SHALLOW-WATER FAUNA. 35 



found on an acre of sand where conditions are 

 favourable for these Worms, and that they would 

 weigh together nearly 2000 tons. This would 

 mean that the whole mass of the sand would 

 pass through the bodies of Lug-worms on an 

 average of once in every twenty-two months. 



But the Lug-worm is only one of 

 the many forms of life that burrow 

 in the sand. A very large number 

 of bivalve Molluscs live with the 

 greater part of their bodies per- 

 petually buried. Their organisation 

 is such that their food and the water 

 that is used for respiration can be 

 brought to them by a tubular pro- 

 longation of the body called the 

 siphon. Some of these animals live 

 much deeper down than others, and 

 while some have but feeble powers 

 of moving either up or down in their 

 burrows, others can penetrate to 

 great depths with extraordinary 

 rapidity. 



The shell of a Lamellibranch, 

 called the Kazor-shell (Soleri), is not 

 an uncommon object of the sea-shore a w n s d int0 an n d 

 where stretches of sand occur. When a b o v e the 

 the animal is alive it has the power of Slphons - 

 burrowing down so quickly that it is practically 

 impossible for one man to capture a specimen by 

 digging, when it is thoroughly alarmed. Occasion- 

 ally, however, the sea itself, when lashetj. into fury 

 by a storm, is a better digger than the Solen is a 

 burrower ; and after a heavy storm in the Isle 



