THE SAND SCREW 89 



PLATE XXIX 



THE SAND SCREW (2 and 2 A) 



If you follow the tide as it goes out on a still 

 day, you will notice that it leaves the sand quite 

 smooth behind it. But if you come to the same 

 spot about half-an-hour later, you will often 

 find that it is marked by numbers of winding 

 tracks, which look just as if they had been made 

 by worms. These, however, are the work of the 

 Sand Screw, a curious little creature which in 

 many ways is very much like a sandhopper. But 

 instead of sinking its burrows almost straight 

 downwards into the sand, as sandhoppers do, it 

 drives them along almost as a mole does, just 

 below the surface. 



If you stand quite still for a few minutes near 

 the water's edge, when the tide is going out, 

 you may sometimes see this odd little creature 

 at work ; for as it pushes its way along it raises 

 the sand into a kind of low tunnel, which gener- 

 ally falls in behind it, and so forms a groove. And 

 if you suddenly turn over the sand in front of the 

 tunnel you will find the little animal which was 

 making it, and will see at once why it is called 

 the " sand screw." For instead of skipping about 

 like a sandhopper, it will lie on one side and 



