 PREFACE OF DRAGONS OF THE AIR I was a student of law at a time when Sir Richard Owen was lecturing on extinct fossil reptiles. The skill of the great master, who built bones together as a child builds with a box of bricks, taught me that the laws which determined the forms of animals were less understood at that time than the laws which govern the relations of men in their country. The laws of nature promised a better return of new knowledge for reasonable study. A lecture on flying reptiles determined me to attempt to fathom the mysteries which gave new types of life to the earth and afterwards took them away. Thus I became the very humble servant of the dragons of the air. Knowing but little about them I went to Cambridge and for ten years worked with the Professor of Geology, the late Reverend Adam Sedgwick, LLD, FRS, in gathering their bones from the so-called Cambridge Copperlite Bed, the Cambridge Greensand. The bones came in thousands, battered and broken, but instructive as better materials might not have been. My rooms became filled with remains of existing birds, lizards and mammals which threw light on the astonishing collection of old bones which I assisted in bringing together for the university. In time I had something to say about flying animals which was new. The story was told in the Theatre of the Royal Institution in a series of lectures. Some of them were repeated in several English towns. There was still much to learn of foreign forms of flying animals, but at last with the aid of the Government Grant administered by the Royal Society and the Chiefs of the Great Continental Museums I saw all the specimens in Europe. So I have again written out my lectures with the aid of the latest discoveries and the story of animal structure has lost nothing in interest as a twice told tale. It still presents in epitome the story of life on the earth. He who understands whence the flying reptiles came, how they endured, and disappeared from the earth has solved some of the greatest mysteries of life. I have only contributed something towards solving the problems. In telling my story, chiefly of facts in nature, an attempt is made to show how a naturalist does his work in the hope that perhaps a few readers will find happiness in following the workings of the laws of life. Such an illumination has proved to many worth seeking, a solid return for labour, which is not to be marketed on the exchange, but may be taken freely without exhausting the treasury of nature's truths. Such outlines of knowledge as here are offered to a larger public may also, I believe, be acceptable to students of science and scientific men. The drawings given in illustration of the text have been made for me by Miss E.B. Sealy, H.G.S. Kensington, May 1901. End of Preface, Chapter 1 of Dragons of the Air. 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 Jeffrey Smith, New Orleans, Louisiana. Dragons of the Air by Harry Sealy. Chapter 1. Flying Reptiles. The history of life on the earth during the epics of geological time unfolds no more wonderful discovery among types of animals which have become extinct, then the family of fossils known as flying reptiles. It's coming into existence, its structure, and passing away from the living world are among the great mysteries of nature. The animals are astonishing in their plan of construction. In aspect, they are unlike birds and beasts which in this age hover over land and sea. They gather into themselves in the body of a single individual, structures which at the present day are among the most distinctive characters of certain mammals, birds, and reptiles. The name Flying Reptile expresses this anomaly. Its invention is due to the genius of the great French naturalist Cuvier, who was the first to realize that this extinct animal, entombed in slabs of stone, is one of the wonders of the world. The word Reptile has impressed the imagination with unpleasant sound, even when the habits of the animals it indicates are unknown. It is familiarly associated with life which is reputed venomous and is creeping in cold. Its common type, the serpent, in many parts of the world takes a yearly toll of victims from man and beast, and has become the representative of silent active strength, dreaded craft, and danger. Science uses the word Reptile in a more exact way to define the assemblage of cold blooded animals which in familiar description are separately named serpents, lizards, turtles, hatteria, and crocodiles. Turtles and the rest of them survive from great geological antiquity. They present from age to age diversity of aspect and habit, and in unexpected differences of outward proportion of the body show how the laws of life have preserved each animal tight. For the vital organs which constitute each animal a Reptile, and the distinctive bony structures with which they are associated remain unaffected or but little modified by the animal's external change in appearance. The creeping Reptile is commonly imagined as the antithesis of the bird. For the bird overcomes the forces that hold even man to the earth and enjoys exalted aerial conditions of life. Therefore the marvel is shared equally by learned and unlearned, that the power of flight should have been an endowment of animals sprung from the breed of serpents or crocodiles, enabling them to move through the air as though they too were of a heaven-born race. The wonder would not be lessened if the animal were a degraded representative of a nobler type, or if it should be demonstrated that even beasts have advanced in the battle of life. The winged Reptile, when compared with a bird, is not less astounding than the poetic conceptions in Milton's Paradise Lost of degradation which overtakes life that once was amongst the highest. And on the other hand, from the point of view of the teaching of Darwin in the theories of modern science, we are led to ask whether a flying Reptile may not be evidence of the physical exaltation which raises animals in the scale of organization. The dominance upon the earth of flying Reptiles during the great middle period of geological history will long engage the interest of those who can realize the complexity of its structure, or care to unravel the meaning of the procession of animal forms in successive geological ages which preceded the coming of man. The outer vesture of an animal counts for little in estimating the value of ties which bind orders of animals together, which are included in the larger classes of life. The kindred relationship which makes the snake of the same class as the tortoise is determined by the soft vital organs, brain, heart, lungs, which are the essentials of an animal's existence and control its way of life. The wonder which science weaves into the meaning of the word Reptile, bird, or mammal is partly in exhibiting minor changes of character in those organs and other soft parts, but far more in showing that while they endure unchanged the hard parts of the skeleton are modified in many ways. For the bones of the Reptile orders stretch their affinities in one direction towards the skeletons of salamanders and fishes, and extend them also at the same time in other directions towards birds and mammals. This mystery we may hope to partly unravel. Jeffrey Smith. New Orleans, Louisiana. Dragons of the Air by Harry Seeley. Chapter 2. How a Reptile is Known. Definition of Reptiles by Their Vital Organs The relations of reptiles to other animals may be stated so as to make evident the characters and affinities which bind them together. Early in the nineteenth century naturalists included with the Reptilia the tribe of salamanders and frogs which are named Amphibia. The two groups have been separated from each other because the young of Amphibia pass through a tadpole stage of development. They then breathe by gills like fishes, taking oxygen from the air which is suspended in water before lungs are acquired which afterwards enable the animals to take oxygen directly from the air. The Amphibian sometimes sheds the gills and leaves the water to live on land. Sometimes gills and lungs are retained through life in the same individual. This Amphibian condition of lung and gill being present at the same time is paralleled by a few fishes which still exist like the Australian Ceratidus, the lungfish, an ancient type of fish which belongs to early days in geological time. This metamorphosis has been held to separate the Amphibian type from the reptile because no existing reptile develops gills or undergoes a metamorphosis. Yet the character may not be more important as a ground for classification than the community of gills and lungs in the fish and Amphibian is ground for putting them together in one natural group. For although no gills are found in reptiles, birds, or mammals, the embryo of each in an early stage of development appears to possess gill arches and gill clefs between them through which gills might have been developed even in the higher vertebrates if the conditions of life had been favorable to such modification of structure. In their bones, reptiles and amphibia have much in common. Nearly all true reptiles lay eggs which are defined like those of birds by comparatively large size and are contained in shells. This condition