Not only are the growth-forms of corals varied as those of plants, but the details of the polyp cups are well worth attention. Typically the surface of the coral is covered with round depressions, which may be minute, as in _Porites_, or half an inch across as in _Caryophyllia_ and the dome-shaped species shewn on Plate XXVI. All are partially filled up by complicated series of radial plates, and a central core, best seen in the illustration of _Caryophyllia_, and the arrangement and ornamentation of these form an endless variety of patterns. In other cases the depressions, instead of being round, are elongated, forming meandering grooves over the surface, which, from their superficial likeness to the convolutions of the human brain, give the name “Brain coral” to certain kinds. In others again the walls of the cups disappear, and the system is reduced to a network of plates, converging to the centres of the polyps, or these may be so thickened and flattened that the spaces between them appear as fine lines, tracing a lace-like pattern on the surface of the stone. One is tempted to write a whole book on the beauties of corals and coral animals but must refrain; one other form is however so interesting, and at the same time so common, that a short special description is given. In many sheltered water gardens may be seen numbers of what look like overturned, stalkless, mushrooms. On handling they are found to lie loose on the sand and to be stony corals. They are in fact single polyps of phenomenal size, being up to six inches across, and the radiating plates, which so resemble the “gills” of a mushroom (hence the name of this genus, _Fungia_) correspond to those already seen in the other corals illustrated. The cup wall is however absent. The life history is as strange as the coral that results. The young polyp produces at first a quite ordinary, small, cylindrical cup, Plate XXIX, which is fixed to a stone in the usual way. After reaching a certain size this swells at the top into a disc, like a mushroom on its stalk, except that the mushroom head is turned wrong side up. A little later this head falls off on to the sand, where it continues to grow into the big _Fungia_ discs first met with. This, however, is not the death of the original polyp, which goes on growing new heads which in turn fall off, _ad infinitum_! Many attempts have been made to visualise the beauties of a coral garden, in poetry, romance, and works of sober science. I can make no claim for my own picture, but that perhaps it is written with better acquaintance than is generally possible to poets and romanticists, and that it is free from exaggeration, as the writings of a biologist should be.