In the deep sea lives a giant form, the Umbellularia, four or five feet high; and there are many more, all of which add to the lights of the deep sea. Near allies of these attractive forms are the comb bearers, free-swimming, jellylike forms of great beauty and grace. I have kept the radiant Pleurobrachia in a tank where I observed its wonders and beauties. The one known as Veretillum (Fig. 43) is very beautiful and a marvelous light giver. VI. THE STONE LILIES A number of years ago I took a number of walking trips over that section of New York state known as the Catskill Mountain region. The start was made at the mouth of Catskill Creek, which was followed up into the mountains until we came to a peculiar light, slate-colored rock. This rock, where the stream had washed the earth away, was dotted with little disks (Fig. 44), which being harder than the rock itself had been weathering, and stood out in high relief. A mile or two from the river the rocks were covered with these disks, in fact, seemed to be made up of them. Some were large, some small, as if millions of pipestems had been cut into sections and scattered about. [Illustration: FIG. 44.--Sections of fossil crinoid stems, Catskill Creek.] These disks told an interesting story. We read by them that ages ago the region now covered by farms and summer resorts was the bottom of a shallow, tropical sea. We could go further and describe even the appearance of the bottom of that sea, and what grew and lived there. Scattered about on the rock were myriads of shells, corals, teeth, fish bones, and a variety of objects, all the remains of animals which once lived in this ancient ocean. We find that the little disks fit together, and collecting them, pile them up, forming a stem a foot or more long. Among them we find one which is attached to a rootlike object, and this is placed at the bottom. Near by we find a flowerlike or budlike form (Fig 45), which may well serve as the flower of this stem, and so we add it and produce a striking resemblance to the crinoid shown in Figure 46. This is an interesting and beautiful animal which was one of the commonest forms of the ancient seas. It grew in groves and masses, as we may see by the vast numbers strewn in the old ocean bed; and when they died, they were scattered here and there and hardened into the old bed. [Illustration: FIG. 45.--Fossil crinoid.] [Illustration: FIG. 46.--A living crinoid (_Pentacrinus_).]