CH-ETOGNATHA 



45 



This branch presents similarities to both Platyhelminthes 

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

 Classification. — 



Class. 

 I. Nemato'da. 

 II. Acan'thoceph'ala.' 

 III. Chaetog'natha.i 



Examples. 

 Trichina, Gordius. 

 Echinorhynchus. 

 Sagitta. 



'"The affinities of the Acanthocephala and Chsetognatha with the 

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

 i, p. 275. 



