The great vase or seat sponges are often the habitations of animals of various kinds--shrimps, crabs, and fishes. After a hurricane I have found a windrow of them on the beaches. When the sponge is taken from the water it is fleshy and seems covered with a reddish colored mass of jelly, or it is black, brown, or yellow, as the case may be. The sponge of commerce is the skeleton, the mass of living spicules after all the animal matter has been removed and the framework, elastic and soft, thoroughly bleached. [Illustration: FIG. 17.--Sponges: _A_, Axinella; _B_, Sycandra.] The variety in shape, color, and size in sponges is remarkable and can not be appreciated until a collection of these lowly animals is seen with the individuals side by side. In such a collection one sponge, shown in Figure 18, will attract the observer for its remarkable beauty; indeed few would consider it anything but a beautiful glass vase. Some years ago one was brought to England from the South Pacific and sold for several hundred dollars. It was believed to be the work of some skilled native artist in glass. But finally some one discovered that the natives did not make them, but hooked them up from the bottom of the ocean, when they had no resemblance to the glass vases of commerce sold for enormous sums under the title of Venus's flower basket. When first brought up the vase was dark and covered with mud; then it was found that it was a sponge, and that the so-called glass was merely the interior, the framework over which was drawn the ugly exterior animal matter. It is needless to say that the enormous price of the Venus's flower basket dropped, and it can now be bought for a few cents. [Illustration: FIG. 18.--Skeleton of a sponge.] No more beautiful object can be imagined than this sponge, known as the Euplectella. It has great wisps of glasslike matter at the bottom, which anchor it in the sand or mud, and the framework appears to rise upward in whirls, the surface being made up of squares or basket work, so artificial that it is difficult to believe that it is not of human make. This vase has a top to it. It is perforated with squares, and is often a prison for various small animals, as crabs, which have passed into the interior when very small and which are now too large to escape, only their claws or feelers being seen protruding through the little portholes. The sponges in their habits show a variety of tastes. Many grow in the mud, the majority upon rocks. On the New England shores there is one of a yellowish hue which lives in the sand. It is very light, and the pores are so fine that the sand does not enter them. After a storm on Cape Cod thousands are found on the beaches, blown far inshore. Black and pure white sponges are found in fresh water as well as in salt. They increase by depositing eggs. In one stage of their development the young (Fig. 14, V.) are free-swimming animals. III. THE JELLYFISHES