THE DIFFERENT TYPES OF ARTHROPODA 285 



Exercise 14. A comparison of tJie thoracic appendages. Appendages 6, 7, 

 and 8 of the thorax are known as the first, second, and third maxillipeds, and 

 the appendages from 9-13 are the walking appendages. Write out a comparison 

 of the thoracic appendages, noting the number, segmentation, etc. 



Exercise 15. A comparative study of the abdomens of the crayfish and 

 locust. Appendages 14-20 of the crayfish are known as the swimmerets. 

 Compare these with the more anterior appendages of the crayfish. Also write 

 out a careful comparison of the segmentation of the abdomens of the crayfish 

 and locust. 



Exercise 16. Make a drawing of the side view of the crayfish, naming the 

 different appendages and divisions of the body. 



Exercise 17. Make drawings of appendages 2, 10, and 16. 



Exercise 18. Comparison of the locust and sow-bug. Write out a careful 

 comparison of these two forms, noting : 



1. The nature of the body covering. 



2. The general divisions and segmentation of the body. 



3. The nature of the appendages. 



4. The number and position of the appendages. 



Exercise 19. Make a drawing of the ventral view of the sow-bug, showing 

 the number, position, and arrangement of the appendages. 



SECTION VII. COMPARISON OF INSECTS AND MYRIAPODA 

 (TYPES, LOCUST AND CENTIPEDE) 



Material. Centipedes are flattened, wormlike animals livingunder logs, stones, 

 and other damp localities. They are quite common in most places, and may be 

 collected and preserved in 75 per cent alcohol. Large specimens may usually 

 be supplied by most of the natural-history supply houses. 



Exercise 20. Write out a detailed comparison of a centipede and locust, noting 

 the following points : 



1 . The general divisions of the body. 



2. The nature of body covering. 



3. The segmentation of the body. 



4. The eyes and antennae. 



5. The mouth-parts. 



6. The legs, number of their segments, etc. 

 Exercise 21. Make a drawing of the dorsal view of the head. 

 Exercise 22. Make a drawing of a ventral view of the head. 



