I ^y 0» 'y ^ S' FOR THE PEOPLE FOR EDVCATION FOR SCIENCE LIBRARY OF THE AMERICAN MUSEUM OF NATURAL HISTORY "^ <^ THE STORY OF THE BIRDS From Arch^opteryx to Bird of Paradise. THE STORY OF THE BIRDS BEING AN INTRODUCTION TO THE STUDY OF ORNITHOLOGY ^^/^^/^^ ft BY CHARLES DIXON AUTHOR OF "rural bird life," "the game birds and wild fowl of the BRITISH ISLANDS," "BRITISH SEA BIRDS," "CURIOSITIES OF BIRD LIFE," " THR MIGRATION OF BIRDS," " BIRD LIFE IN A SOUTHERN COUNTY," "among THE BIRDS IN NORTHERN SHIRES," ETC. ETC. ETC. WITH FRONTISPIECE BY CHARLES WHY M PER LONDON GEORGE ALLEN, 156, CHARING CROSS ROAD 1900 All rights reserved "ROSE HILL" W^'^^'TIVOLI P.O. DUCHESS CO.. N- Y Printed by Ballantyne, Hanson &' Co. At the Ballantyne Press PREFACE There are many people who take an intelligent interest in Birds and their Habits, and would like to acquire a more extended knowledge of ornithology were they not discouraged by the dry and technical manner in which such infor- mation is usually conveyed. The present volume has been written with a view to removing some at least o^ these obstacles to the acquisition of a general knowledge of Birds. We have sought to tell their story simply and in language as free from technicalities as possible ; to produce a guide or handbook to the study of birds that shall be both popular and accurate as we can make it. We make no pretensions to complete- ness or finality, for such could scarcely have been even approximately reached had each chapter been expanded into a volume ; but we do claim for our work that no reader can master its contents without gaining a very general know- ledge of the avine kingdom. Whilst always vi PREFACE endeavouring to make the Story popular we trust we have never done so at the expense of its philosophic importance. The Story that the Birds have to tell us is indeed a fascinating one. Beginning with the Origin and Descent of Birds during geological epochs so remote that the mind fails to grasp or realise the mighty vastness of time that separ- ates the Then from the Now, we pass on to a consideration of their salient characteristics in existing forms, their anatomical features, the bony framework and internal organs, the pecu- liarities of their dermal covering, its structure, colours, and functions. Then we take up the subject of the various Groups or Orders into which systematists have divided Birds, the com- position of those orders, the affinities and pecu- liarities of the species in them. After which we trace out the Distribution of Birds over the earth, and then endeavour to ascertain the conditions of their Dispersal and the laws that govern their Migrations. Then comes the subject of the General Habits and Functions of Birds — their Flight, terrestrial and aquatic motions, Social Instincts, Food, and the many methods of obtain- ing it, the Mimicry of Birds, their Protective Colouration and Resemblances, Variation and PREFACE vii Dimorphism. Our next stage in their Story brings us to their marvellous methods of Court- ship, their Love Displays, their bridal Songs and Cries and Sounds. This is fittingly succeeded by a scientific study of their Nests and Eggs, which brings their Story to a close. CHARLES DIXON. Paignton, S. Devon. CONTENTS CHAPTER I THEIR ORIGIN AND SALIENT CHARACTERISTICS PAGES Diagnosis of a bird — Descent of birds — ArchcCopteryx — Cretaceous Ornitholites — Upper Eocene Orni- tholites — Miocene Ornitholites — Pliocene Orni- tholites— Tertiary gigantic birds — New Zealand Moas — Mdttagascar ^pyornithes — Miocene tropi- cal genera in Europe — The feathers of birds — Contour feathers — D own-plumes — Powder-downs — Filoplumes — Colour of feathers — Abnormal colouration — Arrangement and pattern of colour — Differences in colour due to age, sex, and season — Colour and environment — Moulting — The avine skeleton — The anterior and posterior limbs — The head or skull — Internal organs — Muscular, ner- vous, and digestive systems — Respiratory organs — The young of birds 1-53 CHAPTER n THE PRINCIPAL BIRD GROUPS The two Primary Divisions — The Carinata: and Ratita2 — Moas and Rocs — Rheas, Cassowaries, and Emus — Kiwis and Ostriches — The Crypturi or Tinamous — The Impennes or Penguins — The Colymbiformes or Divers and Grebes — The ix CONTENTS PAGES Procellariiformes or Petrels — The