PHYLUM NEMATHELMINTHES 



177 



Class Gordiacea (gor di a'she a, a knot). — Superficially these ani- 

 mals resemble the nematodes, but the fundamental structure is quite 

 different, and therefore, it is likely proper to give them the rank of 

 a class. They are free-living as adults but as larvae are parasitic 

 on May flies and other insects. They leave this host and take 

 up abode in a terrestrial form like that of grasshoppers or beetles. 

 After complete development the adult "hair snakes'' escape into 



Fig. 88. — Hair snake, Gordius, an aquatic roundworm. 



the water of some stream, puddle, or watering trough. These 

 females again lay eggs in the water in long strings. In the adult 

 worm the intestine is a straight tube, often without a mouth, but 

 opening at the posterior end by an anus. Some have no intestine 

 at all. The outer surface of the body is covered by a cuticle. The 

 body is cylindrical and without lateral lines, excretory organs, or 

 circulatory system. There are four longitudinal spaces or sinuses 



