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TEXTBOOK OF ZOOLOGY 



in the parenchyma; in the adult female the two lateral spaces are 

 lined with peritoneum. The nervous system is composed of a mid- 

 ventral cord with a nerve ring at the anterior end. There are 

 rudimentary eyespots and scattered sensory cells over the body. 





Fig. 89. — Structure of Acanthocrphala. Internal structure of the genital organs 

 of a young female nematode, Neoechinorhynchus emydis. (From Van Cleave, 

 Invertebrate Zoology^ first edition, second impression, published by McGraw-Hill 

 Book Company, Inc.) 



Sexually the group is dioecious with the gonads opening into the 

 posterior end of the digestive tract. Fertilization takes place within 

 the body of the female. Gordius aquaticus and Paragordius varius 

 are the common examples of the group. 



