STUDY IV. VERMES. Worms. 



Central ideas : Division of labor carried still farther. 

 The bi-lateral plan of structure. 



1. A FLANARIAN 'WORM. 



1. What is its habitat ? (Dem.) 



2. Distinguish the blunt "head end" (anterior) from 



the opposite pointed end (posterior). 



3. Distinguish the upper surface (dorsal) from the 



lower surface (ventral). 

 How can you always locate the right and the left 

 side of an animal when you know its anterior end 

 and its dorsal surface ? 



4. See two tiny spots (" eye "-spots) in the antero- 



dorsal region. These indicate the locality of the 

 nerve centers. 

 Why has the animal become most sensitive at the 

 anterior end ? 



5. Identify a short tube lying lengthwise against the 



postero-ventral region of the body. (The mouth 

 is at the end of this tube.) 



6. Identify the large, branching, brownish alimentary 



canal. 

 What is the special advantage of this type of an 

 alimentary canal ? 



7. How does this alimentary canal resemble in plan the 



digestive cavity of the Hydra ? 

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