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The Cretaceous period receives its name from the great deposits of chalk which are exposed on either side of the English Channel. It was here in southern England and northern France that these formations were first studied. However, it must be understood that chalk is the exception and not the rule in this period.

The Cretaceous was a long period and is divided into an Upper, or Later, and a Lower Cretaceous. During some of the period, a great part of North America was under water. The Gulf of Mexico overflowed and covered most of the southern United States, Cuba and Mexico. Texas, Oklahoma, Kansas and Wyoming gradually sank, and the waters crept across Canada and Alaska to join the Arctic Ocean. This great inland waterway known as the Colorado Sea, was more than a thousand miles across at its widest point, between Idaho and Wisconsin. Eastern Canada and the northeastern United States remained above sea level.

During the Cretaceous period, most of Europe was under water, and in the water the rocks were being deposited either as sandstone, clay or chalk, so that we find Cretaceous rocks in detached areas over most .f the continent, giving a record of the seas, lakes and rivers of the period. A map of Europe at that time would show the greater part of Spain, Italy, and the whole of Belgium, Holland, Prussia, Hungary, Switzerland, Rumania and north Russia as an almost continuous sheet of water. According to archeologists this flooding of the land during the Cretaceous was probably the most marked spreading of the oceans that has ever occurred.

Cretaceous rocks are found not only in Europe but all over the world - in the Arctic oceans, India, Japan, North America, South America, Australia and New Zealand. In California there are strata of Cretaceous rock as thick as thirty thousand feet. During parts of the period,, the seas were very shallow, and some of them became fresh. The rich coal beds of Alberta were laid down during this period.

The chalk rocks, like most other limy rocks, are composed of the limy shells of myriads of microscopic sea creatures. If a little chalk is ground up with water, it will be found to be full 0f these tiny shells (foraminifera), so small that about two thousand placed end to end stretch only about an inch. A cubic inch of this chalk will contain thousands of millions of shells. The seas of the period must have been swarming with these tiny sea creatures, and in the course of ages they accumulated on the floor of the sea and formed the white cliffs of Dover and all the other chalky rocks that we see now in the Cretaceous System. Because chalk beds formed during any period other than the Cretaceous are seldom found, this period is often known as the Age of Chalk.

The vegetation of the Cretaceous period is of special interest, for it was in the middle of this period that the first flowering plants appeared. These plants quickly spread throughout the world and took the place of the horsetails, ferns and cycads as rulers of the plant kingdom. The Cretaceous forests must have been very much like the forests we know to-day, although much richer and more luxuriant. Magnolias, myrtles, tulip trees, sassafras, oaks, beeches, elms, willows, palms and many other modern trees flourished in the warm, moist climate. When they died, they left impressions in the deposits of the Cretaceous period so that we have a record of them to-day. The Cretaceous rocks of northern Greenland have yielded up nearly two hundred species of plants, among them the breadfruit tree, which now grows only in tropical regions. More than a thousand Cretaceous plants have been discovered in North America. Because the flowering plants spread over the world so rapidly, the plants of Europe during this period were about the same as those growing in Greenland and North America.

The Cretaceous seas swarmed with life. In addition to the foraminifera, sponges, star-fish, sea-urchins, corals, polyzoa and crustaceans abounded. Sharks were quite common. Probably the largest fish was portheus, who reached a length of from eighteen to twenty feet and had a jaw a yard long, every inch of which was lined with long, sharp teeth.

SOME STRANGE REPTILES OF THE CRETACEOUS SEAS

Like the Jurassic, the Cretaceous period was an age of great lizards. One of the most interesting of these was the mosasaurus, which, when first discovered at Maestricht in Holland in 1780, was a great puzzle to the naturalists. At various times it was considered a fish, a whale and a crocodile. It was left for the genius of Cuvier to identify it as a reptile. The mosasaurus first found was only twenty-four feet long, but specimens have since been discovered about fifty feet long. These great creatures had fin-like paddles with which they propelled themselves through the sea. Like snakes, they had sharp teeth on the tops of their mouths, while their enormous jaws were jointed in such a way as to allow them to gape horribly and to swallow tremendous morsels. They must have been very formidable creatures. At the close of the Cretaceous they completely disappeared.

An amazing creature, too, was the elasmosaurus, which has been found in the chalk deposits of Kansas. It was sometimes fifty feet long, and twenty of this was a slender neck. It has been said that it probably often swam many feet below the surface “raising the head to the distant air for a breath, then withdrawing it and exploring the depths forty feet below without altering the position of its body.”

