THE TEREBELLA 99 



quarter of a second, and every tube will be corked 

 up by its tiny stopper, just as before. 



On the sides of its body the serpula has tufts 

 of little bristly hairs, just as the sabella has, 

 which allow it to move up and down its tube. 

 But in order to enable it to draw itself back as 

 quickly as possible in moments of danger, it has 

 a row of little hooked teeth on its back, by means 

 of which it can take a firm hold of the lining of 

 its burrow. I think you will be rather surprised 

 when I tell you how many of these teeth there 

 are in the row. Just fancy ! Each serpula has 

 between thirteen and fourteen thousand ! 



If you look at the oysters in a fishmonger's 

 shop, you may often see the tubes of these curious 

 worms fastened to the surface of the shells. 



PLATE XXXIII 

 THE TEREBELLA (i) 



This is another of the worms which live in 

 tubes. You can generally find its wonderful little 

 dwellings by hunting in the small puddles of sea- 

 water which are left on the sands when the tide 

 goes out. And you can always tell them from 

 those of the sabella and the serpula by the curious 

 little fringe round the entrance, which is made 

 of the tiniest grains of sand fastened together 



