NEMATODA. 



163 



Parasitic in Man. 



Classification. 



At present the Nematodes are usually classified in families — Ascaridte, 

 AnguillulidsE, etc. With these we need not concern ourselves here, but 

 it is important to notice that the Gordiidce [e.g., Gordius aquaticus — the 

 horse-hair-worm) are very different from all the others. In the adult the 

 mouth is shut and the food-canal is partly degenerate. The adults live 

 freely in fresh-water ; the larvce occur in water insects, or in animals 

 (fish, frog, etc.) which eat these. 



* Von Linstow believes ^z.tjnlus gutUclatus is the intermediate host. 



