THE ANIMAL KINGDOM 89 



sible for much misery and shiftlessness among the 

 "poor whites" of the south, is an example. Other 

 common illustrations are: The harmless "Vinegar- 

 eel"; the pin worm of the alimentary canal; the 

 Trichinella, which imbeds itself in the muscles and 

 comes from infected and imperfectly cooked pork; 

 the Filaria, a blood parasite, etc. One thousand five 

 hundred living species are recognized. 



VI. Annelida.- -The segmented worms embrac- 

 ing the earthworm, the leeches and others. Some 

 forms burrow in the earth, others inhabit fresh water 

 (leeches), and salt water (Nereis). About 4000 

 living species are known. 



VII. Echinodermata.- -Marine animals with a 

 spiny skin or a calcareous test covering the soft parts. 

 The sea cucumbers, the starfishes, sea urchins, sea- 

 lillies, etc., belong to this group. They exhibit a 

 radial arrangement of parts. Locomotion is usually 

 by tube-feet connected with a characteristic water 

 vascular system. There are known approximately 

 3000 living and 2600 fossil forms. 



VIII. Arthropoda. Contains the largest number 

 of species of any phylum. Separated from all forms 

 of worms by possessing jointed appendages. The 

 phylum embraces several large classes as: (i) Crus- 



