Amphibia. 



191 



The Mud Puppy. The mud puppy, or water dog, is a 

 little higher than the siren, having two pairs of legs. It 

 also has persistent external gills. It is found in the streams 



FIG. 121. NECTURUS; MUD PUPPY (NORTH); WATER DOG (SOUTH). 



Gills retained thruout life. 



of the Mississippi Valley and in the lakes of central New 

 York. It sometimes 'attains a length of two feet. 



FIG. 122. SPOTTED SALAMANDER. 



The Salamanders. The salamanders are still a step 

 higher. They have gills in the earlier stage, but shed them 

 when adult. They retain the tail, and, in swimming, fold 



