ADAPTATION TO SURROUNDINGS 8i 



8. How many thoracic appendages has it, if any ? 



9. What methods of locomotion does it use ? 



Summary. 



1. Does this animal seem to be adapted to life on land 

 or in water, or both ? Give your reasons for your opinion. 



2. What characteristics are common to all the Crustacea 

 you have studied ? 



3. REVIEW AND LIBRARY WORK ON CRUSTACEA 



1. What are arthropods ? 



2. Give the classes of arthropods with an example of 

 each. 



3. What are the distinguishing characteristics of the 

 class Crustacea ? 



4. In what respects are most of the appendages of the 

 crayfish homologous, i.e. alike in the plan of structure ? 

 Which do you consider the simplest, and why do you ? 

 Which do you consider the most specialized, and why ? 



5. Which somite of the crayfish is without appendages ? 

 How many somites are there in a crayfish's body, if each 

 somite bears only one pair of appendages, as many scien- 

 tists believe ? How many of these are in the head ; tho- 

 rax ; abdomen ? 



6. Compare the nervous system of the crayfish with that 

 of the earthworm as regards efficiency. Upon what do you 

 base your answer .? 



7. Name two points in which earthworms and crayfishes 

 are alike. Name three in which they differ. 



8. How are crayfishes caught for market .' Where do 

 those sold in Chicago usually come from ? How are they 

 shipped ? 



9. Compare the young forms of a crayfish and a crab. 



