46 Practical Zoology. 



egg covers. The eggs, after being expelled from the body, 

 undergo their development in the space under the thorax in- 

 closed by these egg-covers. Look for specimens carrying *ggs in 

 this manner. 



10. In what respect are the sow bug and crayfish alike? In 

 what respect do they differ from each other? 



The crayfish and sow bug both belong to the Crustacea. The 

 class Crustacea is divided into several orders. The order to 

 which the crayfish belongs is the Decapoda, or ten-footed ; the 

 sow bug belongs to the order Tetradecapoda, or fourteen-footed. 



CYCLOPS. 



Along the sides of aquaria, and sometimes in drinking water, 

 there may be seen minute white animals swimming with a jerky 

 motion. Cyclops has a pear-shaped body, and is just large 

 enough to be seen readily with the naked eye. The females carry 

 two egg masses attached to the sides of the abdomen. With a 

 lens, watch these animals through the side of the aquarium. 

 Place a female cyclops with a few drops of water in a watch 

 crystal, or a piece of glass. Examine under a three-legged lens, 

 or under a low power of the microscope. 



1. The foremost division of the body is the carapace. 

 How many segments has the thorax? 



2. The egg sacs are attached to the first ring of the abdomen. 



3. The eye ; note its color, position, shape, and parts. 



4. The antennae and other appendages. 



5. How does cyclops swim? 



Make a careful drawing of cyclops as seen from above. Cyclops 

 belongs to the subclass Entomostraca (water fleas) . 



