456 NATURAL SCIENCE. June. 



supplies of sea-water. Again, nearly all masses of coral grow more 

 or less like a fairy ring — living and expanding at the edges, decaying, 

 getting ground down into debris, or dissolved by the sea-water at the 

 centre. The action of various forms of life living on the coral also 

 assists this process. Shell-fish grow on the coral and become 

 embedded in it, and round the intruding giant clams embedded in the 

 coral waves a region of decay is usually present. 



A valuable part of the book is occupied by an account of the 

 actual corals and coral animals. To those who are familiar only with 

 the bleached and dried specimens of museums and cottage windows, 

 the account of the marvellous colours of the living corals will be a 

 revelation. The soft tissues of the polyps have all the colours of the 

 rainbow — sometimes blended in soft and delicate shades, often in the 

 most startling and violent mixtures. The other reef-living animals — 

 animals like the star-fishes, sea-urchins, sea-cucumbers, Crustacea, 

 and shell-fish — which contribute to the lime-supply of the reef, and 

 the various fishes living in the shallows, all are similarly radiantly 

 attired. 



Foraminifera are present in abundance, and their calcareous 

 shells form the slimy mass of the white " sandy patches " that 

 intervene between the coral banks. 



The Nullipores or coralline seaweeds form encrusting masses over 

 the reefs rather like Madrepores, but growing to a height considerably 

 above the Madrepore localities. Those on the surface are chiefly 

 pink or lilac, and so they give a characteristic appearance to the reefs 

 they infest. Other Nullipores (Halimeda) grow in deep pools or on 

 the sea-bottom, and are brilliantly grass-green. 



Everywhere on the reef sea-anemones are found in abundance. 

 Most striking are some giants belonging to the genus Discosoma. 

 Some of these had discs of between one and two feet in diameter 

 and acted the part of hosts to two species of fish and a species of 

 prawn. In Discosovm henti there were almost invariably one or two 

 specimens of a percoid fish about three inches long. When a stick 

 was thrust into the mouth of the anemone the fish swam out, but 

 when the disturbance was over returned to the seclusion of the 

 anemone's stomach. A prawn about two inches long had similar 

 quarters. Both the fishes and the prawns were brilliantly coloured. 



The tentacles of many of the reef-living anemones were con- 

 spicuous for length and branchings like the fronds of a fern. Many 

 of the anemones, especially those with peculiar tentacles, have the 

 power of stinging. 



Among the corals themselves almost every variety was found, 

 and Mr. Saville Kent has the materials for a large addition to recorded 

 species and genera ; but most interesting are his numerous de- 

 scriptions and figures of the appearance and colours of the living 

 expanded polyps. By an ingenious arrangement of his camera he 

 took many photographs of the expanded corals either in their normal 



