AMPHIBIA 



193 



at first grayish and later jet-black. The eyes are rudimentary and 

 completely hidden beneath the opaque skin. It has been suggested 

 that the conditions for development are such as to inhibit certain 



FIG. 113. Group of perennibranchiate urodeles. A, Necturus maculatus; B, 

 Proteus anguineus; C, Typhlomolge rathbuni; D, Siren lacertina. (Redrawn after 

 Lydekker and others.) 



structures such as the eyes and pigment from developing. Possibly 

 this might also be tied up with the permanently larval condition. 

 They require very little nourishment, probably being accustomed to 

 only a minimum amount in their natural habitat. 



