Sea-Urchin

a marine relative of the starfish. A hollow apple with a mouth at the stem end and a second opening at the blossom end, surrounded by a rigid shell covered with spines like a chestnut bur, is a loose, rambling description of the sea-urchin. Like the starfish it moves by muscular water tubes controlled from a central reservoir. It can climb steep surfaces and hold to timbers or the faces of rocks. In addition to being a genuine curiosity, the sea-urchin is an animal of first importance to scientific investigators. Its eggs and spermatozoa lend themselves very well to the investigation of laws of animal development. In Italy the eggs of the sea-urchin are eaten and considered a delicacy at table. See Starfish

Sea Water. It is well known that the water of the ocean is much denser than fresh water, owing to minerals in solution. Few people have any idea, however, of the large amount of mineral matter that has been washed out of the lands by rains and carried by streams to the sea. The ocean covers about 145,000,000 square miles. The average depth is thought to be not far from two miles. In that case, the cubical content of the ocean is not far from 290,000,000 cubic miles. The following statistics relating to the contents of a cubic mile of sea water are gleaned from an interesting article contributed by F. E. Mariner to Popular Mechanics: