GENERAL CHARACTERS 163 



the ribs are very long and pointed and frequently perforate the 

 skin. 



The sub-family Amblystomatinae, which includes the cele- 

 brated axolotl, consists of seven genera distributed through 

 North America, Mexico, and Northern Asia from the Ural 

 Mountains to Kamtchatka, Japan, China, and Siam. The 

 largest genus is Ambly 'stoma, of which sixteen species are North 

 American and one occurs in Siam ; the Mexican axolotl is 

 the sexually mature larval form of A. tigrinum, a species 

 which occurs from New York to California and Central 

 Mexico. 



Fam. AmphiumiD/E. — -Gill-processes are absent in the adult, 

 but except in the huge Japanese Giant Salamander, Cryptobran- 

 chus japonicus, one pair of gill-clefts persists, namely the last 

 pair, or occasionally only the one of the left side. Maxillary 

 bones are present, teeth in both jaws and in transverse rows on 

 the vomers. The vertebrae are amphiccelous — concave at each 

 end. Both pairs of limbs are present but the eyes are small 

 and without eyelids. 



There are only three species in this family. The three- 

 toed salamander, Amphiuma means or tridactyla, is about three 

 feet long and lives in swamps and the ditches of rice grounds 

 in the south-eastern States of North America. (Plate XIV., B.) 

 The fore and hind limbs are small, and far apart, ending in three 

 small toes ; the tail is short. The small gill-cleft on each side is 

 just in front of the fore limbs. The North American " Hell- 

 bender " Cryptobrancluis or Menopoma alleghaniensis, which lives 

 in the rivers of the mountainous regions of the eastern States of 

 North America, is shorter than Amphiuma, not exceeding 

 eighteen inches in length, but is much stouter and broader with 

 longer tail, more similar to an ordinary newt ; the limbs are also 

 more developed with four toes on the fore-foot, five on the hind. 

 The tail is fringed with a fin-membrane. The skin is very 

 glandular and projects into a thick undulating ridge along the 

 sides of the body. Cryptobranchus japonicus, the giant sala- 

 mander of Japan, lives in that country and in China in 

 mountain streams, hiding in holes or burrows ; it reaches the 

 enormous length of four or five feet. The gill-slits are all closed. 

 It is apparently very long-lived since in captivity a specimen 

 lived for fifty-two years. 