Pelargiformes or Herons, Storks, Spoonbills, and Ibises — The Pelecaniformes or Tropic Birds, Gannets, Cor- morants, Pelicans, Darters, and Frigate Birds — The Anseriformes or Swans, Geese, Ducks, and Mergansers — The Gruiformes or Cranes and allied birds — The Ralliformes or Rails and Finfoots — The Galliformes or Game Birds — The Pediophili or Sand-Grouse — The Columbiformes or Pigeons — The Charadriiformes or Bustards, Plovers, Sandpipers, Jacanas, Sheath-bills, Crab Plover, and Seed Snipes — The Lariformes or Gulls, Terns, Skuas, and Skimmers — The Alci- formes or Auks — The Falconiformes or Birds of Prey — The Coraciiformes — The Psittaciformes or Parrots — The Cuculiformes or Cuckoos and Plantain-Eaters — The Passeriformes or Perching Birds 54-102 CHAPTER HI THEIR DISTRIBUTION IN SPACE The geographical distribution of birds — Views of Sclater, Huxley, and Wallace — Dr. Sclater's Zoo- logical Regions — The Pala^arctic Region : its characteristic birds — The Ethiopian Region : its characteristic birds — The Indian or Oriental Region : its characteristic birds — The Australian Region : its characteristic birds — The Nearctic Region : its characteristic birds — The Neotropical Region : its characteristic birds — Distribution of the Moas and Rocs — Distribution of Ratitae birds — Distribution of Carinatir: birds — The Tinamous — The Penguins — The Divers and Grebes — The Petrels — The Herons, Storks, Spoonbills, and Ibises — The Tropic Birds, Gannets, Cormorants, CONTENTS xi Pelicans, Darters, and Frigate Birds — The Screamers, Flamingoes, Swans, Geese, Ducks, and Mergansers— The Finfoots and Rails— The Cranes, Trumpeters, Screamers, and Sun Bitterns — The Game Birds— The Sand-Grouse — The Pigeons —The Plovers and Snipes, &c.— The Gulls, Terns, Skuas— The Auks — The Birds of Prey — The Coraciiformes— The Parrots— The Cuckoos and Plantain-Eaters — The Passeriformes or Perching Birds PAGES 103-142 CHAPTER IV THEIR MEANS OF DISPERSAL AND MIGRATIONS The dispersal of birds— Fortuitous dispersal— Ancient land-surfaces— Polar dispersal— Equatorial disper- sal—The law of dispersal— Obstacles to dispersal — Discontinuous areas of dispersal— Influence of climate upon species — Species increasing their range during present time— The migration of birds — Misconceptions concerning migration — Transmutation and Hibernation — Migration and Instinct — Migration not universal in certain species — The Cause of Migration — Migration due to range expansion or colonisation — Cause of migration in autumn— Length of journey variable— The Philo- sophy of Migration — The wings of migrants — Moulting of migrants— Course of autumn migra- tion— How birds find their way on migration — Migration across seas— General aspects of migra- tion— Duration of migration — The speed of migra- tion flight— The height at which migrating birds fly — The perils of migration — Lost birds at lighthouses — Various kinds of migration — Vertical migration— Local movements of birds— Nomadic migration — Irruptic movements . . . 143-177 xii CONTENTS CHAPTER V THE GENERAL HABITS AND FUNCTIONS OF BIRDS PAGES The flight of birds — Flightless birds— The fitness of birds for an aerial existence — Various modes of flight — Gliding flight : how performed — Flight by active strokes of the wings : how performed — The movement of the wings — Soaring or sailing flight : how performed — Terrestrial and aquatic motion of birds — Birds unable to progress upon the land — Running, walking, and hopping move- ments— Progress in water — The food of birds — Modifications of the bill — Common to various distantly related groups — Social, gregarious, or solitary instincts of birds — Mimicry in birds — Protective colours and resemblances of birds — Forest birds — Desert birds — Marsh and swamp birds — Moorland and mountain birds — Arctic birds — Variation in birds — Of external structure and colour — Dimorphism in birds — Sexual dimor- phism— Dimorphism independent of sex — Struc- tural dimorphism 1 78-211 CHAPTER VI THE LOVE DISPLAYS OF BIRDS Bird music — Vocal music of birds — Variety in song — Capriciousness of song — The origin and purpose of avine song — Individual variation in the song of birds — Imitation — Do birds sing by instinct or imitation? — Vocal sounds of birds — The in- strumental music of birds — Made by ordinary