A'RETEBRATE ANIMALS. 



stoma. Moreover, in one species (viz., Amhlystoma mavortium), this 

 change is known to occur in a state of nature ; the larva being an 

 Axolotl, with gills, and capable of breeding, but ultimately changing 

 to a gill-less Salamander. 



The Proteus is an extraordinary Amphibian which is found in- 

 habiting the water's of caves in Illyria and Dalmatia. It attains a 

 length of about a foot, and is of a pale flesh-colour or nearly white. 

 The gills, which are retained throughout life, are of a bright scarlet. 

 Both pairs of limbs are developed, but they are only short and 

 weak, the fore-limbs having three toes each, and the hind-limbs only 

 two. The eyes are rudimentary, the animal spending its existence 

 in darkness ; and swimming is effected mainly by means of the tail. 

 Allied to Proteus is the Mud-puppy {Menobrmichus, fig. 181, C) of 



Fig. 181.— Tailed Amphibians. A, Siren hiceriina; B, Amphiuma^ showing the fonr 

 minute limbs; C, Mcjiohrancliv^ maculatvs. (After Mivart.) 



North America, which is from six inches to a foot in length. The 

 Siren or Mud-eel (fig. 181, A) is a large lizard-like Amphibian, 

 which is found abundantly in the swamps of South Carolina, and 

 attains the great length of three feet. The external branchise are 

 retained throughout life, and they are the main organs of respira- 

 tion. The fore-limbs are present, but the hinder pair of limbs is 

 never developed. Another form, which occurs in the Southern 

 United States, is the (Jongo-snake {Ampliimna). This has a snake- 

 like body, with rudimentary two-toed limbs (fig. 181, B), and though 

 the gill-slits remain on the side of the neck, it has no gills. 



