284 



ZOOLOGY 



adult life they spend most of their time on the trunks of trees, 

 where they receive immunity from attack because of their color 

 markings. The feet of the tree toad are modified for climbing by 

 having little disks on the ends of the toes, by means of which it is 



able to cling to verti- 

 cal surfaces. 



Another amphibian 

 is the salamander, a 

 smooth-skinned, four- 

 limbed animal, often 

 incorrectly called a 

 lizard. These animals 

 pass their early life in 

 the water, later com- 

 ing out on land. After 

 passing through the stages of the segmenting egg, with few excep- 

 tions they breathe by means of external gills; later they may 

 develop lungs. A few never have lungs, but breathe through the 

 moist skin. 



Spotted salamander. From photograph loaned by the 

 American Museum of Natural History. 



Newt. From photograph loaned by the American Museum of Natural History. 



Still other amphibians are the mud puppies, sirens or mud eels, 

 and the axolotl. All of the above animals differ from the reptiles 

 in having a smooth skin with no scales, and in passing the early 

 stage of their existence in the water. 