appliances — Made by special modifications of the plumage — The drumming of the Snipe — Modifications in the wings of the PIumming-Birds CONTENTS xiii PAGES — In other species — Wing modification in the Manakins — Sounds made by air sacs or pouches — The love displays of birds — Aerial displays of Humming-Birds — Of Tyrant Birds — Love displays of the Birds of Paradise — Of Bustards — The love- posturing of the Argus Pheasant — The Bower Birds — Their curious " bowers " — The dances of certain Rails — Of the South American Jacana — Of the Spur-winged Plover — Of certain Ducks — Parades of plumage — The meaning and purpose of this display — Sexual selection — The vitality, excitability, and pugnacity of birds . . 212-242 CHAPTER VII THEIR REPRODUCTION (nESTS) The unique character of birds' nests — The architecture of Ratitas Birds — The nests of the Kingfishers — The Hornbills — The Swifts — Edible nests — The nests of the Humming-Birds — Nests of the Passeriformes — Great variety in the nests of the Passeres — Variation of nest-type in the same species — Uniformity in the nests of species — The architecture of the Wrens — Of the Swallows — Of the Finches — Of the Starlings, Shrikes, Wax- wings, Orioles, and Goldcrests — Nests of the Tropical Oscines — In the Timeliidae — The Tailor Bird — Nests of the Bulbuls, Cuckoo Shrikes, Drongos and Greenlets — Of the Birds of Paradise — Of the Sun-Birds — Of the Flower-peckers and Sugar Birds — Of the Wood Warblers and Tanagers — Of the Weaver Birds — Of the Ox Birds and Hang-nests — Of the Broadbills — Of the Pittas— Of the Tyrant Birds— Of the Cotingas and Plant-cutters — The nest of the Oven Birds — . The architecture in the Wood Hewer family — Of xiv CONTENTS PAGE the Ant Thrushes — Of the Lyre Birds — Nest of the Hammer-Head — Nests of the Mound Birds — Of the Brush Turkeys — Of certain Coursers — Of the Rails, Ducks, and Geese — Of the Flamingoes — The utility of nests — The nest in relation to the colour of the plumage — Instinct or imitation in nest-building . . . . . . 245-276 CHAPTER VIII THEIR REPRODUCTION (eGGS) Eggs — The development of the shell — The deposition of the colour pigments — The shape of the mark- ings— How formed — The two types of markings — Their distribution — General resemblances amongst eggs of the same species — Exceptions — Composi- tion of the colour pigments — The incubation of the egg — Incubation periods in the various avine orders — The incubating sex — The texture or grain of the egg-shell — The colour of the interior of the shell — The form of eggs — The size of eggs — The number of eggs produced by species in the various groups — The colours of eggs — Generic types of eggs — Variation in the colour of eggs in the same species — Of the Guillemot — Of the Cuckoo — Uniformity of colour in other groups — The colours of eggs hereditary — Eggs of hybrids — The ances- tral colour of eggs — The utility of colour — White eggs in covered nests — In open nests — Spotted eggs in open nests — In covered nests — The pro- tective colouration of newly hatched birds . 277-304 THE STORY OF THE BIRDS CHAPTER I THEIR ORIGIN AND SALIENT CHARACTERISTICS Diagnosis of a bird — Descent of birds — Archseopteryx — Cretaceous Ornitholites — Upper Eocene Ornitholites — Miocene Ornitholites — Pliocene Ornitholites — Tertiary gigantic birds — New Zealand Moas — Madagascar -^py- ornithes — Miocene tropical genera in Europe — The feathers of birds — Contour feathers — Down-plumes — Powder-downs — Filoplumes — Colour of feathers — Ab- normal colouration — Arrangement and pattern of colour ■ — Differences in colour due to age, sex, and season — Colour and environment — Moulting — The avine skeleton — The anterior and posterior limbs — The head or skull — Internal organs — Muscular, ner- vous, and digestive systems — Respiratory organs — The young of birds. " What is a man ? " asks Galatea of Pygmalion in Mr. Gilbert's famous play. *' What is a bird ? " the curious reader may ask, and possibly ask ninety-nine people out of every hundred without obtaining any satisfactory definition of such a well-known and familiar creature. Birds are familiar to all of us. To almost every kind A 2 THE STORY OF THE BIRDS of scene they impart an ever-welcome sense of life ; whilst of all organisms they are as a class the most