CYCLOPS. 37 



in this way, and with a lens make out their shape 

 and arrangement. 

 9. Under the thorax of the female there is a series 

 of thin membranes attached near the bases of the 

 legs. These are the egg-covers. The eggs, after 

 being expelled from the body, undergo their develop- 

 ment in the space under the thorax enclosed by these 

 egg-covers. Look for specimens carrying eggs in this 

 manner. 

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

 In what respects 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. 



See Chapter XVIII of Morse's "First Book of Zoology." 



CYCLOPS. 



Along the sides of aquaria, and sometimes in drink- 

 ing-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 



