CLASSIFICATION OF ANIMALS 



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VI. Annula'ta (Lat. annulus, a ring), or Coelhelmin'thes. — Segmented 

 worms; long, jointed creatures composed of body rings or segments. The 



digestive tract is a tube within a tubelike body, 

 pendages. There are about 4000 known species. 



They have no jointed ap- 



There are two classes : 



Class I. Choetop'oda. Many bristles along the sides of the body. Examples are the earth- 

 worm or sandworm. 



Class II. Hirudin' ea. Without bristles and having suckers at both ends of the body. Exam- 

 ples are the leeches or bloodsuckers. 



VII. Echinoderma'ta. — These are spiny-skinned animals which live in 

 salt water. They are more complicated in structure than the worms and may 

 be known by the spines in their skin. They show radial symmetry. There 

 are about 4500 named species. 



Starfish Brittle star Sea urchin Sea cucumber 



Echinodermata. 



Sea lily 



Classification is as follows : 

 Class I. Asteroi'dea, or starfishes. 



Class II. Ophiuroi'dea, the brittle stars or snake stars. 

 Class III. Echinoi'dea, or sea urchins. 

 Class IV. Holothuroi'dea, including the sea cucvimbera. 

 Class V. Crinoi'dea, or stonelike, deep-sea forms, now almost extinct ; sea lilies and sea 



feathers. 



VIII. Arthrop'oda (Gr. arthros, joint; pous, foot). — Animals which are 

 jointed, with limy or chitinous exoskeletons and jointed appendages. They 

 live in water, or on land, or in the air, or in all three elements. Most of them 

 undergo a metamorphosis. There are about 500,000 known species, more than 

 all the rest of the animal kingdom put together. 



Crab 



Centipede 



Arthropoda. 



Insect 



Spider 



