The crater of Haleakala is said to be the largest extinct crater in the world. To follow all its outlines would lead one a distance of more than twenty miles, but it is so irregular in shape that one gets only a poor conception of its extent in a view from its brink. At its widest part it cannot be more than four or five miles across. It was evidently formed by the whole top of the mountain having been blown out or else sunk down in recent geologic times. The fragments of jagged rock that thickly strew the surface all about the summit look as if they might have fallen there. The floor of the interior of the crater is thickly studded with many minor craters, through which the internal fires found vent after the crater as a whole had ceased to act. They are of the shape of huge haystacks, with a hole in the top, and looked soft and yielding in outline, and in color as though they were composed of soot and brick-dust. One of them is much larger than any of the rest. I thought it might be two hundred feet high. "It is eight hundred," said our guide; yet its summit was more than a thousand feet below the rim upon which we sat. There has been no eruption in Haleakala since early in the last century. Over a large area of the interior the black lava, cracked and crumpled, meets the eye. Miles down one of its great arms toward the sea, we could see the green lines of vegetation, mostly rank ferns, advancing like an invading army. Far ahead were the skirmishers, loose bands of ferns, with individual plants here and there pushing on over the black, uneven surface toward the secondary craters of the centre. Vegetation was also climbing down the ragged sides of the crater, dropping from rock to rock like an invading host. The ferns, those pioneers of the vegetable world, appear to come first. Their giant progenitors subdued the rocks and made the soil in Carboniferous times, and prepared the way for higher vegetable forms, and now these striplings take up the same task in this primitive world of the crater of Haleakala. Their task is a long and arduous one, much more so than in those parts of the island where the rainfall is more copious; but give them time enough, and the barren lava will all be clothed with verdure. When decomposed and ripened by time, it makes a red, heavy soil that supports many kinds of plants and trees.