72 The Under-Water World 



often gorgeously coloured, the tube with 

 the gill plumes fully extended resembling 

 some long-stalked delicate flower. 



The resplendent Peacock Tube Worm 

 (Sabella pavonina) which protrudes long 

 green and purple gill-filaments, erects 

 stout sandy turrets of such strength and 

 profusion as to form wave-resisting reefs 

 on certain parts of our south-west coast. 



The Leeches are familiar members of 

 the annelid tribe, one species being still 

 used in medicine, for which purpose it is 

 extensively bred on the Continent. They 

 have powerful basal suckers, and circular 

 mouths rimmed with saw-edged teeth, 

 by means of which they attach them- 

 selves to their prey. Only one species 

 is marine. 



The Nemertines or Ribbon Worms 

 have long, unsegmented ribbon-like 

 bodies capable of great expansion. The 

 group's most striking characteristic is 

 the proboscis, which is retracted into a 



