And even the cocoa-nut husk he does not waste; for he lives in deep burrows which he makes like a rabbit; and being a luxurious crab, and liking to sleep soft in spite of his hard shell, he lines them with a quantity of cocoa-nut fibre, picked out clean and fine, just as if he was going to make cocoa-nut matting of it. And being also a clean crab, as I hope you are a clean little boy, he goes down to the sea every night to have his bath and moisten his gills, and so lives happy all his days, and gets so fat in his old age that he carries about his body nearly a quart of pure oil. That is the history of the cocoa-nut crab. And if any one tells me that that crab acts only on what is called "instinct"; and does not think and reason, just as you and I think and reason, though of course not in words as you and I do: then I shall be inclined to say that that person does not think nor reason either. Then were there many coral-reefs in Britain in old times? Yes, many and many, again and again; some whole ages older than this, a bit of which you see, and some again whole ages newer. But look: then judge for yourself. Look at this geological map. Wherever you see a bit of blue, which is the mark for limestone, you may say, "There is a bit of old coral-reef rising up to the surface." But because I will not puzzle your little head with too many things at once, you shall look at one set of coral-reefs which are far newer than this bit of Dudley limestone, and which are the largest, I suppose, that ever were in this country; or, at least, there is more of them left than of any others. Look first at Ireland. You see that almost all the middle of Ireland is coloured blue. It is one great sheet of old coral-reef and coral-mud, which is now called the carboniferous limestone. You see red and purple patches rising out of it, like islands--and islands I suppose they were, of hard and ancient rock, standing up in the middle of the coral sea.