is not unusual in Amphibians or fishes. When hatched, the young reptile is completely formed, the image of its parent, and has no need to grow a covering to its skin like some birds, or shed its tail like some tadpoles. The reptile is like the bird in freedom from important changes of form after the egg is hatched, and the only structure shed by both is the little horn upon the nose with which the embryo breaks the shell and emerges a reptile or a bird growing to maturity with small subsequent variations in the proportions of the body, the reptile skin. Between one class of animals and another, the differences in the condition of the skin are more or less distinctive. In a few Amphibians there are some bones in the skin on the underside of the body, though the skin is usually naked, and in frogs is said to transmit air to the blood, so as to exercise a respiratory function of a minor kind. This naked condition, so unlike the armored skin of the true reptilia, appears to have been paralleled by a number of extinct groups of fossils of the secondary rocks, such as ichthyosaurs and plesiosaurs, which were aquatic and probably also by some dinosauria, which were terrestrial. Living reptiles are usually defended with some kind of protection to the skin. Among snakes and lizards the skin has commonly a covering of overlapping scales, usually of horny or bony texture. The tortoise and turtle tribe shut up the animal in a true box of bone, which is cased with an armor of horny plates. Crocodiles have a thick skin embedding a less continuous coat of mail. Thus the skin of a reptile does not at first suggest anything which might become an organ of flight, and its dermal appendages or scales may seem further removed from the feathers which ensure flying powers to the bird than from the naked skin of a frog. The reptile brain Although the mode of development of the young and the covering of the skin are conspicuous among important characters by which animals are classified, the brain is an organ of some importance although of greater weight in the higher vertebrata than in its lower groups. Reptiles have links in the mode of arrangement of the parts of their brains with fishes and amphibians. The regions of that organ are commonly arranged in pairs of nervous masses, known as one, the olfactory lobes, two, the cerebrum, behind which is the minut pineal body, followed by three, the pair of optic lobes, and hinder most of all, four, the single mass termed the cerebellum. These parts of the brain are extended in longitudinal order, one behind the other in all three groups. The olfactory lobes of the brain in fishes may be as large as the cerebrum, but among reptiles and amphibians they are relatively smaller, and they assume more of the condition found in mammals like the hare or mole being altogether subordinate in size. And the cerebromasses begin to be wider and higher than the other parts of the brain, though they do not extend forward above the olfactory lobes as is often seen in mammals. In crocodiles the cerebral hemispheres have a tendency to a broad circular form. Among chelonian reptiles that region of the brain is more remarkable for height. Lizards and ophidians both have this part of the brain somewhat pear-shaped, pointed in front and elongated. The amphibian brain only differs from the lizard type in degree, and differences between lizards and amphibian brains are less noticeable than between the other orders of reptiles. The reptilian brain is easily distinguished from that of all other animals by the position and proportions of its regions. Birds have the parts of the brain formed and arranged in a way that is equally distinctive. The cerebral lobes are relatively large in convex and deserve the descriptive name hemispheres. They are always smooth as among the lower mammals and extend backward so as to a butt against the hind brain, termed the cerebellum. This junction is brought about in a peculiar way. The cerebral hemispheres in a bird do not extend backward to override the optic lobes and hide them as occurs among adult mammals, but they extend back between the optic lobes so as to force them apart and push them aside downward and backward till they extend laterally beyond the junction of the cerebrum with the cerebellum. The brain of a bird is never reptilian, but in the young mammal the brain has a very reptilian aspect, because both have their parts primarily arranged in a line. Therefore the brain appears to determine the boundary between bird and reptile exactly. Reptilian breathing organs. The breathing organs of birds and reptiles which are associated with these different types of brain are not quite the same. The frog has a cellular lung, which in the details of the minutes sacs which branch and cluster at the terminations of the tubes is not unlike the condition in a mammal. In a mammal respiration is aided by the bellows like action of the muscles connected with the ribs, which encase the cavity where the lungs are placed, and this structure is absent in the frog and its allies. The frog, on the other hand, has to swallow air in much the same way as man swallows water. The air is similarly grasped by the muscles and conveyed by them downward to the lungs. Therefore a frog keeps its mouth shut, and the animal dies from want of air if its mouth is open for a few minutes. Crocodiles commonly lie in the sun with their mouths widely open. The lungs in both crocodiles and turtles are moderately dense, traversed by great bronchial tubes, but do not differ essentially in plan from those of a frog, though the great branches of the bronchial tubes are stronger, and the air chambers into which the lung is divided are somewhat smaller. The New Zealand Hatteria has the lungs of this cellular type, though rather resembling the amphibian than the crocodile. The lungs during life in all these animals attain considerable size, the maximum dimensions being found in the terrestrial tortoises, which owe much of their elevated bulk to the dimensions of the air cells which form the lungs. The lungs of serpents and lizards are formed on a different plan. In both those groups of reptiles, the dense cellular tissue is limited to the part of the lung which is nearest to the throat. This network of blood vessels and air cells extends about the principal bronchial tube much as in other animals, but as it extends backward the blood vessels become few until the tubular lung appears in its hinder part as it extends down the body almost as simple in structure as the air bladder of a fish. Among serpents only one of these tubular lungs is commonly present, and the structure has a less efficient appearance as a breathing organ than the single lung of the fish serotitus. The chameleons are a group of lizards which differ in many ways from most of their nearest kindred, and the lungs while conforming in general plan to the lizard type in being dense at the throat and a tubular bladder in the body give off on both sides a number of short lateral branches like the fingers of a glove. Thus the breathing organs of reptiles present two or three distinct types which have caused serpents and lizards to be associated in one group by most naturalists who have studied their anatomy. While crocodiles and chelonians represent a type of lung which is quite different and in those groups has much in common. These characters of the breathing organs contribute to separate the cold-blooded armored reptiles from the warm-blooded birds clothed with feathers as well as from the warm-blooded mammals which suckle their young. For both these higher groups have denser and more elastic spongy lung tissue. It will be seen here after that many birds in the most active development of their breathing organs substantially revert to the condition of the serpent or chameleon in a somewhat modified way. Because instead of having one great bronchial tube expanded to form a vast reservoir of air which can be discharged from the lung in which the reptile has accumulated it, the bird has the lateral branches of the bronchial tubes prolonged so as to pierce the walls of the lung when its covering membrane expands to form many air cells which fill much of the cavity of the bird's body. Thus the bird appears to combine the characters of such a lung as that of a crocodile with a condition which has some analogy with the lung of a chameleon. It is this link of structure of the breathing organs between reptiles and birds that constitutes one of the chief interests of flying reptiles for they prove to have possessed air cells prolonged from the lungs which extended into the bones. Chapter 3 Of Dragons of the Air by Harry Sealy This LibriVox recording is in the public domain. A reptile is known by its bones. Such are a few illustrations of ways in which reptiles resemble other animals and differ from them in the organs by means of which the classification of animals is made. But such an idea is incomplete without noticing that the bony framework of the body associated with such vital organs also shows in its chief parts that reptiles are easily recognized by their bones. I will therefore briefly state how reptiles are defined in some regions of the skeleton for in tracing the history of reptile life the bones are