Another sea-dweller of the Cretaceous period, the turtle, has left a great number of descendants. The largest Cretaceous turtle is called archelon. It was twelve feet long and almost as wide. It swam by means of large flippers half as long as the body.

The iguanodon may perhaps be considered one of the most characteristic land reptiles of the period. It was first discovered in the Cretaceous rocks of Sussex; but no less than twenty-nine of them were found in a Belgian coal-mine. It was a herbivorous, or plant-eating animal, thirty or more feet long from nose to tip of tail, had a duck-like bill, and walked on its hind legs like a kangaroo. In the Royal Museum in Brussels nine skeletons of these strange creatures are mounted in one room. A North American relative of the iguarodon was the trachodon, a reptile that was as common during the Cretaceous period as deer were a few years ago. There is on exhibit at the American Museum of Natural History in New York the mumified remains of a trachodon. When he died millions of years ago, this animal must have lain exposed to the hot sun in a dry climate until his body was completely dried out and mummified. Then it was covered over by wind-blown sand which eventually became solidified into rock and preserved this unusual specimen. The trachodon skin was not so very different from the skin of some of our modern lizards.

THE MOST TERRIBLE CREATURE THAT EVER WALXED THE EARTH

Another Cretaceous dinosaur, tyrannosaurus rex, “King of the Tyrant Reptiles,” has been described as the most destructive life engine that ever lived. He roamed the ancient plains of Montana and Wyoming. His head towered from eighteen to twenty feet above the ground and his entire body was almost fifty feet long. His jaws were armed with curved, pointed, and double- edged teeth, the longest of which was six inches. Great claws enabled him to rend the flesh of his victims.

One of the most curious dinosaurs of the Cretaceous was the triceratops, a creature with a skull eight feet long and armed with three horns. Two of these horns were above his eyes and another grew from the middle of his snout. His skull projected backward over his neck to form a great bony collar that must have furnished an excellent protection against the attacks of such fierce animals as tyrannosaurus.

Besides the pterodactyls of the Cretaceous, there were a few true birds, some with teeth. Mammals were not yet plentiful.

Both atoms and window panes will be smashed when they are struck forcibly by a suitable object. Though for centuries mischievous boys have known the secret of smashing a window pane by means of pebbles flung by a sling, it was only within recent years that scientists learned how to smash the atom, a feat which was for a long time considered impossible.

An important clue to the solution of the mystery of atom smashing was obtained late in the last century, when it was found that atoms of elements such as thorium and radium were self-splitting, like a fire-cracker that blows itself into bits. Scientists studied these radioactive elements, as they were named, for here was the first evidence that one element could be changed into another.

In 1919 Lord Rutherford bombarded nitrogen gas with the alpha particles which are shot out by radioactive elements as they undergo certain of their changes. Some of the nitrogen was changed into oxygen. For the first time in history, man had succeeded in changing one element into a different one. In this way did modern science realize the dream of the ancient alchemists who strove in vain to change common metals like copper and lead into precious ones like gold and silver.

Today atoms are being changed by means of huge atom-smashing machines of which several types exist. Perhaps the best known and most widely used of these machines is the cyclotron, an atom smasher invented by Ernest Orlando Lawrence of the University of California. Just as a youngster twirls a sling overhead and lets the pebble in it fly at a tin can on a fence, so does the cyclotron whirl atomic projectiles round and round until they have acquired great velocity, then hurls these electric pebbles at a chosen target.

Like a store of pebbles which a boy may carry in his pocket for use in a sling, the cyclotron in a roundabout way gets its atom- smashing bullets from a gas at low pressure contained in a tank. If the gas is hydrogen, the cyclotron hurls protons; if helium is in the tank, alpha particles are fired; and if the gas is heavy hydrogen, deuterons are shot at the target.

Besides the cyclotron, another type of atom smasher favored by scientists is the Van de Graaff electrostatic generator, by means of which small electric charges are collected from endless belts. These charges are stored until high voltages are created to send atomic bullets against atomic targets.

Neutrons are produced in relative abundance from the nuclei of atoms bombarded by deuterons or alpha particles. These neutrons are in turn directed at other objects, such as atoms or cancer cells. The neutron makes a good atomic bullet because, though it has the mass of a proton, it lacks an electrical charge and hence it is not repelled by the electrical forces around an atom’s nucleus.

