30 STUDIES OF ANIMAL TYPES 



urchins. Note the spines on the body of the sea urchin. 

 Remove the spines and note the globular shell. Note the 

 five areas of the sea-urchin's shell. 



To what branch does the starfish belong? What other 

 animals belong to this branch? What is characteristic 

 of the skin of the starfish ? What kind of symmetry has 

 its body? All the members of this branch possess the 

 same body symmetry. Compare with the symmetry of the 

 body of the locust. Note that the starfish has a set of 

 tubes for the circulation of water. What is the nature of 

 the organs of locomotion? Most of the other members 

 of this branch possess the same kind of organs. Make a 

 summary of the digestive organs of this echinoderm. 



X. THE EARTHWORM 



Materials. Living and preserved earthworms, piece of glass, 

 tooth picks, dissecting instruments, wax-lined dissecting pan, pins, 

 magnifier. 



Directions. (Earthworms may be obtained after a warm rain 

 in spring by simply picking them from the ground. Failing in this, 

 they may be procured by digging in the soil. They will be found 

 more abundant in rich soils. Large specimens for dissection may be 

 had of dealers in such supplies.) 



A. STUDY OF A LIVING EARTHWORM. Place a live worm 

 on a rough surface, for instance, the top of a table or sheet 

 of paper. Watch its movements. Does it move with the 

 same end always foremost? Can it move backward? 

 Does it hold the same side of the body uppermost ? Turn 

 it over and note the results. Note the lengthening and 

 shortening of the body when it moves. Has the earth- 

 worm any visible locomotor appendages ? 