the principal remains of animals preserved in the rocks and the soft organs which have perished can only be inferred to have been present from the persistence of durable characteristic parts of the skeleton which are associated with those soft organs and animals which exist at the present day and are unknown in other animals in which the skeleton is different the hang of the lower jaw the manner in which the lower jaw is connected with the skull yields one of the most easily recognized differences between the great groups of vertebrate animals in mammals in every mammal such as the dog or sheep the lower jaw which is formed of one bone on each side joins directly onto the head of the animal and moves upon a bone of the skull which is named the temporal bone this character is sufficient to prove by the law of association of soft and hard parts of the body that such an animal had warm blood and suckled its young in birds in birds a great difference is found in this region of the head the temporal bone which it will be more convenient to name the squamosal bone from its squamous or scale like form is still a part of the brain case and assists in covering the brain itself exactly as among mammals but the lower jaw is now made up of five or six bones and between the hindermost and the squamosal there is an intervening bar of bone unknown among mammalia which moves upon the skull by a joint just as the lower jaw moves upon it this movable bone unites with parts of the palate and the face and is known as the quadrate bone its presence proves that the animal possessing it laid eggs and if the face bones join its outer border just above the lower jaw it proves that the animal possessed hot blood in reptiles all reptiles are also regarded as possessing the quadrate bone but the squamosal bone with which it always unites is in less close union with the brain case and never covers the brain itself serpents show an extreme divergence in this condition from birds for the squamosal bone appears to be a loose external plate of bone which rests upon the compact brain case and gives attachment to the quadrate bone which is as free as in a bird among lizards the quadrate bone is usually almost as free in the other division of existing reptilia including crocodiles the new zealand lizard like reptile hatteria called to a terra and turtles the squamosal and quadrate bones are firmly united with the bones of the brain case face and palate so that the quadrate bone has no movement and the same condition appears in amphibians such as toads and frogs with these conditions of the quadrate bone are associated cold blood terrestrial life and young developed from eggs in fishes bony fishes and all others in which separate bones build up the skull differ from reptiles and birds much as those animals differ from mammals the union of the lower jaw with the skull becomes complicated by the presence of additional bones the quadrate bone still forms a pulley articulation upon which the lower jaw works but between it and the squamosal bone is the characteristic bone of the fish known as the hyomandibular commonly connected with opercular bones and metateragoid which intervene and help to unite the quadrate with the brain case in the cartilaginous fishes there is only one bone connecting the jaws with the skull on each side this appears to prove that just as the structure of the arch of bones suspending the jaw may be complicated by the mysterious process called segmentation which separates a bone into portions so simplification and variation may result because the primitive divisions of the material cease to be made which exists before bones are formed the principal regions of the skull and skeleton all vary in the chief groups of animals with back bones so that the reptile may be recognized among fossils even in extinct groups of animals and occasionally restored from a fragment to the aspect which characterized it while it lived end of chapter three chapter four of dragons of the air by harry sealy this libra vox recording is in the public domain animals which fly the nature of a reptile is now sufficiently intelligible for something to be said concerning flight and structures by means of which some animals lift themselves in the air it is not without interest to remember that from the earliest periods in human records representations have been made of animals which were furnished with wings yet walked upon four feet and in their typical aspect have the head shaped like that of a bird they are commonly named dragons flying dragons the effigy of the dragon survives to the present day in the figure over which saint george triumphs on the reverse of the british sovereign in the luxuriant imaginations of ancient eastern peoples dating back to prehistoric ages perhaps 5000 bc the dragons present an astonishing constancy of form in after times they underwent a curious evolution as the conception of babelon and egypt is traced through assyria to greece the wings which had been associated at first with the forelimb of the typical dragon become characteristic of the lion and of the poet's winged horse and finally of the human figure itself carved on the great columns of the greek temples of emphasis these flying animals are historically descendants of the same common stock with the dragons of china and japan which still preserve the aspect of reptiles their interest is chiefly in evidence of a latent spirit of evolution in days too remote for its meaning to be now understood which has carried the wing forms higher and ever higher in grade of organization till their wings cease to be associated with feelings of terror the hebrew cherubim are regarded by h e rile bishop of exeter as probably dragons and the figure of the conventional angel is the human form of the dragon organs of flight turning from this reference to the realm of mythology to existing nature the power of flight is popularly associated with all the chief types of vertebrate animals fishes frogs lizards birds and mammals many of the animals ill deserve the name of flyers and most are exceptions to different conditions of existence which control their kindred but it is convenient to examine for a little the nature of the structures by which this movement in the air which is not always flight is made possible certain fishes like the lung fish serratus of queensland and the mudfish lapido siren are capable of leaving the water and living on land and for a time breathe air but neither these fishes nor peri off thalamus which runs with rapid movement of its fins and carries the body more or less out of water or the climbing perch anibis carried out of water over the country by indian jugglers ever put on the slightest approach to wings flying fishes the flight of fishes is a kind of parachute support not unlike that by which a folded paper is made to travel in the air it is chiefly seen in the numerous species of a genus exocetus allied to the garpike belone which is common in tropical seas and usually from a foot to 18 inches long they merge from the water and for a time support themselves in the air by means of the greatly developed breast fins which sometimes extend backward to the tail fin although these fins appear to correspond to the forelimbs of other animals they may not be moved at the will of the fish like the wing of a bird when the flying fishes are seen in shoals in the vicinity of ships those fins remain extended so that the fish is said sometimes to travel 200 yards at a speed of 15 miles an hour rising 20 feet or more above the surface of the sea traveling in a straight line though sometimes influenced by the wind here the organ which is at once a fin and a wing consists of a number of thin long rods or rays which are connected by membrane and vary in length to form an outline not unlike the wing of a bird which tapers to a point the interest of these animals is chiefly in the fact that flight is separated from the condition of having lungs with which it is associated in birds for although the flying fish has an air bladder there is no duct to connect it with the throat flying frogs among amphibians the organs of flight are also of a parachute kind but of a different nature they are seen in certain frogs which frequent trees and are limited to membranes which extend between the diverging digits of the hand and foot forming webs as fully developed as in the foot of a swimming bird as these frogs leap the membranes are expanded and help to support the weight of the body so that the animal descends more easily as it moves from branch to branch there is no evidence that the bones of the digits ever became elongated like the fin rays of the flying fish or the wing bones of a bat but the web suggests the basis of such a wing and the possibilities under which wings may first originate by elongation of the bones of a webbed hand like that of a flying frog flying lizards the reptilia in their several orders are remarkable for absence of any modification of the arms which might suggest a capacity for acquiring wings as being latent in their organization crocodiles tortoises and serpents are alike of the earth and not of the air but among lizards there are small groups of animals in which a limited capacity for movement through