Atom-smashing devices have changed most of the elements into other elements, and have made many elements artificially radioactive. The cyclotron has changed common table salt into a radioactive salt which has an activity equivalent to the radium emanations from four million dollars worth of radium.

Such radioactive salts have been used in the treatment of cancer patients. Since the radioactivity dwindles quickly, the salts may be taken by mouth or may be injected. Actual radium used in this manner would be dangerous, as the activity of radium continues for so long that the healing effects would be overcome by the destructive effects on healthy tissue.

By means of the cyclotron gold has been created from platinum. This is certainly not a practical method for obtaining gold, since the platinum used as the raw material is more expensive than the gold. We should not consider the transmutation of a more valuable element into one less valuable as a foolish or wasteful experiment, however. As Dr. Lawrence remarked, “The information we are getting is more valuable than gold.”

Bismuth, an ordinary element, has been changed into a long-lived form of radium by the cyclotron. Neutrons are being used instead of X-rays and radium to kill cancer growths, though it is still too new a treatment for scientists to be sure of its worth. Many atoms hit by neutrons have been split with a tremendous release of atomic energy. If such explosions could be created efficiently on a large scale, we should have at our command a new source of energy greater than any now used.

The tongues of some moths and butterflies are as long as their bodies. This is a wonderful adaptation of nature, enabling the insect to obtain its food.

The nectar, which is the food of these butterflies and moths, is produced in the deep, hidden pockets (nectaries) of flowers. By unrolling the tongue and thrusting it down into the far recesses of the flower, the insect is able to reach the nectar and suck it up.

This long tube has been developed in the course of ages from the jaws of the creature. Each jaw is drawn out into a long threadlike body, convex on the outer surface and concave on the inner side. Together they form a tube admirably suited for their purpose and even the nectar in the very long narrow bells of sonic flowers is within reach of the long tongue.

When at rest the tongue is coiled up spirally like the mainspring of a watch, but it is always ready and can be shot out in an instant.

The adaptation of the insect to the flower also works the other way, and in the course of ages the flower has been adapting its form to the creature with the long tongue; for, while it gives up nectar to the insect, it requires a service in return. It is by these insects that the plant is pollinated to produce seeds that will carry on the race for another generation.

In seeking the nectar the insect collects pollen from the stamens of one flower, and when it goes to another flower the pollen on its body is rubbed off on the pistil, so fertilizing it.

The pretty idea in this question is just a poet’s fancy and nothing more. The truth is that we only imagine a likeness between the sound of the shell and the sound of the sea. The shell is one of those things which can pick up and make stronger certain kinds of sounds. The wooden part of the fiddle does this. If you take it away and play on the strings without it, they make a feeble, thin, unpleasant tone. The things that make sound resound are called resonators. The body of a fiddle is one, a pulpit’s sounding board is another, and a shell is another.

What the shell picks up are the very slight sounds going on all about us. It is really never quiet and the shell picks up sounds so slight that we do not hear them at all without the shell. Some scientists built a soundproof room. People inside it heard their own hearts beating. But there were cut out of the room all the tiny noises that usually go on, and when a shell was held to the ear nothing at all could be heard. The shell is only a telephone. If no sounds come to it, it is silent and can give nothing out.

The League of Nations was an association of countries intended to bring about world peace and co-operation. It was formed in 1920, following the first World War.

Although the United States did not belong to the League, the plan for it was originated by President Wilson, who thought the world was civilized enough to find some other method of settling disputes besides war. When the League was finally established the United States preferred not to join, fearing that to do so might involve the country in the affairs of foreign nations.

Beginning with forty-two nations, the membership reached its peak in 1935, with sixty. After that time membership in the League steadily declined. World War II dealt it a staggering blow; it has now become practically a dead letter. One League organization - the International Labor Office, or ILO - still carries on.

Although the League of Nations is now, so to speak, a relic of the past, it did many good things. When a dispute between Finland and Sweden threatened to destroy the peace of Europe, the League intervened. It made peace in a disagreement between Italy and Greece, and later between Bulgaria and Greece, and between Great Britain and Turkey who were quarreling about Mosul and Iraq. When the murder of King Alexander of Yugoslavia nearly provoked war between that country and Hungary, the League prevented hostilities.

It did much toward the suppression of the sale of opium; fostered better health laws; improved labor conditions, and helped rebuild the finances of various poverty-stricken countries.

