An examination of any typical coral fragment, living or dead, massive or branched, shews that the surface of the stone is shaped into little cups, which may be large (half an inch or more in diameter) or very small; they may entirely cover the surface or be scattered at intervals, be sunk below the general level or project boldly from it (see the figures of corals on Plate XXVI). In any case, all ordinary corals consist of a multitude of such cups borne upon a common mass of the same stony material, and each cup may be regarded as the remains of one individual “polyp” as the coral animal is called. It will be a simpler way of gaining an idea of what a coral polyp really is to take a least specialised member of its class, one in which each individual lives disconnected from its fellows and does not secrete the complicated skeleton characteristic of the stony corals. Fig. 52 shews a “sea-anemone” in no material respect different to those which Gosse has so beautifully figured from our own shores. It is seen to be a graceful translucent cylinder fixed by its base to some chance stone or shell. This extreme simplicity of form gives the living animal a by no means inconsiderable beauty. The free end of the cylinder bears a circle of what look like hairs, but which are found on testing to be highly sensitive to touch and are surprisingly adhesive for organs of such transparent delicacy. They are consequently better named the tentacles, their function being to adhere to and close down upon any little water-flea or such-like animal that has the bad luck to swim against them. They are also provided with stinging cells which are used for paralysing their prey and for defence. In the centre of the disc is the mouth, a simple opening, a mere hole in the top of a sac. Our polyp, or anemone, has no organs of locomotion, no organs of sight, taste or hearing, indeed no brain. It has at any rate the rudiments of a nervous and muscular system, for it is able to move its tentacles all towards that one which has captured prey and assist it in conveying the food to the mouth. The body is sensitive all over, for any part when touched will contract, and a violent shock causes the tentacles to fold together and the whole animal to close down to a shapeless hemispherical mass. This is the limit of its sensory and muscular powers, two or three muscular movements, a few of the simplest reactions to outside influences, nothing that could be called even the sense of touch.