THE PACIFIC OCEAN. 271 



T)are spot on the windward edge at the lowest ebb of 

 spring tide. 



Captain Basil Hall has recorded some pleasing 

 observations on this singular formation, in his voyage 

 to Loo-Choo. lie says — 



" The examination of a coral reef during the dif- 

 ferent stages of one tide, is particularly interesting. 

 When the sea has left it for some time, it becomes 

 dry, and appears to be a compact rock, exceedingly 

 hard and rugged ; but no sooner does the tide rise 

 again, and the waves begin to wash over it, than 

 millions of coral worms protrude themselves from 

 holes on the surface, which were before quite in- 

 visible. These animals are of a great variety of 

 ghapes and sizes, and in such prodigious numbers 

 that in a short time the whole surface of the rock 

 appears to be alive and in motion. The most com- 

 mon of the worms at Loo-Choo was in the form of a 

 star, with arms from four to six inches long, which 

 it moved about with a rapid motion in all directions, 

 probably in search of food. Others were so sluggish 

 that thpy were often mistaken for pieces of the rock ; 

 these were generally of a dark colour, and from four 

 to five inches long, and two or three round. When 

 the rock was broken from a spot near the level of 

 high-water, it was found to be a hard, solid stone ; 

 but if any part of it were detached at a level to 

 which the tide reached every day, it was discovered 

 to be full of worms, all of different lengths and 

 colours, some being as fine as a thread, and several 

 feet long, generally of a very bright yellow, and 

 sometimes of a blue colour; while others resembled 