Some of the most valuable work of the League before 1939 was in collecting and telling the world facts on plagues and epidemics. If customs officials knew that a certain plague was spreading in a district, they could take steps to see that the disease was not carried across the borders.

The United Nations Organization, formed at the close of World War II hopes to succeed where the League failed’, and to build a peace that will last.

The dollar, the standard unit of money in the United States, Canada, Mexico and several other countries, has a most interesting history, and so has the $ generally used to represent it.

The word dollar comes from the Low German for Thaler, which is an abbreviation of Joachimsthaler. Joachimsthal (Joachim’s dale) is a little town in Bohemia near which, in the beginning of the sixteenth century, a rich silver mine was discovered. The feudal lords of the town had coins made which, because of their excellence, were soon used all over Europe. These and similar coins were called Joachimst haters, or simply Thalers.

Coins of similar value were issued in Spain. They were called pieces of eight, because their value was divided into eight smaller coins. All these coins circulated freely in the colonies in both North and South America. In North America they were called dollars.

When the United States had been formed, the word dollar was adopted definitely for its unit of coinage, but the sign for the new coin was that of the old Spanish piece of eight. This sign showed the figure 8 (which strongly resembles the letter S), crossed by two lines representing the Pillars of Hercules, the gateway between Mediterranean and Atlantic at the southernmost tip of Spain. Thus the dollar sign really has nothing to do with the letter S, nor was it, as some people believe, originally formed by placing a narrow U over an S to form the monogram of the United States.

If we look at the map of Egypt, we shall find the Nile, which is a very good example of a river with a delta at its mouth, and we shall notice how the river, when it meets the a, spreads out into a shape something like a triangle. Now that is the shape of the Greek capital letter D, the name for which is delta; and so land of this shape and origin made at the mouth of some rivers is called a river delta.

A river consists of moving water, and the motion of the water has power to rub away m the bed and the banks of the river a large quantity of solid material. This is not melted or dissolved in the river water, but is carried down by it. Now, when the river water meets the sea, its pace slackens, because it is opposed by the weight of the sea water. The solid matter held in the river water is likely to sink and form a wide bed or bank of mud.

Deltas are nearly always found at the mouths of rivers that flow into lakes or into closed seas or sheltered gulfs, because these seas and lakes do not have strong currents or tides to carry away the solid matter. Deltas grow quite fast. The Mississippi River is depositing so much solid matter (sediment) at its mouth that the shore line is moving into the Gulf of Mexico a mile in about sixteen years.

Many factories, stores, theaters and other buildings are lighted by electrical lamps shaped as narrow tubes. The light from these tubes is soft and has almost no glare. It may be white or another color. You have heard these lamps called fluorescent lights.

The most usual electric light is a sealed bulb, or sort of bottle, filled with special gas and with a loop of fine tungsten wire. The wire is heated white hot, so that it glows, when an electric current is sent along it. We call this effect - light from heated wire - incandescent light.

Fluorescent light is quite different. There are certain metallic compounds, called phosphors, which will glow, or give out brilliant light, when exposed to ultraviolet rays. The fluorescent lamp is simply an electric arc lamp which produces the right kind of ultraviolet rays; and the tube is coated on the inside with phosphors. The ultraviolet rays strike the phosphors and they give out light.

Different phosphors give out light in different colors, so we have blue, green, white, pink, red and yellow lights. By mixing, or combining, the phosphors, it is possible to have variations of these basic colors, and even to have light that is very near the “color” of natural daylight.

The fluorescent lamp uses much less electric current, for the same degree of light, than the incandescent bulb. At the present time fluorescent lamps can not be used in the same sockets as our regular bulbs but must be used with special devices which limit the flow of current and control the operation of the lamps.

The secret of the camel’s unique value lies, as we all know, in the fact that these animals are so footed that they do not sink, as a hard-hoofed mammal sinks, into the sand. They walk on it as a reindeer walks on snow, upon a spreading, padded foot.

HOW THE CAMEL CAN MARCH FOR DAYS WITHOUT DRINKING

In addition to that, they can march for several days through the desert without drinking - though it is not true that a camel can support a huge burden through the wilds for two or three weeks at a time without any chance of drinking.

The camel is as fond of water as a thirsty human being, and it has no special way to store up the water. Like other animals water is stored in the tissues all over the body. A large amount of salt must be eaten to enable the camel to retain quantities of water without bad effects, but if plenty of salt is available a thirsty, shrunken camel will plump out amazingly.