the air is developed it is best known in the family of small lizards named dragons represented typically by the species draco volans found in the oriental region of the east indies and melee archipelago the organ of flight is produced in an unexpected way by means of the ribs instead of the limbs the ribs extend outward as far as the arms can stretch and the first five or six are prolonged beyond the body so as to spread a fold of skin on each side between the arm and the leg the membrane admits of some movement with the ribs this arrangement forms a parachute which enables the animal to move rapidly among branches of trees extending the structure it will so that it is used with rapidity to quick to be followed by the eye as it leaps through considerable distances a less singular aid to movement in the air is found in some of the lizards termed geckos the so-called flying gecko plattie dactylus homalocephalus has a fringe unconnected with ribs which extends laterally on the sides of the body and tail as well as at the back and front of the fore and hind limbs in between the digits where the web is sometimes almost as well developed as among tree frogs this is essentially a lateral horizontal frill extending around the body its chief interest is in the circumstance that it includes a membrane which extends between the wrist bones and the shoulder on the front of the arm that is the only part of the fringe which represents the wing membrane of a bird the fossil flying reptiles have not only that membrane but the lateral membranes at the sides of the body and behind the arms other lizards have the skin developed in the direction of the circumference of the body in the australian chlamydosaurus it forms an immense frill round the neck like a medieval collar but though such an adornment might break a fall it could not be regarded as an organ of flight flying birds the wings of birds when they are developed so as to minister to flight are all made upon one plan but as examples of the variation which the organs contributing to make the fore limb manifest I may instance the short swimming limb of the penguin the practically useless rudiment of a wing found in the ostrich or kiwi and the fully developed wing of the pigeon the wings of birds obtain an extensive surface to support the animal by muscular movements of three modifications of structure first the bones of the fore limb are so shaped that they cannot in existing birds be applied the ground for support and be used like the limbs of quadrupeds and are therefore folded up at the sides of the body and carried in an unused or useless state so long as the animal hops on the ground or walks balancing its weight on the hind legs secondly there are two small folds of skin less conspicuous than those on the arms of geckos one is between the wrist bones in the shoulder and the smaller hindermen brain is between the upper arm and the body these membranous expansions are insignificant and would in themselves be inadequate to support the body or materially assist its movements thirdly the bird develops appendages to the skin which are familiarly known as feathers and the large feathers which make the wing are attached to the skin covering the lower arm bone named the ulna and the other bones which represent the wrist and hand the area and form of the bird's wing are due to individual appendages to the skin which are unknown in any other group of animals between the extended wing of the albatross measuring 11 feet in spread and the condition in the kiwi of new zealand in which the wing is vanishing there is every possible variation in size and form as a rule the larger the animal the smaller is the wing area the problem of the origin of the bird's wing is not to be explained by study of existing animals for the rowing organ of the penguin which in itself would never suggest flight becomes an organ of flight in other birds by the growth upon it of suitable feathers anyone who has seen the birds named divers feeding underwater swimming rapidly with their wings might never suspect that they were also organs of aerial flight the ostrich is even more interesting for it has not developed flight and still retains at the extremities of two of the digits the slender claws of a limb which was originally no wing at all but the support of a four-footed animal flying mammals flight is also developed among mammals the insectivora includes several interesting examples of animals which are capable of a certain motion through the air in the tropical forests of the melee archipelago are animals known as flying squirrels flying possums flying lemurs flying foxes in which the skin extends outward laterally from the sides of the body so as to connect the four limbs with the hind limbs and is also prolonged backward from the hind limbs to the tail the four digits are never elongated the bones of the four limb are neither longer nor larger than those of the hind limb and the foot terminates in five little claws as in other four-footed animals this condition is adapted for the arboreal life which those animals live leaping from branch to branch feeding on fruits and leaves and in some cases upon insects these mammals may be compared with the flying geckos among reptiles in their parachute like support by extension of the skin which gives them one of the conditions of support which contribute to constitute flight bats one entire order of mammals the bats not only possess true wings but are capable of flight which is sustained and in some cases powerful the wings are clothed with short hair like the rest of the body and thus the instrument of flight is unlike that of a bird the flight of a bat differs from that of all other animals in being dependent upon a modification of the bones of the four limb which without interfering with the animals movements as a quadruped secures an extension of the wing which is not inferior in area to that which the bird obtains by elongation of the bones of the arm and forearm and its feathers the distinctive peculiarity of the bat's wing is in the circumstance that four of the digits of the hand have their bones prolong to a length which is often equal to the combined length of the arm and forearm the bones of the digits diverge like the ribs of an umbrella and between them is the wing membrane which extends from the sides of the body outward unites the four limb with the hind limb and is prolonged down the tail as in the flying foxes bats have a small membrane in front of the bones of the arm and forearm stretching between the shoulder and the wrist which corresponds with the wing membrane of a bird but the remainder of the membranes in bat's wings are absent in birds because their function is performed by feathers which give the wing its area the elongated digits of the bat's wing are folded together and carried at the sides of the body as though they were a few quill pins attached to its wrist where the one digit which is applied to the ground in walking terminates in a claw the organs which support animals in the air are thus seen to be more or less dissimilar in each of the great groups of animals they fall into three chief types first the parachute secondly the wing due to the feathers appended to the skin and thirdly the wing formed of membrane supported by enormous elongation of the small bones of the back of the hand and fingers the two types of true wings are limited to birds and bats and no living reptile approximates to developing such an organ of flight as a wing judged therefore by the method of comparing the anatomical structures of one animal with another which is termed comparative anatomy the existence of flying reptiles might be pronounced impossible but in the light which the revelations of geology afford our convictions become tempered with modesty and we learn that with nature nothing is impossible in development of animal structure end of chapter four chapter five of dragons of the air by harry sealy this libra vox recording is in the public domain discovery of the pterodactyl late in the 18th century in 1784 a small fossil animal with wings began to be known through the writings of colini as found in the white lithographic limestone of solenhofen in bavaria and was regarded by him as a former inhabitant of the sea the foremost naturalist of the time the citizen couvier for it was in the days of the french republic in 1801 in lucid language interpreted the animal as a genus of sariens that word so familiar at the present day was used in the first half of the century to include lizards and crocodiles and described animals akin to reptiles which were manifestly related neither to serpents nor turtles but the term sarien is no longer in favor and has faded from science and is interesting only in ancient history of progress the lizards soon became classed in close alliance with snakes and the crocodiles with the hatteria were united with colonians most modern naturalists who use the term sarien still make it an equivalent of lizard or an animal of the lizard kind couvier couvier defined this fossil from solenhofen as distinguished by the extreme elongation of the fourth digit of the hand and from that character invented for the animal the name pterodactyl he tells us that its flight was not