 Section 9 of THE SCIENCE HISTORY OF THE UNIVERSE, VOLUME 6 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Gary B. Clayton. THE SCIENCE HISTORY OF THE UNIVERSE, VOLUME 6 Edited by Francis Rolt Wheeler. Zoology, Chapter 6. The Vertebrates. Fish. The vertebrates, or backboneed animals, including fish, amphibia, reptiles, birds, and mammals, with man, are markedly differentiated in their plan of organization from the radiates, molluscs, or arthropods. This new plan of organization, leading to a higher plane of development, has made the vertebrate the dominant type of animal life, not indeed in numbers of individuals or species, as some naturalists would interpret dominance, but as individually higher types, better fitted for success and the struggle for existence. They have further opened the way in the development of man for the inception of a new era, the psychozoic era as it has been aptly called by Laconte, in which intellect becomes the principal factor in the evolution of life, controlling its environment, guiding its development, and leading to results which we can but dimly foresee, even as to those immediately before us. In a brief review of the plan of organization of the vertebrates, it will appear where when these advantages lie. In all vertebrates there is an internal skeleton, of which the central feature is the backbone, originally developed from the notochord, a segmented strip of cartilage later converted into bone, forming a nucleus of the spine. This internal skeleton, as against the external skeleton of most invertebrates, affords certain market mechanical advantages in giving the muscles a better purchase and enabling them to control the action and movements of body and limbs more powerfully. Now it is a fundamental fact of mechanics that with every doubling of the dimensions of a structure, the relative strength of its materials is reduced by one half. So that larger constructions to perform what is relatively the same work must be more massively proportioned or made of stronger material than smaller ones. This is equally true of animals. The larger an animal is, the more powerful and strongly constructed must it be in order to have the same amount of activity and obtain its proportional amount of food. It is a common saying that if a flea were the size of an elephant, he could jump over the spire of the highest cathedral in Europe. But any engineer can see the absurdity of this statement. If a flea were the size of an elephant, he would in fact be unable to lift his body off the ground. His proportionate strength would be one 4,320th of what it is and in all probability would not hold his body together. His apparent strength is merely due to his minute size. If vertebrates and invertebrates of equal size be compared, the greater strength and activity of the vertebrate is immediately perceived. Now size is a very important factor in the dominance of an animal and a superior organization of the vertebrates which has enabled them to attain much larger size is no small degree due to their having an internal skeleton. Many vertebrates have also developed for protection an external skeleton of scales or plates and the most ancient of fossil vertebrates were well armored externally while the internal skeleton was still composed of cartilage not yet hardened into bone. The nervous systems of vertebrates consist of a spinal cord along the back just above the notochord and a brain developing at the front end of the notochord. The brain is more concentrated into a single mass than in invertebrates where its functions are partly distributed among ganglia and different parts of the nervous cords. This naturally makes for more centralized and better correlated control of the different parts and organs of the body and facilitates the development of intelligence and reasoning powers. In the highest invertebrates there is a marvelous development of accurately coordinated automatic action and complexity of instinct but they seem to be unable to attain high intelligent or reasoning powers. In vertebrates while the instincts are less elaborate and complex the observer is impressed with the relatively intelligent character of their activities with their ability to respond to new sensations and accommodate themselves to new conditions of life. This is to be connected with their more concentrated brain and from the first the nervous system appears to have been more concentrated in vertebrates than in any of the invertebrate groups. All vertebrates briefed primarily by gills the water which aerated the gills entered through the mouth and making its exit through gill slits on either side of the throat. Fishes and tadpoles still breathe this way but land animals have become adapted to breathing air by means of the lungs. Rudimentary lungs are present in many primitive fishes serving to assist the gills in aerating the blood when, as in stagnant ponds the supply of oxygen in the water was not sufficient for the needs of the fish. In the more typical modern fish this rudimentary lung has been converted into the so-called swim bladder serving to adjust the weight of the body to the water around by compressing or expanding the air contained in it and perhaps for adjusting the amount and quality of air in the blood. It is interesting to observe that the embryos of all land mammals including man pass through a stage in which they possess gill slits although these serve no purpose in the life of the young animal. All vertebrates except certain very lowly types possess paired appendages fins, limbs or wings. These consist always of two pairs, never more and originate in an entirely different way from those of arthropods as folds of skins along the side of the body becoming concentrated into fins or paddles and then converted into limbs. In birds, bats and pterodactyls the four limbs are converted into wings. The alimentary or digestive system consists at first of a long straight canal near the underside of the body and is elaborated into a very complex affair by the development of various glands to assist in digestion and by the lengthening and coiling of the alimentary canal. The circulatory system is much more elaborated than in the lower animals and progressively so in the higher vertebrates. A marked difference from insects lies in the fact that air is conveyed from the lungs or gills to the tissues by medium of the blood corpuscles whereas in insects the air reaches the tissues of all parts of the body directly through the trachea. The circulation of the blood is thus a much more important function of the life of vertebrates than of insects. In the development of the skeleton it is to be noted that the spinal cord soon becomes arched over by segments of bone and the brain enclosed in a bony capsule that the underside of the body is supported by arches of cartilage from each segment of the notochord which are converted into bony ribs that the gill arches are also supported by bony arches of which the front pair is later converted into a part of the lower jaw that the teeth develop originally as scales on the skin of the mouth that the segmented limb bones retain even among mammals many suggestions of their former fin-ray construction. Various additional bones are formed in the skin of the head which coalesce with the more internal bones of brain capsule and jaw to form the solid skull of the higher vertebrates. In fishes the various bones of the head are more or less separate as also in the young of higher animals. The eyes are in general highly developed and are the most important of the sense organs. The hearing organs are also very elaborate and complicated. The sense of smell although usually highly developed has by no means the importance that it reaches among the higher insects. The vertebrates were at first and for a long time adapted to live in water. In reviewing the geological history of the different groups the successive stages of their invasion of the land and adaptation to terrestrial life will appear. Having once become well adapted to air-breathing and the more active and varied life of the dry land the vertebrates were enabled through their better plan of organization to attain larger size and higher intelligence than the insects, spiders and land snails which were their predecessors as land animals. Their internal instead of external skeleton their more concentrated nervous system and it might be added their more concentrated breathing system for the tracheae of insects may be regarded as lungs distributed throughout the whole body were probably the principal points of advantage. Vertebrates are much less ancient than the invertebrate groups. At the beginning of recorded geological history the several groups of invertebrates already were well specialized. They must have had a long previous era of evolution of which there is no record partly because the most ancient rocks containing it are so altered by crystallization that their fossils have been destroyed partly because