It was once thought that the peculiar ‘cells” in the first two compartments of the camel’s stomach were used to store water, but the water contained in the stomach is not enough to do much good in the desert.

The hump, while not used to store water as such, is more important. It is almost all fat. When this fat is used up by the body, water is produced - as much as ten gallons in a large camel. In addition, the animal’s body draws upon that reservoir of fatty nourishment for the energy that it exhausts over its work and under privation.

THE ONE-HUMPED ARABIAN CAMEL IS WELL SUITED TO DESERT TRAVELING

There are two distinct species of domesticated camels in the Old World. One is the one-humped Arabian, covering a wide domain in northern and eastern Africa, Syria, Arabia and other parts of Asia Minor, and in northern India, Mongolia and south-central Asia. It is long-limbed with large spreading feet, soft for the desert sands. Callous pads, or cushions, upon its feet, and upon its chest, and on the joints of its legs protect these parts from being cut by the sharp grains of sand when the animal is walking, kneeling or lying down. Over its large dark eyes it has long eyelashes to protect it from the glaring sun and the whirling sands. Its nosrils, set slantwise above the split upper lip, can be closed also against drifting sand. That upper lip is very sensitive. Sight and smell are especially keen and the animal can tell at a great distance away where water is to be found. Its teeth are strong, just right for cropping the sparse plants of the esert. Its coat is shaggy, with a fringe of hair along the top of its neck and under its chin. The coat is colored like the sand. We know the shade as “camel’s hair.”

THE TWO-HUMPED CAMEL OF ASIA’S MOUNTAIN PASSES

The other species of domestic camel is the two-humped Bactrian camel of eastern Asia, similar to the Arabian but built more heavily, with longer, finer hair, which is dark-colored or fawn. Its feet are harder, for this camel lives, not in sandy deserts, but among the rocky wastes and mountain passes of northern and eastern Asia, in China, Siberia, Mongolia and India. It stands well the rigors of Arctic cold and of fierce heat.

No ‘wild species of camel has ever been found, but a two-humped variety is said to roam in Central Asia and Siberia. Even these animals may be only offspring of tame camels that escaped from man centuries ago. They may be runaways from dead civilization.

The long hair of the Bactrian camel is very valuable for making fine cloth. In spring the hair loosens and falls off in clumps. The hair is carefully gathered, cleaned and sorted. The fine undercoat makes the best cloth; the hairs are as fine as the finest Merino wool. Shawls of this material have been woven in central Asia for thousands of years; the best ones are nearly priceless. Nowadays camel’s-hair coats are its most common use.

THE DROMEDARY, A SWIFT CAMEL USED AS A RIDING STEED

You have heard the word dromedary. It is popularly taken to mean a one-humped camel. However, it has another, more special, meaning. Transportation camels are those which carry baggage and those trained for riding. The riding beasts are the dromedaries. They are chosen for their speed, and can go fifty to seventy-five or, occasionally, a hundred miles a day. The baggage camels are less fleet, but, going at fifteen to twenty- five miles a day, can carry five hundred to six hundred pounds. Camel caravans of 1000 animals or more are not unknown. The beasts proceed with a pacing motion, lifting the two left feet, then the two right feet, and so on. As you can imagine, the traveler must learn to ride, and at first it is not easy.

The camel’s bone is the finest thing nature has ever made for the frame of an animal. It is like ivory, dense and hard and splendid. In fact, camel bone is used in enormous quantities as a substitute for ivory. The shape of the blood corpuscles in the camels and their relatives, the llamas, is oval, like those of the birds and the reptiles, but unlike these, the camel’s red corpuscles have no nuclei. In all other mammals the blood corpuscles are circular.

We find another feature in the animal. Its temperature is not constant, like that of man and some other mammals. It rises with the surrounding heat, it falls with the drop of night’s fierce winds. We humans vary little more than a degree whether we are in the tropics or the Arctic; the camel’s temperature may rise and fall several degrees in the course of twenty-four hours. This is less change than in reptiles.

One would imagine that it must endure agonies in the noonday glare, for there is only one small patch behind the neck from which sweat glands pour out perspiration to relieve the heat of the animal’s body. However, when resting the camel actually prefers to kneel in the full glare of the sun rather than to seek shade. The rareness of sweat glands helps to conserve water.

