250 VERTEBRATE ANIMALS. 
ramified processes on each side of the head; and the tail is 
compressed, and fringed by a fin which is prolonged on 
Fig. 134.—The Axotlotl (Szvedon pisci- 
JSorme)—after Tegetmeier. The ordinary 
form, with persistent branchia. 
the back between the 
shoulders. In a state of 
nature, the Axolotl is cer- 
tainly perennibranchiate, 
and it breeds freely in this 
condition. It has been 
shown, however, by Prof. 
Marsh, of New Haven, that 
some species, when kept in 
confinement, lose their gills, 
and undergo certain other 
changes, becoming  ulti- 
mately converted into a 
Salamandroid, apparently 
belonging to the genus 
Amblystoma. 
The Proteus is an extra- 
ordinary Amphibian which 
is found inhabiting the 
waters 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 through- 
out 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 
extremely small, the animal 
spending its existence in 
darkness ; and swimming is 
effected mainly by means of 
the tail. The Szrex or Mud-eel 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 branchiz 