due to prolongation of the ribs as among the living lizards named dragons or to a wing formed without the digits being distinguishable from each other as among birds nor with only one digit free from the wing as among bats but by having the wing supported mainly by a single greatly elongated digit while all the others are short and terminate in claws couvier described the amazing animal in detail part by part and such has been the influence of his clear words and fame as a great anatomist that nearly every writer in after years in french and in english repeated couvier's conclusion maintained to the end that the animal is a sarien long before fashion determined as an article of educated belief that fossil animals exist chiefly to bridge over the gaps between those which still survive the scientific men of germany were inclined to see in the pterodactyl such an intermediate type of life at first somering and vogler would have placed the pterodactyl between mammals and birds gold fuss but the accomplished naturalist gold fuss who described another fine skeleton of a pterodactyl in 1831 saw in this flying animal an indication of the course taken by nature in changing the reptilian organization to that of birds and mammals it is the first flash of light on a dark problem and its brilliance of inference has never been equalled its effects were seen when prince charles bonaparte the eminent ornithologist in italy suggested for the group the name ornithos aria when the profound anatomist de blaineville in france placed the short-tailed animal in a class between reptiles and birds named pterodactyl and andreus vogner of munich who had more pterodactyls to judge from than his predecessors saw in the fossil animal a sarian in transition to a bird von meyer but the german interpretation is not uniform and airman von meyer the banker naturalist of frankfort am mine who made himself conversant with all that his predecessors knew and enlarged knowledge of the pterodactyls on the most critical facts of structure continued to regard them as true reptiles but flying reptiles such is the influence of von meyer that all parts of the world have shown a disposition to reflect his opinions especially as they practically coincide with the earlier teaching of kouvier owen and huxley in england cope and marsh in america godry in france and zittle in germany have all placed the pterodactyls as flying reptiles their judgment is emphatic but there is weight of competent opinion to endorse the evolutionary teaching of gold fuss that they rise above reptiles to form an independent opinion the modern student must examine the animals weigh their characters bone by bone familiarize himself if possible with some of the rocks in which they are found to comprehend the conditions under which the fossils are preserved which have added not a little to the interest in pterodactyls and to the difficulty of interpretation geological history of pterodactyls in germany we may briefly recapitulate the geological history those remains of ornithosaurus which have been mentioned with the multitude of others which are the glory of the museums of munich stuttgart tubingen heidelberg bond harlem and london have all been found in working the lithographic stone of bavaria the whitish yellow limestone forms low flat topped hills now isolated from each other by natural denudation which has removed the intervening rock the stone is found at some distance north of the danube in a line due north of augsburg in the country about pappenheim and especially at the villages of solenholfen eichstitt keelheim and nusplingen these beds belong to the rocks which are named white jura limestone in germany which is of about the same geological age as the kimbridge clay in england much of it divides into very thin layers and in these planes of separation the fossils are found they include the aminides lithographicus and a multitude of marine shells king crabs and other crustacea sea urchins and other fossils showing that the deposit was formed in the sea the preservation of jellyfish which so soon disappear when left dry on the beach shows that the ancient calcareous mud had unusual power of preserving fossils into the sea with its fishes great and small came land plants from off the land dragonflies and other insects tortoises and lizards pterodactyls with their flying organs and birds still clothed with feathers sometimes the wing membranes of the flying reptiles are found fully stretched by the wing finger as in examples to be seen at munich and in the Yale museum in new haven in america at harlem there is an example in which the wing membrane appears to be folded much as in the wing of a bat when the animal hangs suspended with the flying membrane bent into a few wide undulations the solon hoof and slate belongs to about the middle period of the history of flying reptiles for they range through the secondary epics of geological time remains are recorded in germany from the kuiper beds at the top of the trius which is the bottom division of the secondary strata and i believe i have seen fragments of their bones from the somewhat older mutual cock of germany their history in england in england the remains are found for the first time in the lower liais of lime regis in dorset and the upper liais of whitby in yorkshire in vertenburg they occur on the same horizons they reappear in england in every subsequent age when the conditions of the strata and their fossils give evidence of near proximity to land in the stonesfield slate of stonesfield in oxford shire the bones are found isolated but indicate animals of some size though not so large as the rare bones of reputed true birds which appear to have left their remains in the same deposit at least two pterodactyls are found in the oxford clay known from more or less fragmentary remains or isolated bones just as they occur in the kimbridge clay purebeck limestone wielden sandstones and especially in newer secondary rocks named galt upper green sand and chalk in the southeast of england owing to exceptional facilities for collecting in consequence of the cambridge green sand being excavated for the valuable mineral phosphate of lime it contains more than a thousand bones are preserved more or less broken and battered in the woodwardian museum of the university of cambridge alone to give some idea of their abundance it may be stated that they were mostly gathered during two or three years as a matter of business by an intelligent foreman of washers of the nodules of phosphate of lime which in commerce are named copper lights he soon learned to distinguish pterodactyl bones from other fossils by their texture and learned the anatomical names of bones from specimens in the university museum this workman mr pond employed by mr william faran brought together not only the best of the remains at cambridge but most of those in the museums at york and in london and the thousands of less perfect specimens in public and private collections which passed through the present writer's hands in endeavors to secure for the university useful illustrations of the animal's structure these fragments among which there are few entire bones are valuable for they have afforded opportunities of examining the articular ends of bones in every aspect which is not possible when similar organic remains are embedded in rock in their natural connections in england flying reptiles disappear with the chalk in that period they were widely distributed being found in bohemia in brazil and kansas in the united states as well as in kent and other parts of england they attained their largest dimensions in this period of geological time one imperfect fragment of a bone from the laramy rocks of canada was described i believe by cope though not identified by him as ornithosarion and is probably newer than the other remains aspect of pterodactyls if this series of animals could all be brought together they would vary greatly in aspect and stature as well as in structure some have the head enormously long in others it is large and deep characters which are shared by extinct reptiles which do not fly and to which some birds may approximate while in a few the head is small and compact no more conspicuous relatively than the head of a sparrow the neck may be slender like that of a heron or strong like that of an eagle the back is always short and the tail may be inconspicuous or as long as the back and neck together these flying reptiles frequently have the proportions of the limbs similar to those of a bat with four legs strong and hind legs relatively small while in some the limbs are as long proportionately and graceful as those of a deer with these differences in proportions of the body are associated great differences in the relative length of the wing and spread of the wing membranes dimensions of the animals the dimensions of the animals have probably varied in all periods of geological time the smallest in the lithographic slate are smaller than sparrows while associated with them are others in which the drumstick bone of the leg is eight inches long in the Cambridge green sand and chalk imperfect specimens occur showing that the upper arm bones are larger than those of an ox the shaft is one and a half inches in