many or all of these most ancient animals possess no hard points which could be preserved as fossils. But the earliest vertebrates appearing about the middle of the Paleozoic era are only beginning to assume the distinctive characters of vertebrata so far as can be judged from the fossil remains. They were in the dawn of their development and as they are followed upward in the geological column they are found putting on more and more of the characteristic features of vertebrata and finally at the end of the long Paleozoic era becoming adapted at first very imperfectly for active land life. The earliest vertebrates had a notochord but no bony internal skeleton but some of them had a very complete bony armor. The notochord was gradually replaced by a true backbone among the land vertebrates but more or less of it still remains in modern fishes and it was not until the beginning of the age of reptiles that it disappeared among the land vertebrates. Among these most ancient of vertebrates may be mentioned two groups the Ostracoderms covered with bony armor or sometimes with only the head armored first found in the old red sandstones of Scotland of whose quote grizzly fish in the lately flood end quote Hugh Miller has given such lively and fascinating descriptions. These animals at first glance resemble crustaceans or scorpions but they are considered as vertebrata although not true fishes. True fishes appear a little later in the primitive sharks and related types which are preserved sometimes in great perfection and the Devonian shales of Ohio and elsewhere. In the sharks and rays the internal skeleton is still composed of cartilage as it was in the primitive ancestral vertebrates. The gill slits are also of a very ancient type they consist of a number of separate slots along the outer surface of the side just behind the head. In all the higher fishes they are covered by a flap of bone and skin called the operculum or gill cover. To the bather and tropical waters to the shipwrecked seamen clinging to a raft or a float in a leaky overloaded boat the appearance of sharks is the danger most to be dreaded. Swift, powerful and voracious many of them huge in size they are the terror of the warmer seas. Indiscriminate in their appetite they are fortunately less dexterous than many other fish in seizing their prey at the surface and may often be frightened away by splashing and disturbance of the water which their low intelligence does not allow them to understand. It is probable indeed that the number of swimmers actually devoured by sharks is by no means in proportion to their reputation. The largest and most voracious of the man eating sharks is the great white shark found in all tropical seas but fortunately not very common. This species reaches a length of 30 feet and is quite capable of swallowing a man whole. It is, according to Linnaeus, the great fish which swallowed Jonah. Quote, Gessner relates that the bodies of men had been found entire in sharks a man in complete armor and over a hundred similar cases have since been recorded. Huge as is the living white shark it was far surpassed by some of its extinct relatives. The fossil shark teeth common in the phosphate beds of South Carolina and in other tertiary and Pleistocene formations are sometimes six inches long and five wide three times as large as in the largest white sharks and the animal, if of proportionate size must have attained a length of 90 feet equaling or exceeding the largest whales. It is possible that sharks of this size still exist although they have never been reported on good authority for teeth of similar dimensions have been obtained in deep sea dredging. A restoration of the jaws of this gigantic extinct shark with the original teeth all in position has recently been placed on exhibition in the Natural History Museum in New York. The gape of the jaws is nearly seven feet so that this monster could almost have swallowed a small vessel, crew and all and a traditional Jonah could easily have walked down his throat if opened for the purpose. Closely related to the white shark are the mackerel sharks, poor beagles and salmon sharks not attaining such giant size but equally swift and voracious. The high triangular back fin and the mackerel like tail are characteristic features of this group. The basking shark is the largest of the family and the largest of all true fishes attaining a length of 36 feet and an enormous bulk. Unlike its relatives it is a dull sluggish animal and does not pursue large prey. The blue sharks, tiger sharks and cub or harbor sharks are much more common and familiar than the white shark and its allies and almost equal it in swiftness and ferocity and sometimes in gigantic size. The dorsal fin is not so high and triangular and the lobes of the tail are very unequal. The upper lobe projecting far backward while the lower lobe is small. The blue shark, so commonly seen following ships and the cub shark common around the waters of tropical harbors are usually credited with the dangerous ferocity of the white shark which they hardly deserve. The rays and skates are related to the true sharks but have the body flattened out and the pectoral fins extended in a thin, continuous flap along the sides so that the animal has the shape of a flounder or halibut. They are bottom feeders living on shells and crustaceans and harmless except for the sting rays which can deliver a severe wound by a slash of the spiny tail and the torpedoes which have an electric organ capable of giving a severe benumbing shock to an enemy. The sea devils are gigantic rays the great wing-like fins expanding 20 feet. Most modern fishes have a bony internal skeleton and in various respects are higher types than the sharks. There are various partly intermediate forms between sharks and true bony fishes but their relationships need not be considered here. The perch and bass are usually considered the most typical of this group and from this type as a center they vary into an endless diversity of form structure and habit. Most of them are marine but many inhabit freshwater lakes, rivers and brooks. In the ocean they are abundant everywhere from shore to far out at sea from the surface to great depths. Nowhere are they so varied or brightly colored as around the coral reefs of tropical seas but they are equally abundant in the colder waters of the northern oceans. They form an important part of the food of all maritime peoples. The value of the herring fishery alone is $37 million annually. The most ancient type of true bony fish are the soft finned fishes allies of the herring and the trout. The herring running in immense schools in all the northern seas is more used for food than any other fish and its quote spawning and feeding grounds have determined the locations of cities end quote. Closely allied to the herring is the shad which is comprised as a food fish in the United States and the Manhattan caught chiefly for its oil and as a manure for fields. The much larger tarpon of the South Atlantic is a favorite game fish reaching a length of six feet or more and affording exciting sport to the angler. Extinct allies of the tarpon in the Cretaceous seas, Portheus reached a length of 12 feet. The trout and salmon live partly or wholly in freshwater. The salmon ascending rivers from the sea to spawn while the trout live entirely in freshwater running streams or lakes and the whitefish inhabit the great freshwater lakes of North America. The Pacific salmon enters the rivers only for spawning takes no food during its desperate struggle up to the headwaters of the stream and dies when the spawning is completed returning to the sea at the next high water. The Atlantic and European salmon much more closely related to the trout spend a much larger part of their lives in freshwater while on the other hand several species of trout descend for a time to the sea and others live partly or wholly in freshwater lakes and ponds. Salmon and trout are the chief of game fish in beauty and variety of color and delicacy of flavor in fighting qualities and in wariness they rank with any fish. If the trout and salmon are the favorites of the freshwater fishermen eels are perhaps the most heartily disliked their long, snaky form, ugly color, slimy skin and their unpleasant addiction to quote, swallowing the bait would be causes enough but in addition they are one of the worst enemies of the game fishes. The freshwater eel was long a mystery only very recently solved. The truth is that they descend to the sea to spawn reversing the habits of the salmon. The carp family includes a great many freshwater fish mostly small and less active than the salmon group. Both carp and salmon families are found only in the northern temperate regions. The carp and chubb, dace and roach minnow and shinor are familiar in our brooks and streams none of them gamey, none very good eating but passable in absence of better fish. The carp and the nearly related goldfish are natives of China domesticated there for centuries and introduced into Europe about 300 years ago. Another familiar group of freshwater fishes is the catfish family. They derive their name from the barbels or feelers around the mouth which suggests the smellers of a cat. They are not scaly but often head and parts of the body are armored with bony plates. Their special home is in South America but they are common also in northern continents and a few in Africa. They are all carnivorous gamey fish fair to good eating and most of them are found in river channels or muddy streams. Similar in habits but more graceful in form are the pike and muska lunge. The first living and freshwater streams of all the northern continents the second and the great lakes. In the South temperate zone where there are no true trout their place is taken by a distinct group of fishes of the same habits. They are the quote trout of New Zealand, Australia, Tasmania, Patagonia and the Falkland Islands and of South Africa. It has been supposed that these freshwater fish living in the isolated continents of the South and unknown in equatorial or northern regions must have spread from one to another region by way of an Antarctic continent now submerged. It has recently been found however that these fish are able to live in salt water as well as fresh so that they may have been dispersed by sea. The largest and most typical of the great groups of fish are the spiny raid fish typified by the perch and mackerel. Numerous freshwater and more abundant marine fish are included in this order. Only a few of the best known kinds can be mentioned here. The mackerel of the North Atlantic runs in great schools estimated to contain many millions of fish varying a great deal from year to year in their course. It furnishes one of the principal fisheries of New England. Larger relatives of the mackerel are the Toony, Albuquer and Bonito of the warmer seas and the Spanish mackerel of the West Indies. All these are swift, graceful, handsome fishes. The mackerel are preyed upon by their larger relative the swordfish which follows the schools to the New England coasts. Its presence is a sign that there are mackerel about. It is one of the swiftest of fishes, peaceful, compact body, forked tail and pointed head with long sword-like upper jaw are all peculiarly fitted for speed. The swordfish frequently attacks ships or boats driving its sword through a heavy plank without difficulty. The bluefish is another well-known predacious fish of the North Atlantic. It is said to be the most destructive of all fishes in the waters it inhabits. Pursuing the schools a smaller fish and killing far more than it requires for food. Professor Baird has estimated that during their stay on the New England coast the bluefish destroy upwards of 1200 million million of smaller fish. The order of perch-like fish includes a great variety of familiar fishes, freshwater and marine. The perch, bass, darters and sunfish of the still streams and lakes of the North Tempered Zone. The sea bass and their relatives, which in Australia, South America and South Africa have invaded the rivers and taken the place and name of perch. The bright-colored groups of tropical seas. The parrotfish, damselfish and angelfish of the coral reefs. The skullpins and grunards are more or less nearly related. The flatfishes are a curious off-shoot of the spring-rayed fishes. The body is very deep and narrow, both the fish swims on its side, one eye being twisted around from its normal position so that both of the eyes are on the side which lies uppermost. This side is also darker-colored than the underside. In some flatfish it is the right and others the left side which lies uppermost and shows the eyes and dark coloration. The flounders, souls, halibut, turbot and place are the best known of the flatfish. All are excellent food fishes. The codfish family. Codfish, Pollock, Haddock and its various smaller species are more remotely related to the spiny fin fishes and are of great importance as a food fish. For four centuries the banks of Newfoundland have been the chief center of the cod fishery. Among the fishing vessels all nations are represented and in succession have come Dutch, English, American and Scandinavian fishermen. End of section 9 Recording by Gary B. Clayton Section 10 of the Science History of the Universe Volume 6 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Melanie Young The Science History of the Universe Volume 6 Edited by Francis Rottweeler Zoology The vertebrates Reptiles Part 1 The frogs, toads, eths and salamanders are intermediate between aquatic and terrestrial vertebrates between fishes and reptiles. In early life they are tadpoles living in water breathing by gills having no true limbs but a fringe of fin like the median fins of many fishes. Later they undergo a metamorphosis but out true limbs with feet lose their gills and develop lungs and become adapted to live on land. They are to some extent intermediate between fishes and reptiles but are in fact much closer to reptiles if we compare the adult animals. Although fish-like in their early development there is a wide gap between them and any true fishes living or extinct. There are two living groups of amphibians the frogs and toads tailless and the eths and salamanders with long heavy tails. The eths or newts and salamanders look very like lizards but may be distinguished by their broad flat heads. They frequent damp woods and borders of ponds and may often be found by overturning stones or logs in such places. Most of them are quite small but the giant salamander of Japan, crypto branches reaches a length of five feet and the closely related hellbender is sometimes 18 inches long. The smaller eths are common in all the northern continents and a few are found in North Africa and along the Andes mountains as far south as Argentina. Some of the tailed amphibians retain their gills throughout their life especially if the conditions favor their continued aquatic life. The toads and frogs are familiar to everyone and are found in all parts of the world except in some of the oceanic islands. Toads are harmless creatures helpful to the gardener from the quantities of insects they consume, many of them curiously interesting and their mating and egg-laying habits and it is hard to see why they should be regarded with such general aversion. Like most amphibians there is a poisonous secretion in the skin which protects them from the attacks of more active animals but this is not exuded from the surface save in extremity and they can be handled with perfect safety, the poison acting only internally. There is no ground for the notion that warts on the skin are the results of handling toads. A curious myth found in early books on natural history and embalmed by Shakespeare and a quotation familiar to all credits the toad with bearing a precious jewel in its head. The frogs less poisonous than toads are protected by their greater activity and more amphibious habits. The tree toads are protected by their genius at concealment and although everyone has heard their loud trilling it is surprising how few persons have seen the little green chap with sucker like discs on the tips of the toes who is responsible for it. The modern amphibians are diminutive and specialized descendants of what was once a numerous and important race. The primitive amphibians or armored amphibians of the whole period were the first of land vertebrates and were the dominant type of land animals until the appearance of the reptiles. These armored amphibians were much like salamanders in appearance but the top of the head was solidly roofed over by bone and the underside of the body covered in scaly armor. Some of them were gigantic as compared with their modern descendants 10 or 12 feet in length with skulls 2 feet long and a foot and a half wide. From some of these ancient amphibians were probably descended the reptiles, birds and mammals of later geologic ages. The class of reptiles includes several very diverse kinds of animals, the snakes, lizards, crocodiles and turtles. Superficially they have not much in common except for the scaly skin and that they mostly lay eggs and all breathe by lungs throughout their lives. The construction of the skeleton and the various details of internal organization show that they are in fact related to each other, though not very closely. And geological history shows that they are the scattered and specialized survivors of a class of vertebrates which for countless centuries was the dominant type of land animal. The age of reptiles is estimated to have endured for some 9 millions of years. The age of mammals which followed it and culminated in the appearance of man for 3 millions of years. Compared with these vast periods, the duration of historic time shrinks into insignificance. The reptiles evolved from the primitive amphibians of the coal period and the earliest reptiles are with difficulty distinguished from them. But