himself in altogether, and closes the opening of his stolen house with one of his claws which is much larger than the other.

13. The crab holds on firmly and cannot be torn out of its stolen shell. But as he increases in size

he has to change his habitation.

This is done

when crawling along a line of shells left on a low beach by the last wave. The crab tries each likely one by slipping his tail out of the old house into the new one, till at last he finds comfortable quarters in a more roomy shell.

14. These crabs also eat garbage and dead fish, and so cleanse the coast after each retreating tide.

15. At one time it was thought that the stolen shell really belonged to the hermit crab, just as much as his own jointed armor. Crabs are as wonderful as they are useful. Just think of the difference between a man and a crab. If a man injures his leg very badly, the doctor cuts it off, and provides him with a wooden or cork one. But a crab or a lobster can grow an entirely new limb.

1. By this time we have learned how important it is to an animal to have a back-bone. All the higher animals have this series of bones running up the back, and crowned by the skull bones, for protecting the spinal cord and the brain.

2. The lower animals have no back-bones. They seem to abound everywhere. The water swarms with these lower forms of creation. The soft-bodied animals are among the highest of the boneless animals.

3. The oyster, like the clam, scallop, mussel and whelk, belongs to the soft-bodied creatures. Oysters have no limbs of any kind with which to move about. In this respect they seem little above the plants to which they attach themselves.

4. In their very early lives, or in the embryo stage, as it is called, they are in a free condition and are carried about by the currents below the

surface of the water. But they soon attach themselves to some suitable surface and from that time have no power to move from one place to another.

5. The oyster possesses a number of useful organs. It is protected by two shells, and is therefore called a "bivalve"-bi meaning "two," and valve meaning "door." These work on a strong hinge, and can be drawn closely together by a very powerful muscle When you have eaten an oyster you may see the scar inside the shell which shows where this muscle was fastened to it.

6. One shell is somewhat flattened and the other is more rounded. Each shell is lined with a smooth coat of pearl on which the soft body may rest with comfort; but outside, it is rough and made of thin plates one over the other, as if to stand rough usage at the bottom of the sea.

These flaps are really the gills, and between them is enclosed the mouth, which is shown by white lips.

8. The oyster has a mouth to eat with and gills to breathe with; and yet it has no limbs to move about, and no power to put either its lips or its gills outside the edges of its shell. How then does it feed, and how does it breathe?

9. If we place a living oyster in a shallow pan of sea-water and watch it closely, we shall see that it will soon partly open its valves, and that a current of water will run steadily between them. This current is produced by the action of a vast number of little fringe threads which are affixed to the gills. By their waving movements these cause the water to flow over and between the gills, and past the lips.

10. In sea-water there is a vast number of living creatures too tiny to be seen, besides particles of other animal and vegetable matter. These form the food of the oyster. So the current set up by the oyster's own gill-fringe carries to it both food to eat and air to breathe, for there is always air in the water of the sea.

1. As the demand for oysters is very great it becomes necessary to arrange for a large supply. In order to meet this demand, for food, as well as for the nacre, or mother-of-pearl, that lines their shells, oyster beds are made in favorable places, and planted with young oysters.

2. These young creatures are very sensitive to any great change in temperature, or to any unusual movement of the currents, and many perish from such disturbances. Young oysters require clean surfaces to which they may attach themselves, as well as a sheltered position, and oystermen are very careful in the arrangement of these things.

3. Pieces of broken shells, pebbles, bundles of sticks tied together, and broken crocks are scattered over the sea-bottom, in order that the young oysters may fasten themselves to them and live Along coasts, various seaweeds, or

and grow.