beautiful, the most tuneful, and we may even add the most widely and generally interesting. The old proverb that '^A bird is known by its feathers " amounts to a strictly scientific diagnosis of the class Aves, for feathers are otherwise unknown in the animal kingdom, and therefore become the most important char- acteristic of a bird. There can be no reason- able doubt that birds are more closely related to reptiles than to any other class of animal life. The close propinquity of the two classes — reptiles and birds — was unreservedly recognised by Huxley, that great comparative anatomist associating both under the term Sauropsida, the two combined forming one of the three primary groups into which he divided vertebrated animals. It might reasonably be thought that as birds are so obviously closely related to reptiles, the descendants in fact of one common ancestor from which both classes of organisms (Reptilia and Aves) have sprung, there would be definite evidence in existence, in a fossil form, to indi- cate the line of their descent. But although we may be practically certain that birds and ORIGIN AND CHARACTERISTICS 3 reptiles are more closely related to each other than either is to all remaining forms of vertebrate life, nothing displaying nearer afBnities with birds than those gigantic reptilian forms known as Dinosaurs have yet been discovered. Casts of footprints found upon the Triassic sandstone in the valley of the Connecticut in New England were long supposed to be those of birds, but palaeontologists appear now to be generally agreed that these impressions were made by the feet of Dinosaurian reptiles. Some of these footprints, measuring as many as seventeen inches in length, indicate creatures of vast size with a stride of about eight feet ! Dr. Hitchcock enumerates the footprints of as many as twenty- three species of what he termed Ornithichnites — a Greek compound, signifying fossil footprints of birds, and which of course in the light of modern opinion now becomes obsolete. From the Bunter Sandstein of the Triassic system to the Solenhofen slate formation of the Jurassic system constitutes a vast period of geological time, and yet this separates these reputed Orni- thichnites from the first really fossil bird respect- ing the identity of which authorities are in no doubt. This, the earliest known avine form, is the Archaeopteryx (a second species has lately 4 THE STORY OF THE BIRDS been described from the same locality), a crea- ture which, although presenting not a few reptilian characteristics, was unquestionably dur- ing life a feather-clad bird. The Archaeopteryx was a bird about the size of a Crow, with a short blunt bill. The upper jaw was furnished with thirteen and the lower jaw with three conical teeth on each side, each embedded in a distinct socket. This curious bird was also furnished with a long lizard-like tail composed of twenty- one vertebrae, from each of the first twelve of which grew a pair of feathers. The three free digits of the wing were armed with claws. Of course nothing can be said with certainty re- specting the habits and mode of life of the Archasopteryx, but the structure of the feet suggest a possible arboreal existence. The next known bird forms (Ornitholites) appear in the Cretaceous epoch. All these, so far as is known, still continue to present the character of teeth, but the lizard-like tail com- pletely disappears. Many of the remains found in the deposits of this epoch, and formerly beheved to be Ornitholites, have been shown to be those of Pterodactyls (bat-like reptiles). However, in 1858, undoubted avine remains (of a form believed by some authorities to be allied ORIGIN AND CHARACTERISTICS 5 to the modern Divers) were discovered by Barrett in the Upper Greensand of Cambridge- shire ; others obtained from the chalk forma- tion of South Sweden have been described by Professor Dames. A much more extensive series of OrnithoHtes (referable to no less than seven genera) from the Cretaceous rocks of North America have been, described by Professor Marsh. Two of these, from the shales of Kansas, formed his distinct sub-class Odontornithes, but as all Cretaceous birds are believed to have been toothed the term has more recently been employed to embrace all OrnithoHtes of that epoch. The list of Pre-Tertiary