they were more progressive and adapting themselves to the active and varied life of the land and developed a higher and more active organization. The most important and interesting of these ancient reptiles were the dinosaurs adapted to live on dry land and taking the place in nature that was subsequently to be taken by land mammals the ordinary quadrupeds of the present day. But in addition to these there were reptiles adapted to flying and others which reinvaded the ocean and became adapted to swimming although still keeping their air breathing habit. The oldest reptiles appearing at the latter end of the coal period were clumsy heavy bodied beasts with short crooked legs like crocodiles or turtles, some of them carnivorous, others herbivorous. The most singular of these ancient reptiles were the Pelikosarians or fin-backed reptiles with an enormous rigid bony fin on the back the purpose of which and less for ornament is a standing puzzle to zoologists. The dinosaurs are perhaps most obviously distinguished as long legged reptiles for in all of them the legs are long and straight as in modern land quadrupeds instead of short and crooked as in modern reptiles. They were the characteristic land animals during the whole of the age of reptiles comprising the Triassic, Jurassic and Cretaceous periods and many of them reached a gigantic size rivaling the largest of living animals. Besides these gigantic forms there were numerous smaller, lighter, more agile kinds many of them known only by their footprints preserved in the ancient tidal flats of the Connecticut Valley and elsewhere and there is reason to believe that there were multitudes of small upland dinosaurs of which nothing is known because they never frequented the river bottoms, swamps and seashores where sediments were being deposited that might preserve the remains to the present day. Only in their modified descendants re-adapted to swamp or riverside life can be perceived the traces remaining of what must have originally been an adaptation to upland life. Most of the dinosaurs were the Brontosaurus and the Diplodocus reaching a length of 60 to 80 feet and a mass of over 30 tons in weight. These were probably amphibious animals adapted to weight in water from 20 to 50 feet in depth. They had a massive elephantine body supported on four straight rather long legs with feet very like those of elephants except for large blunt claws one on the four foot three on the hind foot which may have served to anchor the foot in slippery mud. The neck was long and flexible enabling the animal to weight to considerable depth while keeping his head above water. The tail long heavy and massive as in most reptiles. The skin was not scaly but naked, thick and heavy like that of a whale. The head is very small in proportion. The teeth adapted to tearing off soft water plants or other such material but not to chew the food nor to attack other animals. The brain is extremely small and was of low organization even for a reptile. The great mass of the nervous system being the nerves and ganglia of the spinal cord. From this it is seen that the animal was slow and unintelligent. The actions chiefly reflex and the brontosaurus may be regarded as little more than a huge automaton a vast storehouse of animal matter with but little intelligence and its movements mostly directed by reflex action. Through its aquatic life the water buoying up most of its enormous weight is able to attain a size comparable only with the modern whales and sharks. But its movements must have been slow and clumsy and on land it would be utterly helpless. It was protected from its chief enemies the carnivorous dinosaurs by being able to wade to a depth beyond their reach. Skeletons or cast of skeletons of some of these gigantic amphibious dinosaurs have recently been visited in several of the larger museums in America and Europe and are among the most impressive records of the past history of the world. The carnivorous dinosaurs were very different in appearance and habits. They were biped reptiles with long hind limbs and bird-like feet, small forelimbs, large sharp claws, short neck and large head with sharp pointed claw-edged teeth and a long lizard-like tail. Tracks of this type of dinosaur are abundant on the Connecticut sandstones and show that they usually walked or ran on the hind limbs seldom touching either forelimbs or tail. These dinosaurs lived throughout the age of reptiles both small agile species and large powerful ones. The most gigantic are the Tyrannosaurus of the late Cretaceous 40 feet in length with a skull 5 feet long and teeth projecting 4 to 6 inches from their sockets. This animal must have nearly equalled an elephant and bulk and was adapted to prey upon the huge armored dinosaurs. Other types of huge dinosaurs discovered in recent years are the armored Stegosaurs covered with bony plates and spines. The great horned seratopsians with enormous skulls defended by long sharp horns and the duck-billed Tratchodon an Iguanodon unarmored and with broad horny duck-like bill. These animals were all herbivorous and except these Stegosaurs had a fairly effective battery of grinding teeth. They reached a length of 20 to 30 feet and a bulk comparable to a hippopotamus or an elephant. They also had numerous smaller relatives, more agile and apparently more upland in their habitat. Since their skeletons are rarely found complete in the ancient sediments of the river valleys and marshes of the Age of Reptiles. Mostly they are known to science only by the scattered bones and fragments brought down by the rivers from the high-levels. The flying reptiles or pterodactyls were contemporaries of the dinosaurs and equally remarkable although less gigantic in size. These dragons of the prime had the ford limbs converted into bat-like wings by the extension of the little finger into a long slender-jointed rod supporting a membrane wing like that of bats. The tail is rudimentary and are converted into a long steering blade and the skeleton throughout is very light and fragile the bones being hollow and pneumatic, filled with air as they are in birds. Most of the pterodactyls were small from 6 inches to 3 feet expanse of wing but in the late Cretaceous appeared large forms, pteranodon, some 20 feet from tip to tip with large straight toothless beaks, adapted apparently to spearing fish. The pteranodon skeletons are found in marine formations deposited far out at sea while the small pterodactyls with shorter wings lived near the land. All of them were apparently adapted for soaring rather than fluttering and they may be regarded as nature's nearest approach to a modern airplane. In the rivers and swamps of the age of reptiles might be found crocodiles and turtles not very unlike those of the present day and a variety of extinct reptiles more or less resembling them. In the seas lived several kinds of marine reptiles some of gigantic size these, like the cetaceans seals and serenians of the present day were derived from terrestrial ancestors but had reinvaded the sea where they competed to advantage with the finny adycthones by reason of their superior organization and air-breathing habit. The plesiosaurs were long necked with compact bodies and long turtle-like flippers. The ichthiosaurs were very fish-like and outward appearance with short necks, long slender jaws and shark-like tail and were evidently adapted to swift swimming like the mackerel shark or the dolphin. The mosasaurus were more nearly related to the lizards but with flipper-like feet, large heads with powerful jaws and sharp stout teeth and long compressed tails. Some of the mesosaurs and plesiosaurs reached a length of 40 feet. The ichthiosaurs were somewhat smaller. All these great marine reptiles had become extinct by the end of the Cretaceous period and their place in the world was taken by marine mammals, ancestors of the cetaceans of our modern seas. The world must have appeared strange from a modern viewpoint during the age of reptiles. The imagination must picture dry land and swamps populated by long-legged reptiles. Many of them fantastic are in appearance and all utterly unlike any living animals. The vegetation would be less strange but its tropical aspect and the absence of many of the more abundant higher types of plants could hardly fail to impress the observer. In place of birds were the pterodactyls soaring through the air or hanging bat-like from trees or projecting rocks. Along the seashore we find many familiar invertebrates, corals, starfish, sea urchins, crustaceans and mollusks and with them swarms of nautilus-like ammonites and squid-like belomnites. Along the shores and far out at sea besides the numerous types of fishes more or less like those of the present day would be found numbers of the huge voracious marine reptiles plesiosaurs and ichthiosaurs and in the crustaceous period, mozissars rulers of the deep as the citations are today. End of Section 10 Recording by Melanie Young Section 11 