All this talk about the burrowing of animals abroad must have made you think of that little master-builder in our own fields and gardens-the mole. He is as wonderful a workman as any of them. Indeed, no burrowing animals make a more beautiful home than this little friend of the farmer. All that we see from the top are little mounds of earth, which we call mole-hills. They are simply shafts which the mole has tunnelled from below to throw up the soil which his great claws have dug. THE GREAT WONDER THAT LIES

BENEATH A MOLE-HILL

Nothing but a picture can give you an idea how wonderful are the works of the mole. He has tunnels running in all directions, all made on the strongest and most beautiful plan. Some are short cuts by which he and his family can dart away in time of danger. Others are long highways leading, on careful plans, all about his underground estate. He has a splendid central hall, arched over under a vaulted roof, and with five or six entrances. He has a proper nursery for his children. If you have tried to make a building of sand or soil, you know how hard it is to keep the place from tumbling down. The mole has only soft soil in which to work, but in it he makes his great tunnels and his lofty hall smooth and hard; and they do not fall in, even though great rainstorms should soak the ground.

That is the mole's work. His pleasure is in eating and in getting food for his family. He eats worms and grubs, which would do great injury to the farmer. Of course, he can miss his way, and throw up hills which will spoil the finest lawns or pastures. That is bad, but he makes this good by his work in the borders and in the fields. THE MOLE MAKES A TUNNEL AND SINKS A WELL

How

To show how he can tunnel, this story will help you. A gentleman has a big conservatory, in which he grows peaches and strawberries and grapes. He could not imagine how it was that the soil used to get so cut up and tossed about in the conservatory. But his gardener found that moles were at work. They had runs out in the the grounds, and, finding that worms and grubs were to be had in the soil of the greenhouse, they burrowed under the

foundations of the building and into the conservatory. This could not be allowed, for it did damage, so traps were set. In a fortnight the gardener caught a dozen moles in that conservatory.

Have you heard people say as blind as a mole"? They do not know anything about the mole when they say this. The mole, like the bat, which is also believed to be blind, can see. It has tiny eyes set deep in its fur, so that they shall not be injured by the soil.

You would not die of thirst if you could set a mole to work as engineer. It's keen sense of smell enables it to find water at once. It sets to work with its splendid claws, and sinks a well to where the water is.

If you find a long, little burrow just under the surface of the ground, you must not think that you are looking at one of the walks of our little friend the mole. That may be the tunnel of the shrew, which makes a nice little round passage with a snug nest at the end of it, but not on such a big scale as the mole's. The shrew is a pretty little animal, not quite three inches long, with a long, pointed nose, and a tail about an inch and a half in length, which does not taper away as a mouse's does.

THE

LITTLE SHREWS THAT FIGHT
UNTIL ONE KILLS THE OTHER

It is supposed to be terribly savage, but it is not unless one male shrew meets another male shrew. These two fight until one is killed. Otherwise the shrew is a cheery, good-tempered little fellow, and not so fierce as the mole. It has many enemies, and so is bound to make some efforts to save itself, or the whole family would soon be killed. Owls will eat it, but, though cats will kill it, they will not often eat it.

This shrew lives only on land, but there are shrews which live in the water as much as the beaver does. We have two sorts of water-shrews in England, but neither is so remarkable a shrew as the desman. This is a shrew with webbed feet, and with a tiny trunk for nose, like that of the smallest of small elephant's trunks. The nose serves the desman in many ways.

The food of the desman consists of small fish, insects, worms, and vegetable food, most of which it can get in the water where it passes its day.

The next story of animals is on page 785.

IF

we think of a number of different animals, such as an elephant, a bird, a bee,

and a serpent, we see how very different the bodies of animals may be, and yet, perhaps, we shall find that even here there is order, and that the points in which the bodies of different animals agree are more important than those in which they differ.

If we could summon before us all the animals that exist, and look at them carefully, we should be able, in spite of all their differences, to divide them up into two great classes, so that all the animals in one class would be far more like each other than they would be like any animal in the other class. In the one class we should place all the animals that have a backbone, and in the other all that have not.