diameter and the ends three inches wide such remains may indicate pterodactyls not inferior in size to the extinct Moas of New Zealand but with immensely larger heads animals far larger than birds of flight the late Sir Richard Owen on first seeing these fragmentary remains said the flying reptile with outstretched pinions must have appeared like the soaring rock of Arabian romance but with the features of leather and wings with crooked claws super induced and gaping mouth with threatening teeth eventually we shall obtain more exact ideas of their aspect when the structures of the several regions of the body have been examined the great dimensions of the stretch of wing often computed at 20 feet in the larger examples might lead to expectations of great weight of body if it were not known that an albatross with wings spreading 11 feet only weighs about 17 pounds end of chapter five chapter six of dragons of the air by Harry Sealy this LibriVox recording is in the public domain how animals are interpreted by their bones there's only one safe path which the naturalist may follow who would tell the story of the meaning and nature of an extinct type of animal life and that is to compare it as fully as possible in its several bones and as a whole with other animals especially with those which survive it is easy to fix the place in nature of living animals and determine their mutual relations to each other because all the organs vital as well as locomotive are available for comparison on such evidence they are grouped together into the large divisions of beasts birds and reptiles as well as placed in smaller divisions termed orders which are based upon less important modifications of fundamental structures all these characteristic organs have usually disappeared in the fossil hence a new method of study of the hard parts of the skeleton which alone are preserved is used in the endeavor to discover how the flying reptile or other extinct animal is to be classified and how it acquired its characters or came into existence variations of bones among mammalia resemblances and differences in the bones are easily overestimated in importance as evidence of pedigree relationship the mammalia show by means of such skeletons as are exhibited in any natural history museum how small is the importance to be attached to even the existence of any group of bones in determining its grade of organization the whole whale tribe suckle their young and conform to the distinctive characters in brain and lungs which mark them as being mammals but if there is one part of the skeleton more than another which distinguishes the mammalia it is the girdle of bones at the hips which supports the hind limbs it is characterized by the bone named the ilium being uniformly directed forward yet in the whale tribe the hip girdle and the hind limb which it usually supports are so faintly indicated as to be practically lost while the fore limb becomes a paddle without distinction of digits and is therefore devoid of hoofs or claws which are usual terminations of the extremities in mammals yet this swimming paddle with its ill-defined bones sometimes astonishing in number as well as in fewness of the finger bones is represented by the burrowing fore limb of the mole which lives underground by the elongated hoofed legs of the giraffe which lives on planes and the extended arm and finger bones of the bat which are equally mammals with the whale from such comparison it is seen that no proportion or form or length or use of the bones of the limbs or even the presence of limbs is necessarily characteristic of a mammal no limitation can be placed upon the possible diversity of form or development of bones in unknown animals when they are considered in the light of such experience of varied structural conditions in living members of a single class what is true for the limbs and the bony arches which support them is true for the backbone also for the ribs and to some extent for the skull the neck of the whale is shortened almost beyond recognition in the giraffe the same seven vertebrae are elongated into a marvelous neck so that in the technical definition of a mammal both are said to have seven neck vertebrae yet exceptions show a capacity for variation one of the sloths reduces the number to six while another has nine vertebrae in the neck proving that there is no necessary difference between a mammal and a reptile when judged by a character which is typically so distinctive of mammals as the number of the neck bones the skull varies too though to a less extent the great anteater of south america is a mammal absolutely without teeth the porpoises have a simple unvarying row of conical teeth with single roots extending along the jaw and the dental armature of the jaws and relative dimensions of the skull bones exhibit such diversity in evidence of what may be parted with or acquired that recognition of the many reptilian structures and bones in the skull of ornitho rancus the australian duckbill demonstrates that the difficulties in recognizing an animal by its bones are real unless we can discover the animal type to which the bones belong and that there is very little in osteology which may not be lost without affecting an animal's grade of organization variation in skin covering of mammals even the covering of the body varies in the same class or even order of animals so that the familiar growth on the skin is never its only possible covering the indian anteater named manis which looks like a gigantic fur cone the armadillo which sheaths the body in rings of bone bearing only a scanty development of hair are examples of mammalian hair as singular as the quills of a porcupine the horn of a rhinoceros or the growth of hair of varying length and stoutness on different parts of the body in various animals or the imperfect development of hair in the marine cetacea among living animals it is enough for practical purposes to say that a mammal is clothed with hair but in a fossil state the hair must usually be lost beyond recognition from its fineness and shortness of growth variation in skin covering of birds no class of living animals is more homogeneous than birds and well preserved remains prove that at least as far back in time as the upper olites birds were clothed with feathers of essentially the same mode of growth and appearance as the feathers of living birds there may therefore be no ground for assuming that the covering was ever different though some regions of the skin are free from feathers yet the variations from fine underdown to the scale like feathers on the wings of a penguin or the great feathers in the wings of birds of flight or the double quill of the ostrich group are calculated to yield dissimilar impressions in a fossil state even if the fine down would be preserved in any stratum variation in the bones of birds osteologically there is less variety in the skeleton of birds than in other great groups of animals the existing representatives do not exhaust its capability for modification the few specimens of birds hitherto found in the secondary strata have rudely removed many differences in the bones which separated living birds from reptiles so that if only the older fossil birds were known and the tertiary and living birds had not existed a bird might have been defined as an animal having its jaw armed with teeth instead of devoid of teeth with vertebrae cupped at both ends instead of with a saddle shaped articulation which in front is concave from side to side and convex from above downwards in which the bones of the hand are separate so that three digits terminating in claws can be applied to the ground instead of the metacarpal bones being united in a solid mass with clawless digits and in which the tail is elongated like the tail of a lizard yet the limits to variation are not to be formulated till nature has exhausted all her resources in efforts to preserve organic types by adapting them to changed circumstances birds may be regarded theoretically as equally capable with mammals of parting with almost every distinctive structure in the skeleton by which it is best known even the living frigate bird blends the early joints of the backbone into a compact mass like a sacrum the penguin has a cup and ball articulation in the early dorsal vertebrae with the ball in front and the genus sypsilis has the upper arm bone almost as broad as long unlike the bird type such examples prove that we are apt to accept the predominant structures in an animal type as though they were universal and forget that inferences based like those of early investigators on limited materials may be reexamined with advantage variation in the bones of reptiles the true reptilia nonwithstanding some strong resemblances to birds in technical characters of the skeleton display among their surviving representatives an astonishing diversity in the bony framework of the body exceeding that of the mammalia this unlooked for capacity for varying the plan of construction of the skeleton is in harmony with the diversity of structure in groups of extinct animals to which the name reptiles has also been given the interval in form is so vast between serpent and tortoise and so considerable in structure of the skeleton between