THE CRAYFISH 



103 



by great physical effort. Accidents frequently occur during 

 molting in which the animal loses one or more appendages, 

 but as they are quickly replaced, it soon recovers its complete 

 form. The hard parts of the stomach are shed at each 

 period of molting. Why? Why does the crayfish molt? 

 What is the condition of the animal when molting has 

 been completed? Read the complete life history of the 

 crayfish. 



Habits. — What food do crayfish relish? How can 

 they choose their food ? Can they live out of water ? How 

 do they breathe out of water? How do they spend the 

 winter? How do they defend themselves? Do they fight 

 often? Are they courageous when attacked? How do 

 they show it? If they lose appendages how do they repro- 

 duce them ? 



Classification. — Summarize the principal types you 

 have studied, by a comparison, including similarities and 

 differences, of the grasshopper, spider, centipede and cray- 

 fish. Tabulate the summary as before. 



SIMILARITIES. 



DIFFERENCES. 



