CLASSIFICATION 



25 



CLASSIFICATION 



For the sake of convenience in discussing the character- 

 istics of animals the entire kingdom is divided into sub- 

 kingdoms, classes, orders, families, and species, as given in 

 the following outline. It is not intended that this incom- 

 plete table of classification should be memorized, but 

 rather that the pupils should become familiar with it as 

 indicated in the practical questions by constant reference 

 to it throughout the term. 



SUBKINGDOM I. PnoTOz5'A (first animals) : Single-celled 

 aquatic animals of microscopic size. Ameba 

 and Paramcecium (Figs. 211, 209). 



SUBKINGDOM II. PORIF'ERA (pore bearers): Sponges. 



SUBKINGDOM III. COSLENTERA'TA (hollow within): Aquatic 

 mostly marine animals having but one inter- 

 nal cavity. Jellyfish, coral builders, and 

 hydroids (Figs. 203, 199). 



SUBKINGDOM IV. PLA"TYHELMIN'THES (flatworms) : Worms with 

 flattened bodies and no cavity surrounding 

 the alimentary canal. Tapeworms and 

 liver fluke (Fig. 184). 



SUBKINGDOM V. NEMATHELMIN'THES (thread worms): Round 

 worms with no external evidence of seg- 

 ments. Horsehair worm and vinegar eel 

 (Fig. 183). 



SUBKINGDOM VI. TROCHELMIN'THES (wheel worms): Minute 

 aquatic worms with cilia about the mouth. 

 Rotifer. 



SUBKINGDOM VII. MOLLUSCOI'DA (like a mollusk) : Aquatic 

 worms usually living in colonies. Sea mats. 



SUBKINGDOM VIII. ECHINODER'MATA (spiny skinned) : Marine 

 radiate forms often covered with spines. 

 Starfish and sea urchin (Figs. 187, 190). 



