456 NATURAL, SGIENGE. 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 débris, 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 bea 
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 Dzéscosoma. 
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 Discosoma kenti 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 