these and the several groups of lizards crocodiles and hatteria that any other diversity could not be more surprising and the inference is reasonable that just as mammals live in the air in the sea on the earth and burrow under the earth similar modes of existence might be expected for birds and reptiles though no bird is yet known to have put on the aspect of a fish and no reptiles have been discovered which roamed in herds like antelopes or lived in the air like birds or bats unless these fossil flying animals prove on examination to justify the name by which they are known comparative study of structure in this way demolishes the prejudice born of experience of the life which now remains on earth that the ideas of reptile and of flight are incongruous and not to be combined in one animal the comparative study of the parts of animals does not leave the student in a chaos of possibilities but teaches us that organic structures which mark the grades of life have only a limited scope of change while nature flings away every part of the skeleton which is not vital or changes its form with altering circumstances of existence enforced by revolutions of the earth's surface in geological time in her efforts to save organisms from extinction and pass the grade of life onward to a later age the bones are only of value to the naturalist as symbols inherited or acquired and very in value as evidence of the nature and association of those vital organs which differentiate the great groups of the vertebrata these distinctive structures which separate mammals birds and reptiles are sometimes demonstrated by the impress of their existence left on the bones or sometimes they may be inferred from the characters of the skeleton as a whole end of chapter six chapter seven of dragons of the air by harry sealy this libra vox recording is in the public domain interpretation of pterodactyls by their soft parts the organs which fix an animal's place in nature we shall endeavor to ascertain what marks of its grade of organization the pterodactyl has to show the organs which are capable of modifying the bones are probably limited to the kidneys the brain and the organs of respiration it may be sufficient to examine the latter two pneumatic foramina in pterodactyls hermon von meyer the historian of the ornithosaurs of the lithographic slate as early as 1837 described some pterodactyl bones from the liais of franconia which showed that air was admitted into the interior of the bones by apertures near their extremities which from this circumstance are known as pneumatic foramina he drew the inference naturally enough that such a structure is absolute proof that the pterodactyl was a flying animal it was not quite the right form in which the conclusion should have been stated because the ostrich and other birds which do not fly have the principal bones pneumatic afterwards in 1859 the larger bones which professor sedgwick of Cambridge transmitted to sir Richard Owen established this condition as characteristic of the flying reptiles of the Cambridge green sand it was thus found as a distinctive structure of the bones both at the beginning and the close of the geological history of these animals von meyer remarks that the supposition readily follows that in the respiratory process there was some similarity between pterodactyls and birds this cautious statement may perhaps be due to the circumstance that in many animals air cavities are developed in the skull without being connected with organs of respiration it is well known that the bulk of the elephant's head is due to the brain cavity being protected with an envelope formed of large air cells small air cells are seen in the skulls of oxen pigs and many other mammals as well as in the human forehead the head of a bird like the owl owes something of its imposing appearance to the way in which its mass is enlarged by the dense covering of air cells in the bones above the brain like that seen in some cretaceous pterodactyls nor are the skulls of crocodiles or tortoises exceptions to the general rule that an animal's head bones may be pneumatic without implying a pneumatic prolongation of air from the lungs the mere presence of air cells without specification of the region of the skeleton in which they occur is not remarkable the holes by which air enters the bones are usually much larger in pterodactyls than in birds but the entrance to the air cell prolonged into the bones is the same informant position in both groups so far as can be judged by this character there is no difference between them the importance of the comparison can only be appreciated by examining the bones side by side in the upper arm bone of a bird on what is known as the ulnar border near to the shoulder joint and on the side nearest to it is the entrance to the air cell in the humerus in the pterodactyl the corresponding foramen has the same position form and size and is not one large hole but a reticulation of small perforations one beyond another exactly such as are seen in the entrance to the air cell in the bone of a bird in which the pneumatic character is found for it is not every bird of flight which has this pneumatic condition of the bones and dr. crisp stated that quite a number of birds the swallow martin snipe canary wood ren and willow ren wind chat glossy starling spotted fly catcher and black-headed bunting have no air in their bones and it is well known that in many birds especially water birds it is only the upper bones of the limbs which are pneumatic while the smaller bones retain the marrow it may be well to remember that the lungs of a bird are differently conditioned from those of any other animal instead of hanging freely suspended in the cone shaped chamber of the thorax formed by the ribs and sternum they are firmly fixed on each side so that the ribs deeply indent them and hold them in place the lungs have the usual internal structure being made up of branching cells the chief peculiarity consists in the way in which the air passes not only into them but through them the air tube of the throat of a bird unlike that of a man has the organ of voice not at the upper end in the form of a larynx but at the lower end forming what is termed a syrinx there is no evidence of this in a fossil state although in a few birds the rings of the trachea become ossified and are preserved but below the syrinx the trachea divides into two bronchi tubes which carry the ringed character into the lungs for some distance and these give off branches termed bronchial tubes the finer subdivisions from which in their clustered minute branching sacks make up the substance of the lung there is nothing exceptional in that but towards the outer or middle part of the ventral or under surface of the lungs four or five rounded openings are seen on each side each of these openings resembles the entrance of the air cell into a bone since it displays several smaller openings which lead to it each opening from the lung leads to an air cell these cells may be regarded as the blowing out of the membrane which covers the lungs into a film which holds air like a mass of soap bubbles until the whole cavity of the body of a bird from neck to tail is occupied by saculated air cells commonly ten in number five on each side though two frequently blend at the base of the neck in the region of the V shaped bone named the clavicle or furculum popularly known as the merry thought most people have seen some at least of these semi-transparent bladder like air cells beneath the skin in the abdominal region of a foul the cells have names from their positions and on each side one is abdominal two are thoracic one clavicular and one cervical which last is at the base of the neck the clavicular and abdominal air cells are perhaps the most interesting the air cell termed clavicular sends a process outward towards the arm along with the blood vessels which supply the arm thus this air cell entering the region of the axilla or armpit enters the upper arm bone usually on its underside close to the articular head of the humerus and in the same way the air may pass from bone to bone through every bone in the forelimb the hind limbs similarly receive air from the abdominal air cell which supplies the femur and other bones of the leg the sacrum and the tail but the joints of the backbone in front of the sacrum receive their air from the cervical air sac the air cells are not limited to the bones but ramify through the body and in some cases extend among the muscles a bird may be said to breathe not only with its lungs but with its whole body and it is even affirmed that respiration has been carried on through a broken arm bone when the throat was closed and the bird underwater birds differ greatly in the extent to which the air cell system prolonged from the lungs is developed some having the air absent from every bone while others like the swift are reputed to have air in every bone of the body comparison shows that in so far as the bones are the same in bird and ornithosaur the evidence of the air cells entering them extends to resemblance if not coincidence in every detail no living group of animals except birds has pneumatic limb bones in relation to the lungs so that it is reasonable to conclude