38 PRACTICAL ZOOLOGY. 



on 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. i 



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 order Entomostraca (water-fleas). 

 Read "Anatomy and Metamorphosis of Cyclops," in 

 Brooks' " Handbook of Invertebrate Zoology." 



OTHER CRUSTACEA. 



The lobster is almost exactly like a crayfish, only larger. 

 If a lobster can be obtained, carefully compare it with the 

 crayfish. Shrimps are also very much like crayfishes. 

 Crabs have wide bodies and very short abdomens, folded 

 closely under the body. The structure of crabs, both 

 internal and external, is essentially the same as that of 

 crayfishes. The crab which is so much used for food has 

 the hinder pair of legs developed as paddles for swimming, 

 the outer segments being flattened. This crab swims 

 sideways. Just after moulting it is known as the " soft- 

 shell crab." 



The little oyster crab, which often comes to us with our 

 oysters, is not a young crab, but is the female of one of 

 the smaller species of crabs. 



