386 



MANUAL OF ZOOLOGY. 



Mexican lakes, and attains a length of about a foot or fourteen 

 inches. It possesses both pairs of limbs, the anterior pair 



having four toes and the hinder 

 pair five toes. As ordinarily 

 known in its native country, 

 the Axolotl is certainly perenni- 

 branchiate, and they breed in 

 this condition freely. There 

 is no doubt, however, that in- 

 dividual specimens may lose 

 their gills, without thereby suf- 

 fering any apparent change, 

 except it be one of colour. 

 The Axolotl, therefore, is in 

 the singular position of being 

 sometimes " caducibranchiate," 

 whilst it is ordinarily " perenni- 

 branchiate." Nearly allied to 

 the Axolotl is the Menobran- 

 chus of North America, in 

 which the branchiae are per- 

 sistent. Amphiuma and Meno- 

 poma, as already remarked, 

 differ from the forms just men- 

 tioned in losing the gills when 

 adult, but in retaining the ex- 

 ternal branchial 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. 



In the second section of the 

 Urodela, comprising those forms 



Fig. 148. The Axolotl (Siredon pisci- 



forme) after Tegetmeier. The ordinary i_- i .1 MI 



form, with persistent branchiae. HI which the gills are CaduCOUS, 



and both pairs of limbs are 



always present, are the Water-salamanders or Tritons, and the 

 Land-salamanders. The Tritons 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. 149) are distinguished 

 from the terrestrial forms by being furnished with a compressed 



