[Footnote 46: To obtain a specimen of coral of this beautiful snow-white colour it is necessary to remove the flesh from any living colony, which is usually coloured brown or yellow, by rotting the same for a week in sea-water in a bucket. Cover the bucket to keep out dust, and change the water a few times to reduce the smell. The last traces of decayed flesh are removed by dashing buckets of water on to the coral. Rinse in fresh water. Or the specimens may be dried _thoroughly_, rotted in water after return to Europe, and finally bleached with hydrogen peroxide.] [Footnote 47: See for instance, among other literature by the same author, “The Fauna and Geography of the Maldives and Laccadives,” Cambridge University Press, and “The Percy Sladen Trust Expedition to the Indian Ocean,” by J. Stanley Gardiner, M.A., F.R.S., etc., _Transactions Linnean Soc. Zoology_, Vol. XII., pp. 35, 51, and illustrations on Plate IX, and on pages 128 and 135.] [Footnote 48: The duller coloured and peculiarly shaped “bladder” or “parrot” fish, _Tetraodon_ or “four tooth” is distinguished by its peculiarly rounded shape and alteration of scales into spines. Though its teeth are very similar to the coral eater, _Pseudoscarus_, it eats softer animals, e.g. Ascidians and Echinoderms, and sometimes shell-fish.] [Footnote 49: Includes the whole oyster and bivalve shell-fish family, and many other less generally known forms of life.] [Footnote 50: Owing to the practical absence of tide in the Red Sea the boat channels of the fringing reef are discontinuous, so that at intervals the canoe men must wait for favourable weather and put out to the open sea. In Zanzibar, e.g., one can travel the whole 60 miles of the east coast within the reef but for the crossing of one bay, except at lowest spring tides. Some of the deeper parts of the boat channel of Red Sea reefs are due to faulting (see next chapter) as may be also a very peculiar reef channel just north of Mombasa Harbour.] [Footnote 51: For the qualities and formation of this rock see page 111.] [Footnote 52: The absence of similar stones from all other parts of the reef is to be accounted for by their being subject to the continual friction of strong sand-laden currents, while those on the raised edge are exposed to waves of clean water for a portion of each day only.] [Footnote 53: These tubes form a mass by coiling loosely together like a cluster of worms, though the animal which makes them is exactly like those that have regular spiral shells and move about freely, e.g. the whelks. The young _Vermetus_ has a shell like a young whelk, but as it then fixes itself down, the shell degenerates, and grows into the loosely coiled tube of the adult mollusc. Nothing could be more different than the body of a _Vermetus_ and that of a worm, the resemblances between the shell of the one and the tube of the other being pure coincidence.]