POLYPS 29 



of defunct members into one massive block, which otters 

 considerable resistance to wind and waves. It likewise 

 serves as a haven for the enormous numbers of molluscs, 

 worms, sponges, etc., that habitually tunnel into it for 

 shelter. Reef Corals can only form in comparatively 

 shallow water, light and air being essential to their makers' 

 well-being. Two such reefs are world-famous — the Great 

 Barrier Reef of Australia, extending for 1,315 miles from 

 New Guinea southwards along the entire coast of Queens- 

 land, and the notorious Cocos Atoll, never for long out 

 of the news as a home of treasure trove. 



Coral reefs are divided into three well-defined groups. 

 (1) Fringing reefs, which occur round continents or 

 islands ; (2) Barrier reefs, that form much farther out from 

 land masses, with a deeper channel between them and the 

 land than is permitted by the former type ; and (3) Atolls, 

 which are roughly circular in formation, often situated 

 far from land, with much of their boundaries raised above 

 sea level. Within the atoll reef is a still lagoon never 

 exceeding 50 fathoms in depth. The shelter afforded 

 transpires to make these reefs the retreat of innumerable 

 sea animals of every kind and constitute a wealth of life 

 that would appear to be literally unlimited despite its 

 wholesale exploitation and despoliation at the hands of 

 man. 



Sea Anemones are practically world-wide in distribution, 

 and their variety of size and coloration is so great that it 

 can here be only touched upon. Most Anemones remain 

 fixed to some stable object throughout life, though many 

 can slowly glide from one spot to another by means of 

 the flattened lower portions of the body. The crown 



