CHyI^]TOGNATHA 45 



This })ranch presents similarities to both Platyhelminthes 

 and Annulata, but the relationship with either is not close. 

 Classification. — 



Class. Examples. 



I. Nemato'da. Trichina, Gordius. 



II. Acan'thoceph'ala.^ Echinorhynchus. 



III. Chaetog'natha.i Sagitta. 



i"The affinities of the Acanthocephala and Chaetognatha with the 

 Nematoda are somewhat doubtful," Parker and Haswell's "Zoology," vol. 

 i, p. 275. 



