This is not nearly such a common creature as the smooth anemone, but you may sometimes find it in the rock-pools at low-water on our southern and western coasts. It is pale greyish yellow in colour, and has an odd way of altering its shape from time to time, so that sometimes its body is long and slender, and sometimes it is short and stout, while the disc may be long and narrow one day, and almost round the next. You can always tell it at once, if you should happen to meet with it, by looking at its fleshy feelers, or tentacles, which are marked with rings of grey and white. PLATE XLII THE THICK-ARMED ANEMONE (1) Where the coast is sandy and rocky too this anemone is often rather common. Yet very few people ever see it, because it nearly always fastens itself quite low down on the rocks which border the pools, so that at least half of its body soon becomes covered up with sand. Besides this, it has a great number of very tiny sucker-feet, not unlike those of the starfishes and the sea urchins, and with these it clings to tiny stones and bits of broken shell, which often quite conceal its upper surface, so that one really cannot see the anemone itself at all. But it is quite one of the very handsomest of all the British sea anemones, for when it is fully grown it is over five inches in width; and sometimes it is pearly white in colour, and sometimes it is green, and sometimes it is purple and brown, and sometimes it is crimson, while its tentacles are banded with scarlet and white. These tentacles are rather stout in proportion to their length, and when they are fully spread the animal looks very much like a cactus dahlia. PLATE XLII THE SNAKE-LOCKED ANEMONE (2) This is also one of the prettiest of these very pretty creatures. But it is not in the least like the thick-armed anemone, for instead of having a broad, stout body it has a long slender one; and instead of short, thick tentacles, like the petals of a dahlia, it has a bunch of almost thread-like arms, which really rather remind one of little white snakes. And when they are spread these long arms are hardly ever still, but are always waving about in the water. [Illustration: PLATE XLII 1. THE THICK-ARMED ANEMONE. 2. THE SNAKE-LOCKED ANEMONE.] When the snake-locked anemone closes up, however, you would never know it for the same creature, for it not only draws its long tentacles back into its body and tucks them away out of sight, but contracts the body itself until it is almost flat. Unless you looked very carefully at the rock to which it was clinging you would never notice it at all. This anemone is not a very common one, and is chiefly found on the rocky coasts of Devonshire and Cornwall. In colour it is almost white. CHAPTER X MADREPORES, CORALS, AND SPONGES PLATE XLIII MADREPORES (1)