OrnithoHtes is comparatively a small one. As might naturally be inferred OrnithoHtes become much more numerous in Tertiary deposits. Avine evolution must have been progressing upon a vast scale during the closing ages of the Cretaceous and the early eras of the Tertiary systems ; and not only do we find a much greater and most significant wealth of avine fossils, but a steady progress towards those types which dwell upon the earth in our own time, or which occupied it in ages not very remotely preceding the present. Some of the most remarkable Orni- thoHtes of the early Tertiary Period relate to 6 THE STORY OF THE BIRDS such gigantic avine forms as Gastornis. Fossil remains of this bird have been discovered in the south of England (near Croydon), as well as on the Continent. Specialists are by no means agreed respecting its affinities, but its large size is indisputable, bigger than an Ostrich, and like that bird incapable of flight. Another remarkable Ornitholite belonging to this era of strange avine forms is the Odontopteryx toliapica from the London Clay of Sheppey, represent- ing the remains of a bird possessing curiously serrated jaws. At this era appear the remains of Halcyornis (also from the Sheppey beds), considered by some to be allied to the Gulls ; of Proherodius, showing affinities with the Herons ; and Lithornis, provisionally associated by Owen with the Birds of Prey, but possibly more nearly allied to the Cranes. Osteornis from the shale of Plattenberg at Glarus may belong to the present wide-ranging and domi- nant order of the Passeres. Passing on to the Ornitholites of the Upper Eocene we have the remarkable series of avine remains from the Paris Basin, with the identi- fication and comparison of which the names of Cuvier and Milne-Edwards are so inseparably associated. Of the fourteen genera to which ORIGIN AND CHARACTERISTICS 7 Milne-Edwards referred the various remains no less than half are still existent, whilst the other seven are more or less closely allied to others in a similar state. Precisely the same remarks apply to the Ornitholites of this period from equivalent beds in other parts of Europe, in- cluding our own islands, but the remains of many additional species have been discovered, most of them more or* less distantly allied with types that are living in our own era, although in not a few cases not in the same geographical areas as was then the case. The Ornitholites of North America tell a very similar story ; whilst a most interesting avine fossil of this period from New Zealand, Palaeeudyptes antarc- ticus, a giant Penguin standing seven feet high, is specially worthy of mention. The Ornitholites peculiar to the Miocene Period, as might naturally be expected, still continue to present, and in increasing abund- ance, characters which indicate still closer affinities with genera and species of birds that are in existence now. Some of course of those fossils represent types that have completely disappeared from the earth, but in few cases do we find such vast distinctions that characterise the Ornitholites of earlier eras, an eloquent and 8 THE STORY OF THE BIRDS most significant demonstration of the wonder- ful progress of avine evolution. Two of the most remarkable types of this era are Phoro- rhacos and Brontornis. These avine giants are from the Miocene deposits of South America. These, together with several other genera (in all we believe eight or nine are recognised), com- prise what shortly after their discovery was supposed to be an absolutely new order of birds to which the name Stereornithes was applied, but which subsequently was declared to possess no such taxonomic importance. These very wonderful bird remains, the existence of which was only discovered a decade ago, appear to indicate a rich avifauna in South America even at that remote era, and form evidence of a most significant kind relating to the dispersal of life over the globe. The most remarkable feature of these birds is the enormous size and massive structure of the head, in comparison with the limbs, although some of these are of gigantic proportions. Probably we never shall have any but the faintest idea of what these bird monsters were actually like in fife, but that they must have presented a most impressive appearance with their huge laterally