weak when compared with those of Anura. 



(a) Forms like Proteus: — Two extant genera Proteus and Necturus, 

 both with persistent gills. Several species of Proteus inhabit the 

 water in the caves of Carinthia and Dalmatia in Austria. The 

 gills persist, there are two pairs of limbs. The eyes are de- 

 generate, the colours are pale, as we would expect in cave- 

 animals. Two species of Necturus (or Menobraruhus) occur 

 in North America, in rivers and lakes, such as those of the 

 Mississippi and Ohio basins. The pigment of the skin is well- 

 developed. 



(h) Forms like Siren : — Two extant genera, Siren and Pseudobranchus, 

 both North American, both with persistent gills, vrith only the 

 anterior limbs. 



(t) Forms like the newts and salamanders : — The North American 

 Amphiuma, with two pairs of rudimentary legs, with a slit per- 

 sisting in adult life as a remnant of the gilled state : the largest 

 living Amphibian Megalobatrachus or Cryptobranchus inaximus 

 of Japan and Tibet attains a length of three feet ; Amblystoma 

 and its gilled form the Axolotl ; Desmognathus fusca, the com- 

 mon water salamander of the United States, with eggs laid in a 

 wreath which one of the sexes twines round its body ; Sala- 

 mandra maculosa and S. atra, both European, both viviparous ; 

 the newts — Triton or Molge — of which Triton alpestris becomes 

 sexually mature while still larval. 



Order Gymnophiona or Apoda. 



Worm-like or snake-like forms, subterranean in habit ; without 

 limbs or girdles or tail ; with dermic scales concealed in the skin ; in 

 at least some forms, gills occur in early life ; the eyes are rudimentary ; 

 peculiar "tentacles" are connected with the orbit, and are perhaps 

 equivalent with " balancers," which occur in larval Urodela in front 

 of the first ^U-cleft. Cacilia in West Africa, Malabar, South America ; 

 Siphonops in Brazil and Mexico ; Epicrium in Ceylon ; Rhinatrema in 

 Cayenne ; Ccecilia compressicauda is viviparous. 



Order Labyrinthodontia or Stegocephala. 

 Extinct forms, occurring from Carboniferous to Triassic strata. 



