THE SORTING OF PLANTS AND ANIMALS 



8i 



family, mint family, morning-glory family, plantain family, 

 madders, honeysuckles, composites — daisy, aster, sunflower, 

 goldenrod, etc.) 



65. The main groups of animals. The chief groups of animals 

 are indicated in the following outline : 



BRANCH I — PROTOZOA. The simplest animals ; body of one cell. {Ex- 

 amples. Ameba, Paramecium, Vorticella, Plasmodium of malaria.) 









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V::V^m::^ 





NJ'S 



11 



Fig. 45. Eyespots in starfish 



The eyespot at the end of each ray is con- 

 nected with the nervous system of the ani- 

 mal and is more sensitive to light than 

 the rest of the body surface 



Fig. 46. Sea urchin 



Animals of this branch deposit large 



quantities of lime in their skin, and 



produce knobs and spines that form a 



protective armor 



BR.\NCH II— PORIFERA (''pore-bearing" animals). This includes 

 all the sponges. 



BRANCH III — CCELENTERATA. Radially symmetrical animals hav- 

 ing a single cavity in the body : all aquatic, mostly marine. 

 Class i — Hydrozoa. {Examples. Fresh-water hydra, certain small 



jellyfish.) 

 Class 2 — Actixozoa. (Examples. Most anemones, most corals.) 

 Class 3 — Scyphozoa. {Examples. Most of larger jellyfish.) 



BRANCH R' — FLATWORMS (Platyhelminthes). {Examples. Tape- 

 worm, liver fluke, planarians.) 



BRANCH V— ROUNDWORMS (Nemathelminthes). {Examples. Hook- 

 worm, trichina, thorn-headed worm.) Many of these animals are 

 dangerous parasites on man or on domestic animals. 