The camel goes grumbling beneath its burden through a desert in heat. He always grumbles. He hates his master and everybody else; and many are the stories of camels trying to kill their drivers, and sometimes succeeding. Some camels are more morose and wicked than others, but they are never gentle or amiable. This is particularly true of the common burden-bearing camels. The swifter riding camel, the dromedary, is often better treated, and his disposition is not always so bad; but even he is not a gentle or affectionate beast.

There is not a moment of the day when a camel will not bite its master’s arm off if it has the chance. It can inflict one of the worst crunching nips possible by any pair of jaws. It will seize the hand that feeds it; it will take a piece out of a man’s back or leg; it will fasten upon a man who rides past it in a narrow mountain way and dash him down to death. It is possible that thousands of years of ill treatment have bred viciousness into it as fixedly as hardihood.

Even among themselves they fight dreadfully. Lacking horns, they use the teeth, and with these they seize a leg, and wrench and tug until they have thrown the rival, then they drop upon him with the knees, and pound him to death. A contest between two bull camels is a grim spectacle; and it is a dangerous one, for the example of the first two is infectious, and will set the other males roaring and battling among themselves with a fury not to be described, and a damage to merchandise not to be mentioned in the hearing of a native owner.

What would be rich abundance to a horse would not be acceptable to a camel. For him the lush grass of the meadow is not food; give him the prickly thorn, the scrubby thistle-like growth, and the camel paradise is there. One has seen a gaunt Arabian camel stride across a field ready for hay- making, and paddle through a brook, which camels abominate, to reach a hedge composed of forbidding briar and bramble, and feast with every sign of rapture.

The natural food of the animal is the ungenerous product of the desert. Where other animals would perish of starvation he waxes sleek and prosperous. The Bactrian luxuriates on bitter weeds and mineralized water, salt to the taste. It is marvelous to what ends such food can be turned. Had it been otherwise, had the camel required sustenance like that of deer and cow and antelope, human history would have been different.

We never could have crossed the deserts; the steppes would have been a barrier between Asia and Europe not to be passed. Solomon could not have built his temple at Jerusalem; the Phenicians could never have got their vares to the coasts; during the Middle Ages tea, spices, the silk and satin and gems of the East could never have come to Europe had not camels on poverty’s fare carried the burdens asked of them.

The camel serves in more ways than as a bearer of burdens. Milk from the females; flesh from the young and the old; ropes, tents, fine shawls and rugs and clothes from the hair—all these are derived from the animals. Hides and bones are also converted to human use. In time of war, a camel corps is more useful than horse cavalry in parts of Africa and India, and both British and French maintain camel units.

We shall need the camel for a long time. The desert parts of the world in which he is useful are not likely to have many railroads or motor roads soon, if indeed they are ever built, through some of the wastes. Airplane1;, to be sure, are being used in the East for long trips, but a camel can go where airplanes can not land. No other means of transportation seems likely to replace the camel soon.

Yet, for all his wondrous mastery of a melancholy, forbidding land, the camel is not a native of the place in which we find him. The story of his origin and wanderings matches all the romance of his latter- day career in domestication.

Though fossil camel forms suggest that the Arabian camel may have arisen in India, the camel tribes began in North America. Many types of camels were found in the \Vest, from the early beginnings until the coming of man.

THE FIRST CAMELS WERE ONLY ABOUT AS BIG AS FOXES

The first camels were about the size of a fox and had four toes on each foot, the side toes small and soon to disappear. From these long-extinct ancestors many kinds developed, some gazelle-like but others much larger than any still alive. The giraffe-camel was so called becnuse it had a long neck and long legs, like the giraffe, and these features enabled it to feed on the tops of the trees. just before men appeared on the scene, some of the camels went off into Asia while others wandered down the newly established bridge to South America. Then for some unknown reason the ones left behind in North America died out.

Fortunately those that picked their way along the untrodden mountains throve. They are there to this day. The South American llamas, alpacas and vicuñas are the only existing cousins of the camels.

First we have the wild vicufla, the smaller of two wild species. They are hillmen all. During the wet season of each year they keep to the higher ranges of the Cordilleras. They avoid sharp ridges and glaciers and feed in the meadows which these mountains clothe with a scanty herbage. With the coming of heat the mountain plants dry up. The vicufias then descend from the heights in search of food.

Soft-footed like the Arabian camel, they are extremely agile in the places they choose for life and liberty. Though the tribe is renowned less for sagacity than toughness, they have the wit to set sentinels to guard the feeding herds.

