ORDERS OF AMPHIBIA. 



437 



to the Axolotl is the Mbnobranchus of North America, in 

 which the branchiae are persistent. Amphiuma and Menopoma, 

 as already remarked, differ from the form just mentioned in 

 losing the gills when adult, but in retaining the external bran- 

 chial apertures on the side of the neck. The former is 

 exclusively North American, whilst the latter is represented 

 by different but nearly-related species in both North America 

 and Java. Both possess the 

 normal two pairs of limbs. The 

 Javanese species (Menopoma 

 maxima) has the gill-slit closed 

 in the adult. It is about three 

 feet long, and is the nearest 

 living relative of the extinct 

 Andrias. 



In the second section of the 

 Urodela, comprising those forms 

 in which the gills are caducous, 

 and both pairs of limbs are 

 always present, are the Water- 

 salamanders or Tritons, and the 

 Land -salamanders. The Tri- 

 tons are the only examples of 

 the aquatic Salamanders which 

 occur in Britain, and every one, 

 probably, is acquainted with 

 the common Newt. 



The Water-salamanders or 

 Newts (fig. 1 88) are distin- 

 guished from the terrestrial 

 forms by being furnished with 

 a compressed fish-like tail, and 

 by being strictly oviparous. 

 The larvae are tadpole-like, 

 with external branchiae, which 

 they retain till about the third 

 month. The adult is destitute 

 of gills, and breathes by lungs 

 alone, but the larval tail is re- 

 tained throughout the life of 

 the animal. The tongue is 

 small, free, and pointed be- 

 hind, and there are two rows 

 of palatine teeth. The fore-feet are four-toed, the hind -feet 

 five-toed : and the males have a crest on the back and tail. 



Fig. 187. The Axolotl (Siredon pisci- 

 Jorme] after Tegetmeier. The ordi- 

 nary form, with persistent branchi se. 



