The color of this shark is slaty blue above and white beneath. THE WHITE SHARK Even larger and more dangerous still, the great white shark, or Rondeleti's shark, is one of the most formidable creatures that roam the seas. It often grows to a length of thirty-five or even forty feet, and weighs ten or twelve tons, while one snap of its huge jaws will shear off a man's legs or cut his body in two. This enormous fish is found in all the warmer parts of the sea; and in general sharks, and especially the large ones, belong to the tropical rather than to the colder seas. THE HAMMERHEAD A huge and much-to-be-dreaded creature, of curious appearance, this fish has its head formed just like that of a hammer, the eyes being placed at each end of the projecting lobes. It grows to a length of fifteen or sixteen feet, and is very fierce and savage, attacking human beings without the least hesitation. It is nearly always found in the tropical seas, but has been several times captured off the coasts of New England. THE THRESHER Growing to a length of ten or twelve feet, the thresher is a remarkable shark. It is common in the Mediterranean Sea and the Atlantic Ocean. It feeds chiefly upon herrings, darting into the midst of a shoal and snapping them up in hundreds. What it is specially famous for, however, is its habit of attacking whales. For this purpose several threshers will unite together, leap up into the air, and strike tremendous blows with their long tails upon the whale's body as they fall back into the sea. This naturally terrifies the whale, and he dives under water in order to escape from his tormentors. Knowing that he must very soon rise again, however, they wait for his reappearance, and then attack him again in the same way. This happens again and again, until he is quite worn out by his exertions, and by the impossibility of remaining long enough at the surface to breathe properly. Then if any swordfishes happen to be in the neighborhood, they come and attack him too, driving their long swords deep into his body. Before long the whale is dead, and both threshers and swordfishes are tearing great strips of flesh from the carcass and greedily devouring them. SAW-FISHES Next to the sharks come the saw-fishes, which have the upper jaw drawn out into the form of a long, narrow beak, set on either side with a row of large, pointed teeth. So it really looks very much indeed like a saw. The fish uses this curious weapon by dashing into the midst of a shoal of smaller fishes and striking them right and left with its saw. In this way it is sure to disable a good many, which it then swallows leisurely one after the other. Saw-fishes are found in all the warmer seas, and sometimes grow to a length of fifteen or twenty feet. RAYS