I 88 COLLEGE ZOOLOGY 



the dorsal surface near the anterior end. They live in the sand 

 or bore into coral reck, and are capable of slow, creeping loco- 

 motion. The anterior part of the body can be drawn into the 

 larger posterior portion, and is therefore called the introvert. 

 Tentacles (Te) are usually present at the anterior end. 



(3) The Priapuloidea (Fig. 130) are unsegmented, with an 

 anterior mouth (a) surrounded by chitinous teeth, and a posterior 

 anus. They live in the mud or sand with the anterior end 

 projecting from the surface. 