of the Science History of the Universe Volume 6 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Recording by Melanie Young The Science History of the Universe Volume 6 Edited by Francis Roel Wheeler Zoology The Verdebrates Reptiles Part 2 The keynote of the age of reptiles as compared with the world of today was the dominance of brute force. The varied types of reptilia which ruled land and swamp sea and air were but little inferior in size and not greatly inferior in mechanical organization, in strength and speed to the higher animals which have taken their place. But they were notably inferior in type of brain with the intelligence adaptability and agility which it entails. Their disappearance at the end of the Cretaceous period is to be ascribed partly to their being unable to adapt themselves to changed conditions of life brought about by changes in climate and geography of the world which they inhabited. Partly to the competition of the more intelligent and adaptable mammals and birds that were being evolved to compete with them. There may have been other important factors in causing their extinction. Several have been suggested many more might be suggested. But these are known causes and must have played an important part in the process. The others are mostly guesswork. At the end of the age of reptiles there were a few surviving groups which have persisted to the present day with but little change. They were the turtles, crocodiles, lizards and snakes which on account of their habits and environment came less directly into competition with the higher quadrupeds and birds or whose surroundings were not altered by changes in geography and climate. These are the reptiles of today a small and despised remnant of a class which ruled the world for millions of years. And for a gigantic and formidable beast has hardly since been equaled. The turtles and tortoises Chalonia form a well armored group. The slow moving tortoise is one of the most thoroughly protected of four-footed animals. Give him a chance to withdraw his head, legs and tail within his shell and close the lids and no enemy can molest him unless it be large and powerful enough to crush his whole shell between its jaws. He lives upon snails, slugs, caterpillars, earthworms, etc. With a considerable addition of vegetable food, usually hibernates in winter and continues his leisurely, untroubled existence for a long period of years perhaps even for centuries. It is only in his younger days that he has much to fear from enemies. But the eggs and young are toothsome morsels for coniferous animals and in spite of the care with which the mother conceals her eggs in the sand, burying them and effacing all marks which might serve as a guide to their location, probably very few survive to be adult. Land tortoises are found everywhere except in the Australian Regent and are found on several isolated oceanic islands where, unmolested by higher quadrupeds, they are very abundant and reach large size. Their aquatic relatives to which the name turtle is usually restricted are of several different groups similar in general appearance but not very closely related. They are generally more active, less completely protected by shell and with the feet more or less completely converted into flippers for swimming. The pond tortoises or marsh turtles, terrapins, are nearest to the true land tortoises but have a flatter shell. One of the prettiest among them is the painted terrapin, Christimus with its handsome pattern of red and yellow on a background of dull greenish black but most of them are dull colored. The diamond back terrapin, noted as the finest of all edible turtles, frequents the salt marshes of the Atlantic coast especially in the southern states but is rapidly becoming scarce except where artificially protected. The snapping turtles and mud turtles are more aquatic and less completely protected by bony shell. The sea turtles are wholly marine, mostly confined to tropical seas and valued not only as food but for the tortoise shell manufactured from the outer layer of the carapace. The largest of these marine turtles is the green turtle chelone, inevitably connected in song and story with aldermanic banquets and other such civic functions. A near relative is the hawksbill turtle the chief source of the tortoise shell of commerce. The side-necked turtles, abundant in the rivers of all the southern continents are rather distantly related to those we have mentioned. Although much alike superficially the construction of the carapace is different and in withdrawing the head into the shell they bend the neck sideways while the others bend it vertically in an S-shaped curve. Vast numbers of these turtles live in the South American rivers. The soft-shelled river turtles, Trionix of the northern continents on the one hand and the marine leathery turtles on the other are ancient offshoots of the main chelonian stock which have endured with little change since a reptilian age. Like the turtles the crocodiles are a race of ancient lineage. During the age of reptiles they infested both seas and rivers in all parts of the world. Since then their range has been gradually restricted. The marine forms long ago became extinct. The river crocodiles have disappeared from most temperate regions and are common only in tropical or subtropical rivers. The living species are grouped as alligators, crocodiles and gavels differing in the width of the skull and to some extent in their food habits. The narrow-snouted gavels of the East Indies feed chiefly upon fish. The broad-headed alligators, chiefly New World and the crocodiles chiefly Old World with heads of medium width and muzzles notched at the sides near the front to receive a large tooth in the lower jaw. These are land animals which come down to the rivers to drink or attempt to cross. These also live partly on fish. They are said to dig burrows in the banks of the rivers where they dwell and like turtles they lay their eggs in a nest in the dry sand or earth of the river bank, usually covering them up and leaving them to hatch by the heat of the sun. The crocodile with its lower scales, its powerful jaws and tail is still formidable in modern tropical rivers and to primitive man armed only with spears and arrows it must have been almost unassailable. One cannot wonder at the superstitious respect in which it was held in ancient Egypt. The caimans of South America are closely related to the alligators. In contrast with the slow moving armor turtles and crocodiles the lizards are mostly quick active small in size and unprotected by armor the skin covered with small horny scales. They are wholly terrestrial most abundant in arid or desert regions but they live almost everywhere except in the cold temperate and arctic zones. Their small size, quick movements dexterity and hiding ability to live in rocky and desert places enable them to compete very well with small mammals and they are a numerous and varied race. For the most part they live upon insects and are very adept in catching them. A few lizards attain a considerable size. The monitors of Africa the East Indies and Australia reach a length of 6 or 7 feet in the tropical parts of the new world the iguanas of size. Among the smaller kinds the geckos, skinks and true lizards are most familiar. Professor Gatto describes the habits of the gecko as follows In their native haunts they are very regular in their habits. Favorite resorts of theirs are old olive trees or oak trees in the rough and cracked bark of which affords excellent places for hiding in. Not a single specimen is seen during the early hours of the morning or in the forenoon but when the sun has become broiling hot and our own shadow passes over the stem of a tree we become aware of flitting little shadows which jerk over its surface. These are geckos which had been basking, motionless, very dark grey almost blackish just like the color of the greybark upon which the last season's wet moss has been scorched to a black cinder. It is difficult to aspire a gecko while it is glued on to such a tree only the little beady eyes betray it watching you carefully. Nothing appears more easy than to catch that motionless thing. You put out your hand and it is gone like a flash it has moved a foot higher up or down to the right or to the left just where you least expected it to go seems motionless as before. It does not seem to run it glides along dodging over to the other side of the stem and back again. There is system in its motions since taking a last leisurely look around it gently disappears in a rent or whole. Toward the evening or when these shadows become longer the geckos become lively. One after another appears on the surface upon the tree or at the entrance of the cave and they all move about in their peculiar rushing jerks. Spiders, flies, mosquitoes, moths form the principal diet and the hunting goes on well into the night. Where a gecko has been seen once it is sure to reappear the next day at the same hour. Those which take up their abode inside a house become almost domesticated. They are strange sights when hunting for flies running up and down the papered walls. But we fairly gasp when they come to the upper corner calmly bend over and with the next jerk slide along the whitewashed ceiling. We are accustomed to flies performing such feats but at animals five inches long supple and fat we are inclined to draw the line. However that is the way of geckos and be it confessed the more we ponder over the mechanism of their fingers and toes we comprehend how such little vacuums can support or suspend such heavy creatures from a dry and often porous surface. Among the 1500 species of true lizards many are a very odd appearance and interesting habits. The flying dragons of the East Indies have wing like membranes shaped very like the wings of a butterfly when extended supported by long extensions of the rims and used parachutes in long leaps from tree to tree. They are not much larger than a large butterfly so that the named dragon is rather a misfit as to size. Another remarkable type is the Plamedosaurus or frilled lizard of Australia with very long slender legs and tail and a large frill around the neck which it erects when brought to bay. It runs ordinarily on its hind legs, the four legs hanging down, the long tail balancing the body. In shape the frill has an absurd resemblance to the great bony neck frills of the horned dinosaurs and the long legs and biped gate are also singularly like certain dinosaurs. It is said to reach a length of two or three feet. The quaint little horned toads, Phrynosoma of the western United States too suggest some of the extinct armored dinosaurs. The ugly, poisonous Gila monsters of the same region brightly colored in orange and black are a well known example of warning coloration the colors enabling the hungry bird or coyote to recognize and avoid them. The chameleons are found chiefly in Africa although they range into Spain and India as well. They are very odd and interesting little lizards and their habits and their color changes have been carefully watched and studied. The head is high and narrow the body compressed sideways unlike most lizards and the feet are very peculiar two toes in each foot being opposed to the other three. The tongue is very peculiarly constructed and the club shaped sticky tip can be shot out suddenly to a distance of seven or eight inches annexing the insect which the chameleon is stalking. They are extremely slow and cautious in their movements. The changes in color are only partly protective chiefly related to the excitement or chiescence of the animal or to heat and cold as was long ago stated by Linnaeus. Some of the Madagascar chameleons reach a length of two feet mostly only a few inches long. No reptiles are so familiar and yet so much maligned as snakes. Most people regard a snake with horror or at least with strong aversion. It is nasty, slimy, venomous it kills chickens it fascinates and devours little songbirds and its bite is deadly poison to man. They think to be killed on sight but from a good distance and with stones or sticks lest it attack you. Almost every small boy in the great majority of grown folk will kill any snake they see feeling that it is the natural and proper thing to do. As a matter of fact snakes are not at all slimy their skin is perfectly dry and scaly they are quite as clean to handle as a dog or cat. There are a few poisonous snakes but one may readily learn to recognize and avoid them. Most snakes, except in Australia are perfectly harmless and are a great help to the farmer as they devour quantities of mice and insects. Snakes do not fascinate birds the fluttering apparently helpless bird is simply trying its best to entice the snake away from its nest. A snake, poisonous or non-poisonous will pursue a human being. Their chief anxiety if they see one is to get away as quickly as they can to a place of safety. When cornered or suddenly disturbed without a chance to escape they will hiss and strike with the fore part of the body. A snake's striking distance is from a third to a half its length but all this demonstration is entirely harmless unless the snake is a poisonous one and strikes some part of the body where its fangs can get through the clothing to the skin. For all the popular fear of snakes actual recorded cases of death from the bite of a poisonous snake in the United States are extremely rare. In India and in other tropical countries the case is different. The mortality from snake bite is large partly because venomous serpents are more common chiefly because the natives habitually travel barefoot through the jungle. The deaths from snake bite in India are officially estimated at 22,000 a year about 1 in 15,000 of the population. It is probably less in other tropical regions. It is commonly said that poisonous snakes may be distinguished by their broad flat heads from the non-poisonous kinds. This is only partly true. The poisonous snakes of the viper family including the viper, puff adder, copperhead, water moccasin, fur dilants and rattlesnake do have wide short heads so do several kinds of non-poisonous snakes. But in the coral snakes and cobras the deadliest of all venomous serpents the head is of the same shape as the common harmless garter snake or black snake. Snakes are the most highly specialized of the reptilia. Although undoubtedly descended from four-legged walking reptiles, no traces of limbs remain except for some vestiges in the boa and python. The body is much elongated and adapted to crawling. The peculiar loosely hung double-jointed jaws and the very elastic throat and neck admit of extraordinary stretching so as to swallow the prey whole so that the snake literally gets outside of his victim by alternately setting forward the upper and lower jaws with their sharp little recurved teeth. The poisonous snakes have one pair of teeth in the front of the jaw enlarged and provided with a groove or canal through which the poison is injected into the wound. In the cobras and coral snakes the poison fangs are fixed and the vipers they lie back against the roof of the mouth in repose and are erected only when the snake opens its mouth to strike. The great majority of the species live on dry land hiding at night and in cold countries hibernating through the winter and crevices among rocks in burrows made by rodents or any other convenient shelter. Many snakes live partly or wholly in freshwater streams or ponds a few are marine some species lay eggs others bring forth their young alive. The largest snakes are the boas and pythons of tropical countries which are said to reach a length sometimes of 30 feet and kill their prey by crushing it between their coils whence the name constrictor 9 tenths of the living species of snakes belong to the harmless colubrine group of which the pretty striped garter snakes are the most familiar kind the black snakes, bull snakes and hog-nosed snakes are well known in North America many others under various names take their place in other continents. Some of these colubrine snakes constrict their prey swallow it without the formality of previously killing it. Related to the colubrine snakes are the cobras of the old world and coral snakes of the new all-tropical or subtropical and the most deadly of poisonous serpents. The majority of Australian snakes belong to this venomous group so that in Australia the popular fear and hatred of snakes is justified more than in other continents. The peculiar habit of cobras when angered and ready to strike of expanding the skin of the neck into a broad, brightly marked hood may be compared with the rattle of a rattlesnake and is usually supposed to serve as a warning signal serving notice upon approaching large animals that a poisonous snake is at hand to be carefully avoided and not carelessly stepped upon or eaten. Some perfectly harmless snakes have the custom when one comes close to them of rattling the tip of the tail among the dry leaves in a way that makes a fair imitation of a singing rattlesnake. This quivering of the tail may be probably is simply from excitement. Nevertheless it may serve to scare off large animals of inquisitive disposition and so be useful to the snake. The snakes of the viper family are all poisonous and inhabit both temperate and tropical regions. They include the vipers and puff adders of Europe, Asia and Africa, the moccasin copperhead and rattlesnake of North America, and the palm vipers and fair delants of tropical America and the West Indies. All are very poisonous although not quite so deadly as the cobra group. The virulence of the poison differs with the size and the condition of the snake as well as with the species and with the size and stamina of the animal or person bitten. The bite of the fair delants has the reputation of being most generally fatal to man. And of Section 11 Recording by Melanie Young Section 12 of the Science History of the