It is true that we should find a very few animals about which we could not be sure, or, rather, which we should have to place between the two classes, for there are a few kinds of animals still living on the earth which have only half a backbone, or something that looks like a sort of rough model of a backbone. These animals are, of course, immensely interesting, because they teach us how the backbone began, and we need not mind that we cannot put them into classes.

Well, now, let us begin first with what are much the least important

class of animalsthose which have no backbone. We shall deal with them first, because they actually came first. For very many ages there were animals of many kinds living in the sea, and others living on land-these last always cold-blooded-which had no backbones; and if you had searched the whole earth and all the seas you would not have found a backbone anywhere -any more than you would have found a brain. You might as well have gone looking for a brain or a backbone amongst the plants as in the animal world of those distant days.

These animals which have no backbones are very difficult to arrange in any kind of order. Some of them are more wonderfully made than others, and have not existed on the earth so long. But they differ from each other so widely that it is really quite impossible to arrange them in a simple order. In any case, however, these backboneless animals, such as insects, oysters, and worms, are very humble and unimportant.

As we have hinted, none of them has a brain. This does not mean that they cannot feel, nor that some of them, such as the bees, are not very wonderful in many ways; but, after all, until that great thing called the brain came into existence, no great progress could be made. So we need

here say nothing more about the backboneless animals.

Nor need we here say anything about the curious kinds of animals which show us the first hints of a backbone. In some ways they are among the most interesting animals in the world, because small beginnings that lead to great things are always interesting. But here, whilst not forgetting that the earliest backbones were very rough and imperfect things, we may begin with those animals, very well known to everyone, in which first a complete backbonethough a very simple one-is to be found, and these are the fishes.

THE

FIVE GREAT CLASSES OF ANIMALS WITH BACKBONES

If now, beginning with the fishes, we study all the different kinds of backboned animals that exist, we find that though there are many thousands of them, yet they can all be arranged in a very simple way. More than this, it is possible, quite certainly, to show which class came first, which last, and so on. Many hard-working men are trying to arrange the animals that have no backbone in this way, but they have not succeeded yet.

Here, then, are the five great classes about which there is no doubt of the backboned animals-fishes, amphibia, reptiles, birds, mammals. Now, some of these words are strange, but they are really not difficult, and we shall easily explain them. For instance, if you have not heard of amphibia before, at any rate you know a frog when you see it, and if you have never heard of mammals, it is easy to remember that mammals are animals which feed their young by means of milk, as, for instance, a cow, which feeds her calf. A human mother feeds her baby in the same way, and human beings are by far the highest kind of mammals.

THE

HE HISTORY OF THE ANIMALS THAT
HAVE BACKBONES

Now, there are very great differences between a fish, a cow, a sparrow, and a frog; but yet they all agree entirely in the main lines on which their bodies are made, because they all have a backbone. And we shall see soon that they agree in many other things besides. It is true that the fish is cold-blooded, and breathes water (or, rather, the air dissolved in water), whilst a Cow or a

sparrow is warm-blooded, and breathes air, but so far as the great history of the body is concerned, all these backboned animals are far more like one another than they are like any animal that has no backbone.

Now we want to trace upwards, if we can, the history of these various kinds of backboned animals. The first, we are certain, were the fishes, and though the fishes have given rise to so many creatures far more wonderful than themselves, yet, in the seas in which they first came into existence, they still thrive. There are many

different kinds of fishes, as we all know, though all the fishes that we eat are very closely related to one another.

There are many other kinds of rare fishes which few of us have ever seen. But we may take all the fishes as a group, and remind ourselves of the chief facts about them. They are the first animals with backbones; they live in the water and breathe the little air they find in water; they are therefore cold-blooded, and on no account must they be confused with certain strange mammals like the whales, which live in the water but breathe the air above it, and, like all mammals, are warmblooded.

THE ANIMALS THAT LIVE IN THE SEA

we

ARE NOT ALL FISHES

Again, all fishes have a backbone, which is the principal part of what call their skeleton; and this skeleton is inside their body, and is covered with soft parts like muscle and skin. This fact, the possession of a skeleton inside the body, built upon and around the backbone, is true of all backboned animals.

