THE PHYLA ASCHELMtNTHES AND NEMERTEA 235 



6. Compare the excretory systems of rotifers and roundworms. 



7. Describe the life cycle of Ascaris. 



Supplementary Reading 



All of the pseudocoelomates are included in The Itn/ertebrates, volume III, by 

 L. Hyman, with many descriptions and life cycles. Helminthology, the study of parasitic 

 worms (trematodes, cestodes, acanthocephalans and nematodes), is the subject of several 

 texts. The nemerteans are found in volume II of the same series by Hyman. 