The guanacos are the larger, heavier species, massing in herds five hundred in number in the mountains, or reveling in the bleak discomfort of the plains of Patagonia. The llama which the ancient Peruvians domesticated was taken from the guanacos. The alpaca is the smallest, bred entirely for its woolly, hairy fleece. But the big tamed guanaco was indeed a wonder.

THE LLAMA, PACK HORSE OF THE ANCIENT PERUVIANS

For when Columbus reached America there was not a horse on all the vast twinned continent, and no animals had been tamed except the wolf, trained into a friendly dog, and, in South America, this useful beast, the llama.

The llama was the pack horse, the hackney and the beast of burden. The mysterious Peruvians had added several remarkable features to their fantastic civilization. They had learned how to grow corn, coffee, cotton and cocoa; their weaving and pottery and gold-working were of a very high order; and above all, they had captured and done with the llama what the ancient East had done with the camel. The male llamas did the work and supplied flesh food; the females were kept for their milk; and, as we have seen, the alpacas were the fleece-bearers.

THE CLEVER INCAS AND THEIR HERDS OF LLAMAS

The Incas had done as well in the breeding and perfecting of these animals for their several qualities as the old mystery men of the past had done, a thousand years before, in persuading sheep to grow flowing wool.
The alpaca’s long, fleecy coat makes finer, better wool than the llama wool. \Vool from the vicuña is the softest of all. Unfortunately it is becoming rare, and little of it reaches the market to-day.

The types that we know to-day were already fixed, high tribute to the skill of these early geniuses. It is thought that they themselves established the breed of guanaco, the one for weight-carrying and milk, the other cultivated for wool, as we have cultivated the jungle fowl for eggs. Llamas are still used to carry burdens.

Such is the story of the camel tribe. The camel has been taken about the world like cattle. It helped to carry up the wire which fenced in Australian farms from the devouring rabbit, and on the return journey it brought down wool to the ports. It toils in Zanzibar and has served in Italy; it is a valued servant in the Canaries and works for carrier and cultivator in many an odd corner of the world. Automobile and airplane have conquered the deserts, but the camels are useful still.

AN AMERICAN EXPERIMENT WITH CAMELS, WHICH FAILED

Just before the Civil War the United States Government attempted to use camels to carry supplies across the deserts of Arizona and New Mexico. The war interrupted the experiment, and many of the animals escaped For years hunters and prospectors saw them in the wilds, but it is believed that they have entirely died out.

The Jurassic period, the second great division of the Mesozoic era, receives its name from the Jura Mountains lying between France and Switzerland, a locality rich in rock formations of the period. Jurassic rocks are widely distributed throughout much of Europe, extending from the extreme north of Scotland, across England and France, to the Alps and Apennines, to Spain and northern Germany, and to central and eastern Russia. They are also found in Tibet, Kashmir, Nepal and in South Africa, New Zealand, Australia and South America.

In North America there are few Jurassic rocks. During the period most of the land in America was high above the water. In the East there are no rocks which were formed during the period, but in parts of the West where the land sank we find Jurassic rocks.

Alaska was the first land to disappear beneath the waters, and then Vancouver Island and much of California and Oregon. Later an inland sea covered most of British Columbia and much of Alberta, and extended over Montana, Idaho, Nevada, Utah and Wyoming, and a part of Colorado. This has been named the Logan Sea. In Wyoming the rocks are 3,500 feet thick. The rocks of the Jurassic in America are sandstones, shales, limestones and mans.

Towards the close of the Jurassic period parts of the world which had been under the sea began to rise. Volcanic disturbances occurred in North and South America. In North America the Pacific Mountain system was formed. Mountain ranges rose from Alaska to Mexico, among them the Sierra Nevadas.

As far as animal and plant life are concerned, there was no great gap between the Triassic and Jurassic periods. In each the plants and animals were of the same general character, although in the Jurassic there were many more species of animals. The reptiles increased so much in size and numbers that the period is often called the Age of Reptiles.

The vegetation of the Jurassic period was probably luxuriant, but not greatly varied in character. It greatly resembled that of the Triassic. Cycads and cone-bearing trees, ferns and horsetails were the most common types. The Ginkgo, or maiden-hair tree, also flourished and was the first broad-leaved tree. It still exists to-day in China and Japan, having undergone no changes for more than a hundred million years.