Just as on no account whatever must we confuse the fishes with animals

like the whale, which is a newcomer on the earth compared with the fish, so we must here give up, once and for all, the utterly wrong notion that all the animals found in the sea are fishes. It is simple nonsense to think of a crab, or an oyster, or a star-fish, or any kind of so-called shell-fish, as true fishes. On the contrary, these animals have existed ages and ages longer in the sea than any fish. They have no backbones, no hints of a brain, and are as inferior to the fish as the fish is to a cow. We have no more right to

call them fish because they live in the water than we have to call a worm a bird because it breathes in the air.

Now, backboned animals very often have limbs-fore legs and hind legs, or arms and legs, or wings and legs and the making of these limbs is one of the most important facts in the whole history of the body. Soon we shall trace this up from the fishes.

The nearest approach to anything like limbs that we can find in fishes is to be found in their fins. Now, we believe that certain fishes, which had a long fin stretched right along each side of the body, from head to tail, played a great part in the making of the bodies of higher and later animals, for from these long side fins there were gradually formed, as the ages went on, two pairs of limbs, one pair in front and one behind, which are to be found after this time in all backboned animals.

THE FISH THAT GROWS INTO

AN ANIMAL

Now, you remember what we said lately about the great step taken by life when first it "swam ashore." We know even now certain fishes which can get along for some time in the air, and they give us a little hint of what happened, especially since some of these fishes are very clever at hopping along in the mud. If now we turn to the next class of backboned animals, which have that difficult name amphibia, we shall be able to guess what happened. The word amphibia is really a Greek word, and all it means is "both-life." It is just a word made up to say that animals of this kind, such as the frog, lead both kinds of lives-life in water and life on land. Now, they do not lead both kinds of life backwards and forwards, one way or the other as they please, but each amphibian begins by leading the one kind of life, and goes on by leading the other. So it gives us a hint as to the history of life in the great chain of backboned animals.

When the frog is very young, it is called a tadpole. This lives in water and breathes water. If it never went any further, we should properly call it a fish. So long as it is a tadpole it is a fish; but, of course, if it were no more than a fish it would live in water all its days. The tadpole does not do this, but after a time it begins to make

great changes in itself; there begin to be hints of limbs and, what is even more important, of lungs; and at last the little tadpole grows up into a frog, which is not a fish, which has arms and legs, or fore limbs and hind limbs, and which breathes air by means of lungs.

HE GREAT-GRANDPARENTS OF THE

TEROUS LAID THE PLAN FOR ANIMALS

Not only so; but this frog has hands as we have, each having four fingers and a thumb, whilst it has five toes on each of its feet. Indeed, ages and ages ago, the first frogs, or the great-grandparents of the frogs we know now, laid down the plan of the kind of limbs which all backboned animals since then have had; though some of them, like the bird, do not keep this kind of five-fingered limb all their lives.

Now, when the frog is grown from the tadpole, into a back-boned animal with four limbs, breathing air by means of lungs, it is really very like, indeed, to certain of the next class of backboned animals, which are called reptiles. It is not like a snake, but it is like a little lizard-and especially if that lizard has no tail. Indeed, the simplest way of looking at this is to think of the amphibia as fishes when they are young, and reptiles when they are grown up. The young frog or tadpole is practically a fish, because it is made as a fish is made, and does what a fish does. The grown-up frog is practically a reptile, because it is made as the reptiles are made, and does what they do.

WHE

HEN THE Reptiles were the
MASTERS OF THE EARTH

Now we leave the amphibia and may pass on to the next class of backboned animals that appeared upon the earth, which were the reptiles, and of these we need not say much, except simply that a great many of the reptiles have gradually lost their limbs and have become very long and round and crawling, until at last they took the shape of snakes and serpents. Nevertheless, snakes and serpents in their very tiniest and earliest stages show that they are the children of creatures that had limbs, and we are quite certain of this. A snake has no limbs that you can see, not for the reason that a worm has no limbs for a worm never had any-but because it has lost