compressed and hooked beak, cannot be doubted. That ORIGIN AND CHARACTERISTICS 9 they were unable to fly seems certain. Some Ornitholites of this era found in Europe are intermediate between the Storks and Ibises (Ibidopodia), another a species allied to the Flamingoes (Palaelodus). We must attribute the comparative scarcity of Ornitholites in the Pliocene deposits either to the prevailing con- ditions at that time being unsuitable for their effectual preservation or to our own want of success in discovering them. The fragments of the Pliocene avifauna so far as they have been revealed by scientific investigation represent the remains of birds differing little from types existing to-day, w^hilst many of them were undoubtedly generically and in some cases possibly specifically the same. A significantly still greater similarity characterises the avine remains of the Post-Tertiary Period ; whilst the geographical area occupied by these Pleistocene birds is in most cases the same as that of their surviving representatives or de- scendants. In the majority of instances these Post-Tertiary relics are, so far as we can judge, of the same species that exist to-day. Some of course have become extinct altogether, as for instance the Crane (Grus primigenia) and the Pelican, remains of which latter have been lo THE STORY OF THE BIRDS discovered in the English Fens ; others have disappeared from scenes which their remains tell us they once occupied ; as for instance the Snowy Owl and the Capercailzie from Devon- shire, bones of which have been found in that wonderful necropolis of our ancient fauna, Kent's cavern, near Torquay. Two other points seem specially worthy of a brief notice before we leave this portion of the subject. The first relates to the gigantic birds of the early Tertiary Period. There can be no doubt that some at least of these ponderous avine types managed to survive in one or two favourable spots until quite recent times and long after their contemporaries had vanished from the earth. The two most famous sanctu- aries of these archaic birds are the long and completely isolated areas of New. Zealand and Madagascar. Among these curious birds, re- mains of which have been discovered in quite recent deposits (notably near ancient camping places of the aborigines, in caves, sand drifts and swamps) in New Zealand, may be men- tioned the Moas (Dinornis), the huge Raptorial bird Harpagornis, and a monster Goose. All these birds were flightless. It is round the Moas that most interest gathers, not only ORIGIN AND CHARACTERISTICS ii because their remains have been carefully studied by Owen and others, but their previous existence lingers in the traditions of the Maori people themselves, a race now almost as extinct as the huge birds with which it was contem- poraneous. Taking into account the compara- tively restricted area 'to which they were confined, these birds must have been not only numerous in species but in individuals ; whether these giant birds attained such a development in such narrow geographical limits is yet a moot question. Moas were either destitute of wings or possessed them in a rudimentary or functionless condition only. This helplessness unquestionably contributed to their rapid ex- termination when savage man appeared upon the scene. How long they lingered we have no reliable means of ascertaining, although Hutton considered that they became extinct between 300 and 500 years ago. Of little less interest are the extinct ^pyor- nithes of Madagascar, perhaps chiefly because they are generally believed to be the Rocs of Arabian romance. If this be so it shows how even the wildest fable may rest upon a more or less complete foundation of fact. Even to this day some of the inhabitants of that African 12 THE STORY OF THE BIRDS island cherish the behef that these birds still exist, and attribute to them (which of course is fable pure and simple) the power of flight. The first definite indication that such huge birds had formerly lived in Madagascar was the discovery of their colossal egg-shells, supplemented after- wards by the finding of bones. These remains have been referred to no less than five species, some however of which belong to birds of much smaller size. One of these large egg-shells is now in the British Museum, and measures some