268 



A COURSE ON ZOOLOGY. 



FIG. 209. 



is aquatic in its habits ; its food consists of worms, crus- 

 taceans, and water insects. 



The echidna is sometimes called spiny ant-eater, for 



it lives mainly on ants. 

 It has a long-pointed 

 muzzle, and the fur 

 of the back is inter- 

 spersed with strong 

 spines about two 

 inches long. It can 

 burrow very rapidly 

 in soft earth. There 

 are several varieties 

 ECHIDNA ACULEATA. o f this creature found 



in the rocky and 



mountainous regions of New Guinea, Tasmania, and 

 Australia. 



CHAPTER XXIX. 

 Birds. 



THE classification of birds does not rest on a satis- 

 factory basis like that of mammals. All living birds are 

 divided into two subclasses, the ratitae, or flat-breasted 

 (raft-breasted) birds, which is small in 'number, and the 

 earinatae, or keel-breasted birds, which includes all the 

 others. 



RATITAE. 



The wings of these birds are short or rudimentary, 

 and are not adapted for flying ; the breastbone is flat, 



