It is important to have two or three snails in your globe to act as scavengers, and keep the water free from the refuse which would otherwise remain on the bottom. These little creatures are often seen moving slowly along on the surface of the glass, feeding upon the green moss or confervæ which accumulates so quickly on all the objects under water. The pipe-fish, a peculiarly shaped specimen, comparatively rare on our Atlantic coast, is worthy a place in your collection; and the shrimp, the acrobat of the aquarium, whose funny little backward movements, when the poor little fellow is frightened, create so much laughter among the little folks, must not be forgotten. Young scallops are very pretty, and when left undisturbed open their shells a trifle, disclosing a beautiful fringe of tiny blue tentacles which wave to and fro with every motion of the water.
The medusæ, also called jelly-fish, with their umbrella-like cover, and long, slender tentacles streaming downward, are pretty for a time, but do not live long after they are taken from the sea. The Cydippe and the Beroe are very lovely specimens of this class, the former particularly is noticeable for its beautiful iridescent colors. The beautiful orange colored medusa is an unsafe inmate, as he very soon kills all the fishes within his reach.
If it is possible, obtain one or more of the beautiful sea-anemones, and add it to your globe; the large, bright-colored members of this class are only to be found in the tropics, but very pretty, delicate specimens are sometimes found in our northern waters, where a rock or bit of stonework is constantly washed over by a swift current. If possible, it is better to take the stone on which they rest, as it is almost impossible to remove them from its surface without killing them. This was, however, done several times with success, and the anemones lived in our aquarium as long as they could be expected to exist in perfectly quiet water. When these creatures are at rest or frightened they draw down into little shapeless masses; but when looking for food they stretch up again, and expand on the top of the long stalk, as we may call it, a beautiful flower-like head, resembling an aster in form, and of a deep brownish-yellow color. When food is passed down to this animated blossom, it will fold its little tentacles one by one around it, and pass it down into its mouth, open to receive it, but which is entirely hidden by the beautiful petals of this delicate flower.