204 VERTEBRATA 



from Arkansas to North Carolina. Its limbs, two or three- 

 toed and less than an inch long, illustrate the effect of dis- 



FIG. 235. The mud puppy or water dog, showing the gills projecting from either 

 side of the neck. Photograph one third natural size. 



use of an organ. The mud eel (Siren lacertina) of South 

 Carolina is similar to the congo snake in habits and form, 

 but has no poste- 

 rior limbs and ex- 

 hibits external 

 gilts like the mud 

 puppy 



Anura : tailless 

 * Amphibia 



This order in- 

 cludes the frogs 

 and toads which 

 are found in nearly 

 all parts of the 



FIG. 236. Photograph of fbo congo snake one third 

 WOrld. In the natural sizfc 