Universe, Volume 6 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Recording by Gary B. Clayton The Science History of the Universe, Volume 6 Edited by Francis Rolt Wheeler Zoology Chapter 8 The Vertebrates, Birds Birds as a class are the most attractive of animals. In intelligence in restless activity in compact graceful form in handsome colors and markings in musical voices they equal or surpass any others. Although egg laying like the lower vertebrates they give far more care and attention to the incubating of the eggs and the rearing of the young. Family life is well developed among them whereas among the lower vertebrates can be found only some scarcely recognizable beginnings of it. It is easy to understand and appreciate the actions and sensations of a bird where those of an ant are strange and foreign to the mental attitude of the human. Birds too are peculiarly the friends of man and his relations to the world of nature. They are the great natural check upon the multiplication of his insect enemies. It has been said if it were not for birds the world would be so overrun with insects that all crops would be destroyed. Successful farming would be impossible and in consequence civilized man could no longer maintain his existence. This assertion greatly overrates their importance to civilization and regarding them as indispensable to its continued existence. Besides the birds there are other important natural checks upon the indefinite multiplication of noxious insects aside from the artificial checks devised by man or which would be devised if the need for them were sufficiently urgent. Yet the services rendered by birds to the farmer are truly of immense value far out balancing the occasional toll taken from his seed corn or his chicken yard even by those birds most generally counted as his enemies. A bird says Godot quote may be known by its feathers end quote for all birds have feathers and no other animal possesses them. In other ways they form the most compact and readily distinguishable of the four groups of land vertebrates. They are all surprisingly alike in construction of skeleton and in the anatomy of the soft parts. With all their wide diversity in size and form and habits of life it is singularly difficult to distinguish the bones of the different groups. The reason for this would seem to be that successful flight in an animal as large as a bird involves a high degree of specialization and mechanical perfection of skeleton and muscles and limits the variations that may occur within rather narrow lines. The wide diversity of form and structure that exists among the mammals is not here found yet birds are an equally ancient group and have had ample time to assume diversity of form in relation to their diversity of habits hardly less than that of terrestrial quadropods. On the other hand they show much more variety and brilliancy of color. The high degree of specialization of birds appears throughout their organization. The forelimbs are modified to serve as wings. The neck is long the tail short and rudimentary so far as the skeleton is concerned. The heart is four chambered and the circulation rapid and strong. The body is kept constantly at a temperature of 100 degrees instead of being only slightly higher than the temperature of the surrounding medium as it is in the quote cold-blooded end quote vertebrates. The lungs are large and respiration is further aided by air sacs which expand from the bronchial tubes into parts of the body cavity and the hollow bones. The muscles, as in mammals are more distinct and sharply defined than in the lower vertebrates. The brain is of much higher type than in reptiles and is comparable to the mammalian brain. All in all the birds represent a development of the vertebrate stock ranking the mammals as the highest type of animals inferior in certain phases of intelligence but superior perhaps in activity and perfection of mechanism. The feathers of a bird serve two essential purposes. In the first place they are bad conductors of heat and prevent the body heat from escaping just as does the hair of mammals. Thus the bird and mammal are unable to maintain a high bodily temperature impossible to scale or naked skinned reptiles amphibians and fish. The high bodily temperature and rapid circulation are essential to the higher development and more active life of bird and mammal. The second essential purpose of the feathers is to aid in flight. While flight can be accomplished as it is in bats or insects and was in pterodactyls without the aid of feathers yet they furnish the most effective mechanism the feather has devised for perfect control of movement in the air with animals as large as birds. The classification of birds is a most difficult problem. The older arrangements according to habits and external characters do not altogether agree with the natural relationships of different groups. It is nevertheless very convenient and the division into perches, waders, birds of prey, marine birds, ostriches, etc. although known to be unnatural is largely used in default of general agreement as to the natural relationships of the different groups. It may be assumed that birds are derived from some early type of primitive reptile nearly related to the dinosaurs in the early part of the age of reptiles. This hypothetical ancestor of the bird would be distinguished from the small upland dinosaurs mainly by the fact that its scales had evolved into feathers thereby enabling it to maintain a higher body temperature and more active life. Its habits would be much like those of the ostriches but the tail long, vertebrated, lizard-like with feathers on each side and the jaws provided with teeth instead of a horny beak. The transformation of the forelimbs into wings might result either from their being used as an aid to running on the ground or in making soaring leaves from tree to tree. The second explanation is generally regarded as most probable. The oldest known fossil bird, the archaeopteryx of the Jurassic period middle part of the age of reptiles appears to be in this transitional stage. It was about the size of a crow and had the toothed jaws and long vertebrated tail of a reptile feathered like the shaft of an arrow. Its wings were short and small and in the opinion of some authors at least could hardly have served for true flight but might enable it to flutter from bow to bow. The remains of a few birds of the Cretaceous period have been found. The two best known are the Hesperornus and Ictheornus both provided with teeth but the tail is of the usual bird type. Hesperornus was a marine diver allied to the loons and grebes and fully as large but more primitive in various details of the skeleton. Ictheornus was a flying bird allied to the galls. These three genera archaeopterus, Hesperornus and Ictheornus are the most important fossil birds as regards the evidence they offer toward the problem of the course of evolution of the birds and the relations of the various modern orders. They are a long way however from clearing up the problem. Most of the remaining fossil birds are very imperfectly known and a remarkably large proportion of the more familiar kinds are large flightless ground birds. This does not mean as might be thought that ground birds were formerly more abundant than now but rather that on account of their size and habits their bones are more likely to be preserved and noticed by collectors than those of the smaller, fragile bound flying birds. All that can be concluded as to the early evolution of the class is that they were derived from long legged bipedal reptiles probably inhabiting the upland regions of the great land mass of the northern continents. That they develop feathers from scales primarily for warmth, secondarily for flight, that they subsequently lost their tails and later on their teeth but that at a very early moment in their evolution they had become differentiated into various habits perching, running, diving, soaring. Since the center of dispersal of their early evolution was the upland regions of the north it is reasonable to expect to find the highest and most typical birds in that general habitat. Remnants of primitive bird races, archaic survivals we should expect to find in the most remote southern regions or among marines or diving birds or especially among the flightless ground birds. To a certain extent these expectations are carried out but the birds are a race of ancient development and their strong and sustained flight gives them great powers of distribution over distances and across barriers that impede or baffle the migration of terrestrial animals. The bird life therefore of southern continents and tropical islands is much less peculiar and archaic than the mammalian life. The very primitive races have long ago been swept out of existence by competition with more progressive invaders. The apparently primitive survivals such as the ground birds which today inhabit Australia, South Africa and South