thirteen inches in length by nine and a half inches in breadth ; whilst a still larger example was formerly in the possession of the late Dawson Rowley. The flightless and consequently help- less condition of these stupendous birds must soon have led to their complete extermination after man appeared in the island. The second point to which I specially want to refer is the occurrence in the Miocene de- posits of Europe of certain genera of birds that in our time are strictly confined to the Tropics. Among the most remarkable of these may be mentioned the remains of Psittacus (a genus of Parrots), a form of Swift (Collocalia) now confined to the Tropics, a Secretary Bird (Serpentarius), what appears to have been a ORIGIN AND CHARACTERISTICS 13 Hornbill, a Plantain-eater (Necrornis), an Adju- tant (Leptoptilus), certain forms of Cuckoo (Centropus), and Trogons (Trogonidae). By most zoologists the presence of such species in Europe is taken as an indication that the climate at that time was much warmer than it is now, or even of a tropical character. This may or may not have been the case ; but to suggest that these birds (now only found in warm latitudes) were driven south by the cooler climate of the succeeding Pliocene era, or the intense cold that characterised that of the Glacial Epoch, is not, in my opinion, a correct interpretation of the facts. I maintain that one of the laws of dis- persal is that species never retreat from adverse conditions of life. All such species that during later Tertiary time had spread north and east from southern and even equatorial bases, and become sedentary in the warm equable climate of Euro-Asia must have been completely ex- terminated by the advent of adverse conditions of life, primarily due to a change of climate. Let it then be clearly understood that these avine types now^ extinct in Europe did not originate there during the long-continued warm climatic conditions of the later Tertiary Period, that they did not at the approach of a cooler 14 THE STORY OF THE BIRDS climate retreat southwards towards the Tropics, but that they originally extended their range northwards from southern bases where the generic roots of such forms exist to-day, not- withstanding the fact that a glacial catastrophe exterminated all these northern offshoots of which a few scattered relics have been dis- covered. The lesson then briefly summarised that all Ornitholites convey is that existing birds — birds as we see and know them to-day, have descended in a direct line from ancestors which differ more and more widely from living types the farther we trace them back into the remote past, until we are confronted by those semi-reptilian forms which appear to be the earliest progenitors of the great and now highly specialised avine group. Having thus briefly glanced at the origin of birds let us pass on to a consideration of the most salient points in the structure and char- acteristics of existing forms. Commencing with external features, a bird, as we have already stated, is known by its feathers. What are feathers, those wondrous things with which all birds are clothed, the chief vehicle of their matchless beauty, the bearer of those glorious sheens and tints and hues that single out this ORIGIN AND CHARACTERISTICS 15 class of creatures as the most attractive of organic beings ? Feathers, with the skin in which they grow, form the integument of a bird, and are classed with hairs, bristles, metatarsal scales, spurs, claws, and bill sheaths as epidermal structures. Probably many readers may think that feathers grow from ^11 parts of a bird's skin, but such is not the case (with almost the sole exception of the Penguins, Screamers, and Ratite birds such as Ostriches). The feathers of a bird grow in various tracts or well-defined patches, technically called pterylae, the spaces between these tracts, whether covered with down or absolutely naked, being known as apteria. These feather tracts are known as the pterylosis or pterylographie of a bird, and as they vary a good deal in their pattern or direction in the several groups, their study is of some importance to the ornithologist in his efforts to form a natural classification of birds. Feathers not only grow upon the newly formed chick, but at certain intervals of time upon the adult bird, when they