XIV 

 REVIEW OF ANIMAL LIFE 



80. a. Classes of animals. The lowest animal which 

 we have studied is the Earthworm. Other well-known 

 worms are the Roundworm (Ascaris lumbricoides) and the 

 Tapeworm, both parasitic in the intestines of man. Com- 

 mon aquatic forms are the Leeches, generally called Blood- 

 suckers by children. 



All worms have a soft, elongated, and contractile body. 

 The body consists of rings or segments, and there is no 

 distinct head, thorax, or abdomen. Their body is not pro- 

 tected against the evaporation of moisture, and therefore 

 they can live in moist places only. When do earthworms 

 move about ? What becomes of them if they are acciden- 

 tally placed on dry boards or stones ? Can they creep over 

 dry ground ? 



You must remember that the maggots of flies, the grubs 

 of beetles, and the larvae of butterflies and moths, although 

 often called worms, are not worms. 



Articulates. These animals, to which the Crabs, Spiders, 

 and Insects belong, are much more highly organized than the 

 worms. The covering of their body is hard, and does not 

 restrict them to moist places. This hard armor consists of 

 several rings or segments, and does, therefore, not seriously 

 interfere with their motions. All of them show more or 

 less distinctly a head, a thorax, and an abdomen. They 

 have paired legs, and are provided with distinct organs of 

 sight and touch, and many have also organs of scent and 



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