PSEUDOCOELOMATE AND MINOR EUCOELOMATE PHYLA 



female in a sort of brood chamber. After a brief period of free existence, the 

 larva settles upon the substrate, develops a stalk for attachment, and under- 

 goes a metamorphosis into the adult condition. 



THE PHYLUM CHAETOGNATHA 



The phylum Chaetognatha consists of small marine animals, called "arrow 

 worms." Their precise relationship to other phyla is doubtful, but their 



- Bristles 



Ovary, 



Fig. 12.16. .Anatomy of a typical chaetognath, 

 Sagttta hexaplera, ventral aspect. (Redrawn, after 

 O. Hertwi?, from C. Schneider, 1902, Lehrbuch der 

 veroleichenden Hutologie der Tiere.) 



Oviduct- 



Ganglion 



.Gut 



Anus 



Testis 



365 