The animal life of the period varied greatly and is full of interest. Both land and water forms abounded; many strange forms appeared. The ammonites were the most characteristic shell-fishes of the Jurassic, although they showed signs of dying out. The belemnites, ancestors of the squids, more than held their own. There is no lack of sponges among the fossils of this period, and the remains of starfishes and molluscs are plentiful. Crinoids were common, the largest form reaching a height of fifty feet with a crown a yard long. The ancestors of the modern crab and lobster appeared. Corals were particularly abundant, and during this period most of Europe seems to have been submerged under a sea full of coral islands and coral reefs. These reefs can be traced in parts of England and from Normandy in France to the Mediterranean. They are found, too, over the east of France along the Jura Mountains and in parts of the Alps. A very different Europe it must have been, with coral reefs in England and on the mountains.

As many as a thousand species of Jurassic insects are known, including beetles, dragonflies, grasshoppers, crickets, earwigs, walking-sticks, cockroaches and termites. The social ants made their appearance in the early years of the Jurassic period. Fishes were also numerous, and sharks and rays were well represented in the seas. Most of the Paleozoic fishes about which we have already read had disappeared.

In the Triassic rocks the first mammals appeared, and in the Jurassic rocks a few more have been found. Mammals, however, were still an unimportant-seeming form of animal life. Both the European and American mammals of this early day were very much alike.

A COUNTRY GIRL DISCOVERS A THIRTY-FOOT MONSTER

The most interesting animals of the time were undoubtedly the great lizards. One of the most amazing of these was the ichthyosaurus, or fish-lizard, which originated in the Triassic and continued to develop during the Jurassic period. Certain localities in England and Germany have furnished great numbers of their remains. In a quarry at Lyme Regis, England, the first fossil ichthyosaurus was found by a country girl, Mary Anning, who made a living by collecting and selling fossils. She was hammering away at the rock one day when she noticed some big bones sticking out. When she had cleared away the rubbish and rubble round about, she found the skeleton of a huge animal and hired workmen to dig out the whole block of stone. It proved to be a monster thirty feet long, with six-foot jaws and huge eyes like saucers.

The plesiosaurus, another lizard having its origin in Triassic times, was still abundant in the Jurassic seas. However, the plesiosaurus of the Jurassic period did not reach as great a length as did his Triassic ancestor.

Crocodiles resembling the modern gavial of India swarmed in the seas and rivers. They probably spent less of their lives in the water than do their modern descendants.

PTERODACTYLS, REPTILES WITH THE POWER OF FLIGHT

Stranger in some ways, though not so monstrous, were the pterodactyls, or flying reptiles. Judging from their remains, they must have been quite common and of many different kinds. Some were as large as an albatross, and others grew no bigger than a sparrow. In appearance they were more or less bird-like. The head was usually fairly long and thin and had slender jaws equipped with curved teeth well suited for holding and tearing their prey. The bones of the forelegs, or arms, were very long and supported the leathery wing membrane. Upon the ground the pterodactyls walked about readily on their hind legs. In flight they either glided or flapped their wings just as do our modern birds.

THE FIRST TRUE BIRD MAKES ITS APPEARANCE

In the Jurassic rocks of Germany the first true bird was discovered—the Archaeopteryx. The name is Greek for “ancient wing.” Archaeopteryx was rather smaller than a modern crow. He had no beak; his jaws were lined with small, sharp teeth. His tail was longer than the rest of his body and was set with feathers on either side, giving it a fern-like appearance. In modern birds the tail is merely a stump, and the feathers spread from it like a fan. The wings of Archaeopteryx were equipped with three wing fingers. These early birds were probably better at gliding than at true flying.

Big as were the Jurassic sea lizards, there were still larger reptiles on the land. The dinosaurs which appeared in the Triassic period now attained gigantic proportions. The brontosaurus was fully sixty-five feet long and weighed about thirty-seven tons. He had a barrel-like body, at one end of which was a long, snake-like neck and at the other a slender, tapering tail. Each of his foot-prints covered about a yard. The diplodocus was still larger, reaching a length of eighty feet. The gigantosaurus, the largest land animal known, was eighty feet long, thirty-six feet of which was neck. He weighed something like forty tons.

STEGOSAURUS, A DINOSAUR CLAD IN BONY ARMOR

Not all Jurassic dinosaurs attained the tremendous proportions of the diplodocus and the gigantosaurus. Some of the most curious of them were the smaller armored reptiles which appeared quite late in the period. The strangest of these was stegosaurus. His name means “covered lizard.” Along his back ran a double row of great bony plates, which reached a height of more than two feet over his hips. Near the tip of his tail were several long spines