256 



HOW DO WE CLASSIFY ANIMALS? 



Self-Testing Exercise 



Frogs are adapted to their environment by having (1) 



feet and a thin skin filled with (2) (3) by means 



of which they (4) oxygen. The frog breathes air by means of 



(5). The short (6) leads into a bag-like (7) 



which in turn opens into a much-coiled small (8). The 



heart is (9) chambered (10) are laid in water and 



develop into (11) which breathe by (12). These 



are replaced by (13). The tadpole feeds on (14) 



(15), but the adult frog eats (16). A relative of the 



frog is the (17). It lays its eggs in (18) in the 



water while those of the frog are found in (19). Toads are of 



much (20) in gardens where they (21) (22) 



insects. Other examples of (23) are newts and salamanders. 



PROBLEM VII. WHAT ARE CHARACTERISTICS OF THE 

 REPTILES? 



Turtles' adaptations for life. The turtles form a group, including 

 both sea and land animals, the latter called tortoises. The body 



is short and broad, 

 and is covered on 

 the upper and lower 

 sides by a bony 

 framework of plates 

 cemented to the true 

 bone underneath. 

 This shell is an adap- 

 tation for protection. 

 The long neck and 

 powerful, horny jaws 

 are factors in pro- 

 curing food. Turtles 

 have no teeth. Prey 

 is seized and held 

 by the jaws which 



Amer. Mus. of Natural Hist. 



How does the three-toed box turtle seem fitted to its 

 environment ? 



