But we are the highest of the type--that is, we men--and the rest of the tribe are all lower. And the lowest of all backboned animals we call fishes. And we shall know a fish when we see one because the hard parts or skeleton are on the inside, and he stays in the water, breathing the air which is dissolved in it, and he has never any toes or claws or feathers. He breathes with gills and he swims with fins. He has no hair or feathers on his body and when he has any cover on his skin at all it takes the shape of scales. A fish is a water backboned animal. A backboned animal is called a vertebrate. A fish is therefore a water-vertebrate. There were fishes before there were any other kind of vertebrates. They have been on the earth longer than birds or beasts or reptiles. They came first, and we have good reason to believe that the fishes are the ancestors of all the others. But when the forefathers of the land animals found means of keeping alive on the land, so many new opportunities opened out to them and they found so much variety in their surroundings, that they throve and spread amazingly. And there came to be many kinds of them, of many forms, while the rest of the tribe kept in the water and stayed fishes. [Illustration: COMMON SUNFISH. Life-size. COPYRIGHT 1900, BY A. W. MUMFORD, CHICAGO.] And there was always a host of these, and nearly all of them had fishes for their food. So they fought for food and fought for place. Those who could swim fastest got away from the rest, and those who could move quickest got the most to eat. Those with the longest teeth were present at the most meals, and those with the biggest mouths dined with them. And some escaped because they had hard, bony scales, too tough to crack. Some were covered over with thorns, and some had spines in their fins, which they set erect when their enemies would swallow them. And some had poison in their spines and benumbed their enemies, and some gave them electric shocks. Some hid in crevices of rock, or bored holes in the mud, and lay there with their noses and their beady eyes peeping out. Some crawled into dead shells. Some stretched their slim, ribbon-like bodies out in the hanging sea-weed. Some fled into caves, whither no one followed them, and where they lay hid for a whole geological age, until, seeing nothing, they had all gone blind. And some went down into the depths of the sea--two miles, three miles, five miles--I have helped haul them up to the light--and these went blind like the others, for the depths of the sea are black as ink and cold as ice. And even there they are not safe, for other fishes go down there to eat them. And some carry lanterns, large, shining spots on their heads or bodies, sometimes like the head-light of an engine. And with these flashing lanterns, these burglars of the deep hunt their prey. And these are hunted by others fish-hungry, too, who lurk in the dark