that the identical structures in the bones were due to the same cause in both the living and extinct groups of animals it is impossible to say that the lungs were identical in birds and pterodactyls but so far as evidence goes there is no ground for supposing them to have been different the lungs of reptiles there is nothing comparable to birds either in the lungs of living reptiles or in their relation to the bones the chameleon is remarkable in that the lung is not a simple bladder prolonged through the whole length of the body cavity as in a serpent but it develops a number of large lateral branches visible when the body is laid open except near the trachea where the tissue has the usual density of a lizard lung the air cell is scarcely more complicated than the air bladder of a fish and does not enter into any bone of the skeleton and although many fishes like the loach have the swim bladder surrounded by bone connected with the head it offers no analogy to the pneumatic condition of the bones in the pterodactyl the form of the brain cavity but the identity of the pneumatic foramina in birds and flying reptiles is not a character which stands by itself as evidence of organization for a mold of the form of the brain case contributes evidence of another structural condition which throws some light on the nature of ornithosaurs among many of the lower animals such as turtles the brain does not fill the chamber in the dry skull in which the same bones are found as are molded upon the brain in higher animals for the brain case in such reptiles is commonly an envelope of cartilage as among certain fishes and except among serpents the ophidia the bones do not completely close the reptilian brain case in front the brain fills the brain case completely among birds a mold from its interior is almost as definite in displaying the several parts of which it is formed as the actual brain would be and the chief regions of the brain in a bird cerebrum optic lobes cerebellum show singularly little variation in proportion or position the essential fact in a bird's brain which separates it absolutely from all other animals is that the pair of nerve masses known as the optic lobes are thrust out at the sides so that the large cerebral hemispheres extend partly over them as they extend between them to a butt against the cerebellum this remarkable condition has no parallel among other vertebrate animals in fishes amphibians reptiles and mammals the linear succession of the several parts of the brain is never departed from and any appearance of variation from it among mammals is more apparent than real for the linear succession may be seen in the young calf till the cerebral hemispheres grow upward and lop backward so as to hide the relatively small brain masses which correspond to the optic lobes of reptiles extending over these corpora quadra gemina as they are named so as to cover more or less of the mass of the cerebellum from these conditions of the brain and skull it would not be possible to mistake a mold from the brain case of a bird for that of a reptile though in some conditions of preservation it is conceivable that the mold of the brain of a bird might be distinguished with difficulty from that of the brain in the lowest mammals taken by itself the avian form of brain in an animal would be as good evidence that its grade of organization was that of a bird as could be offered the brain in sullen hofen pterodactyls it happens that molds of the brain of pterodactyls more or less complete are met with of all geological ages liacic olytic and cretaceous the sullen hofen slate is the only deposit in europe in which pterodactyl skulls can be said to be fairly numerous they commonly have the bones so thin as to show the form of the upper surface of the mold of the brain or the bones have scaled off the mold or remain in the counterpart slab of stone so as to lay bare the shape of the brain mass in the museum at heidelberg a skull of this kind is seen in the long-tailed genus of pterodactyls named rampharencus it shows the large rounded cerebral hemispheres which extend in front of cerebral masses of smaller size a little below them in position which perhaps are as like the brain of a monotreme mammal as a bird the short-tailed pterodactyl is described by coupier has the cerebral hemispheres very similar to those of a bird but the relations of the hinder parts of the brain to each other are less clear the first specimen to show the back of the brain was found by mr john francis walker m a in the cambridge greensand i was able to remove the thick covering of cellular bone which originally extended above it and thus expose evidence that in the mutual relations of the four and hind parts of the brain bird and ornithosaur were practically identical another cambridge greensand skull showed that in the genus ornithochiris the optic lobes of the brain are developed laterally as in birds that skull was isolated and imperfect but about the same time the late reverend w fox of brickston in the isle of white obtained from willed in beds another skull with jaws teeth and the principal bones of the skeleton which showed that the willed in pterodactyl ornitho desmos had a similar and bird-like brain in 1888 mr et newton frs obtained a skull from the upper lias uncrushed and free from distortion this made known the natural mold of the brain which shows the cerebral hemispheres optic lobes and cerebellum more distinctly than in the specimens previously known in some respects it recalls the heidelberg brain of ramp for rancous in the apparently transverse subdivision of the optic lobes but it is unmistakably bird-like and quite unlike any reptile importance of the brain and breathing organs so far as the evidence goes it appears that these fossil flying animals show no substantial differences from birds either in the mold of the brain or the impress of the breathing organs upon the bones these approximations to birds of the nervous and respiratory systems which are beyond question two of the most important of the vital organs of an animal and distinctive beyond all others of birds place the naturalist in a singular dilemma he must elect whether he will trust his interpretation to the soft organs which among existing animals never vary their type in the great classes of vertebrate animals and on which the animal is defined as something distinct from its envelope the skeleton and its appendages the limbs or whether he will ignore them the answer must choose substantially between belief that the existing order of nature gives warrant for believing that these vital characteristics which have been discussed might equally coexist with the skeleton of a mammal or a reptile as with that of a bird for which there is no particle of evidence in existing life or as an alternative the fact must be accepted that birds only have such vital organs as are here found and therefore the skeleton that may be associated with them cannot affect the reference of the type to the same division of the animal kingdom as birds the decision need not be made without further consideration but brain and breathing organs of the avian type are structures of a different order of stability in most animals from the bones which vary to a remarkable extent in almost every ordinal group of animals temperature of the blood the organs of circulation and digestion are necessarily unknown there are reasons why the blood may have been hot such as the evidences from the wings of exceptional activity though the temperature depends more upon the amount of blood in the body than upon the apparatus by which it is distributed we speak of a crocodile as cold blooded yet it is an animal with a four chambered heart not incomparable with that of a bird on the other hand the Tony a sort of giant mackerel is a fish with a three chambered heart only breathing the air dissolved in water which has blood as warm as a mammal its temperature being compared to that of a pig several fishes have blood as warm as that of manus the scaly anteater and many birds have hotter blood than mammals the term hot blooded as distinct from cold blooded applied to animals is relative to the arbitrary human standard of experience and expresses no more than the circumstance that mammals and birds are warmer animals than reptiles and fishes the exceptional temperature of the flying fish has led to a vague impression that physical activity and its effect upon the amount of blood which vigor of movement circulates are more important in raising an animal's temperature than possession of the circulatory organs commonly associated with hot blood which drive the blood in distinct courses through the body and breathing organs yet the kind of heart which is always associated with vital structures such as pterodactyls are inferred to have possessed from the brain mold and the pneumatic foramina in the bones is the four chambered heart of the bird and the mammal considering these organs alone of which the fossil bones yield evidence we might anticipate by the law of known association of structures that nothing distinctly reptilian existed in the other soft parts of the vital organization because there's no evidence in favor of or against such a possibility end of chapter seven