PHYLUM PROTOZOA 81 



/) Water mites and water bears (Phylum Arthropoda): These are round to 

 oval flat animals with projecting legs. The water mites have six jointed legs 

 in the young state, eight in the adult. The water bear has eight short, non- 

 jointed legs provided with claws. 



g) Entomostraca (Phylum Arthropoda) : These common animals have 

 conspicuous jointed legs, and often large jointed antennae projecting from the 

 head. They swim in a jerky manner. One of the commonest types is Cyclops, 

 a small animal with a jointed body, single median eye, long swimming antennae, 

 and slender terminal spines; often also with two sacs full of eggs hanging to 

 the body. The water fleas have well-marked heads with large eyes, and powerful 

 swimming antennae, but the body is inclosed in a double shell, from which the 

 jointed legs may be protruded from time to time. 



This brief account of the microscopic animals commonly found in pond water 

 is merely intended to give the student an idea of the variety of form and structure 

 of aquatic life. Students who are interested will find more detailed accounts 

 of these animals in Stokes's Aquatic Microscopy, obtainable in the library. 