America and others which have become extinct such as the penguins of the Antarctic region, the loons and grebes of northern lakes, the ox and other apparently primitive types all these must be regarded not as true primitive survivals but as cases of at least partial reversion of re-adaptation to ancestral habits from various stocks of more progressive and typical flying birds where the conditions of their environment favored the development of types of birds similar in habits to early ancestors of the bird class. The ostriches distinguish from all other ground birds by having only two toes. It is native to the African continent but has been introduced in other arid regions with success and is the largest of living birds. A full grown male stands over eight feet high and can outrun a horse. The handsome tail feathers have long been used for ornament and the value of the annual output in South Africa is estimated at five million years, mostly derived from the large ostrich farms where the birds are semi-domesticated. The ria of southern South America, the emus and cassowaries of Australasia and the kiwi of New Zealand are similar in habits to the ostrich but of smaller size and with toes of the normal bird type. Among the extinct flightless birds the moas which inhabited New Zealand in quite recent geologic times were related to the kiwi but reached a much larger size than the ostrich, the largest being estimated at 12 feet in height. The extermination of these birds by the Maori natives dates not more than four centuries ago. Equally recent is the disappearance of the great Apornus of Madagascar upon which it is said the eastern legends of the rock are founded. The rock as it is described in the Arabian Nights is exaggerated and distorted into a flying bird of impossibly gigantic size but it may have been founded upon the eggs of these great ground birds, some of which are still in existence and large enough to hold two gallons of liquid. These great flightless birds are usually grouped into a subclass, retaiti although they are very probably degenerate descendants of several stocks of flying birds. There are other large extinct flightless birds in which the relationship to different groups of flying birds is more clearly seen. Such are the dodo and solitaire of Mauritius related to the pigeon and exterminated only two centuries ago. The fororachos of the Mayocene epic in Patagonia related to the modern Sarriima or Crested Screamer, the gastornus of the European Eocene related to the ducks. The most primitive or degenerate of marine birds are the penguins of the Antarctic regions, flightless, active swimmers and divers with the wings modified into paddles. In penguins, the three metatarsal bones of the hind foot are partially separate, more primitive than in any other bird. They are known to have inhabited the Antarctic seas at least as far back as the early tertiary and are probably a very ancient group. If future explorations succeed in discovering fossil remains of the fauna which inhabited the old Antarctic continent during the age of mammals, it is very probable in the present writer's opinion that its higher land vertebrates will prove to have been not mammals but great ground birds of which the modern penguins are a solitary marine survival. The divers and grebes are the most primitive of the modern flying birds. Aquatic or marine in their habits they are mostly heavy and awkward in flight or on land, but excellent swimmers and divers using the webbed or lobed feet very effectively in swimming. The divers are arctic, the grebes, cosmopolitan and distribution. The petrals and albatrosses and their allies are strong flying ocean birds worldwide and distribution, but most abundant in the desolate wastes of the southern oceans. Beyond all other birds they are at home on the ocean resting and sleeping on the surface of the waves resorting to land only for breeding purposes and nesting on the rocky ledges of wild inaccessible sea cliffs. A much larger group of water birds is represented by the storks and their allies mostly wading birds inhabiting water but some marine like the tropic birds, ganets, cormorants and frigate birds. The storks, ibises, herons and bitterns, the flamingos and pelicans are the most familiar wading types various in size and proportions in habitat and nesting habits feeding upon fish, frogs and other denizens of the marshes and rivers. Many of the birds of this group are distinguished in size, handsome colors and decorative plumes. The ducks and geese are a still more familiar group of birds, aquatic in their habits and mostly fresh water dwellers but swimming and diving rather than wading, more omnivorous in their feeding habits than the wading birds. They are cosmopolitan but most abundant in the northern continents. The domesticated species are of large economic importance and the wild species form a considerable proportion of the common game birds. The eagles, hawks and vultures are widely different in appearance and habits from the preceding groups. They constitute the birds of prey, excluding the owls and are all carnivorous mostly predacious living on land and preying upon smaller birds and mammals or upon carrion, sometimes upon fish, occasionally upon insects. In accordance with their habits they are swift and powerful in their flight the bill is adapted to seize and tear their prey the claws are sharp, strong and curved. The condor of the Andes is one of the largest of flying birds. While to some extent eagles and hawks merit the hostility of man by their slaughter of smaller birds their depredations upon the poultry yard and their occasional attacks on larger domestic animals yet most of the hawks at least prey largely or chiefly upon rodents and, with the owls are an important natural check upon their increase. As a class they undoubtedly do far more good than harm to the farmer and their persecution is often followed by a terrifying increase in the numbers of noxious rodents. The domestic fowl and their allies are the most familiar of birds and the most important economically. To this order belong besides the domestic fowl peacock, turkeys and guinea fowl the pheasants, partridges grouse and quail the carousels and howtson of South America and many less known birds. In the pheasant group are included the greater number of game birds. The birds of this order are generally polygamous and the majority handsomely colored especially the males. The rails, cranes and bustards are a second waiting group similar in habits to the storks and their allies but not closely related. Another order of very varied habits is formed by the plover, sandpipers and curlews, the gulls and awks and the pigeons very diverse and outward form but connected by common characters and the skeleton. The cuckoos and the parrot family comprising the parrots parakeets, macaws and cockatoos are distinguished by having two of the toes reversed instead of one as in most other birds and a special adaption for climbing and grasping branches. A much larger order includes the night jars, swifts and hummingbirds, the owls kingfishers and woodpeckers the trojans, toucans, hornbills and various other more or less familiar birds. They are all land birds of arboreal habits with short legs, the majority nesting in holes and trees are similar places and the young are born blind and peculiarly helpless. Their feeding habits are various, the owls being predacious, pursuing small mammals and birds and mostly nocturnal. The kingfishers feed upon fish the woodpeckers especially upon boring beetles, the swifts and night jars upon insects the hummingbirds upon the nectar of flowers, while the large toucans and hornbills are mainly fruit eaters. The owls by their destruction of noxious rodents, render aid to the farmer that far more than counter balances the toll they levy on his chickens. By far the largest order of birds is the pesseriformis including the songbirds and their allies. It contains some 5500 species, more than half the whole class. To this great order belong all the true singing birds besides many which do not sing. They are mostly of small size of high intelligence as shown in their habits their nest building and in the care of their young. They are all land birds terrestrial or arboreal in their nest building the feet adapted for perching with one reverse digit and three in normal position their powers of flight moderate or highly developed. A large proportion of them are seasonal migrants traveling thousands of miles in their annual flights. They inhabit every region of the world continents and islands. They range from sea coast swamps to above the snow line in the mountains forest, plain and desert all have their special types of songbirds adapted in habits and plumage to the requirements of their surroundings. There are numbers and variety or immense and even enlarged on the theological books their mere enumeration is lengthy and cumbersome. End of section 12 recording by Gary B. Clayton