are renewed either to replace acci- dental loss, or at the seasons of the moult when the old plumes are shed or pushed out by an entirely new set. We may define feathers then as horny products of the epidermal cells of the i6 THE STORY OF THE BIRDS skin which collectively form the covering of a bird and enable it to fly. A feather, generally speaking, consists of the following parts : A, the barrel or quill, calamus ; B, the principal shaft, rhachis ; C, the secondary or aftershaft, hypo- rhachis ; D, the web composed of a regularly arranged series of fibres or barbs, rami^ attached to which are a double series of barbules or radiiy which again in their turn give rise to barbicils or cilia, which latter generally end in booklets, hamuli. These latter it should be remarked are of very great importance, because they serve to interlock or join the barbules and barbs together, and thus serve to render the surface of the flight feathers almost impervious to air. Feathers may be roughly divided into three classes ; viz. contour feathers, down-plumes, and filoplumes. The first are not only the largest but perhaps the most important. They are those that appear nearest the surface, and therefore form the outline or contour of the bird's figure. They reach their greatest development of course in the wings (remiges) and tail (rectrices). In some of these feathers the cilia, and consequently the hamuli are wanting, thus forming the disconnected webs and decomposed plumes which are displayed as ornaments or decorative tufts in so many birds. ORIGIN AND CHARACTERISTICS 17 In other of these contour feathers the barbs are absent altogether, the rhachis being webless ; as in the wing quills of the Cassowary, the rectrice wires of certain Birds of Paradise, and in most of the tail-feathers of the Lyre Bird ; whilst the same remarks apply to the rictal or gape bristles with which so many birds are furnished, and the eyelashes of such birds that possess them, as the Hornbills. In some species the tip of the rhachis, as for instance in the neck hackles of certain Galline birds, and in some of the wing and tail feathers of the Waxwings, is expanded into wax-like modifications or processes. The down- plumes, as their name suggests, are softer in texture than the contour feathers by which they are hidden, are present in greater numbers, but are smaller. In these feathers the booklets (hamuli) are wanting, and the rhachis or shaft is often absent, the barbs sprouting from a stunted calamus. In connection with this type of feather mention should be made of those highly curious down -plumes known technically as ^^powder- downs." They derive their name from the fact that the slender tuft-like barbs and barbules of which they are composed are continually dis- integrating or crumbling at the tips into fine powder. Powder-downs in some birds grow B i8 THE STORY OF THE BIRDS over almost the entire body, not only on the bare places between the contour feather tracts but amongst these feathers themselves. In other birds they are confined to certain spots or are developed in well-defined pterylae. These peculiar feather growths are by no means common to all birds, only appearing in certain groups. Some of the most notable of these are the Herons and Bitterns, the Parrots, the Tinamous, a few of the Birds of Prey (Blue-winged Kite, Harriers), the Frog-mouths (a group of Goatsuckers), and some of the Rollers. The archaic character of these powder-downs seems indicated by the fact that only in a single genus (Artamus) of the extensive and highly specialised group of Passeres are they known to occur. Lastly we have to notice that peculiar kind of feather which is known techni- cally as a filoplume. A filoplume is composed of a short barrel (calamus) terminating in a slender hair-like shaft (rhachis), carrying few or no barbs (rami), and forms what is popularly termed an aftershaft, technically called an hyporhachis (already alluded to in describing the various parts of a feather). This filoplume starts from the base of the quill and varies a good deal in the degree of its development in the different avine groups. It becomes specially small in the ORIGIN AND CHARACTERISTICS 19 Passeres, almost absent in the Pigeons, Wood- peckers, Owls and so on, but is as large as the main rhachis in the Cassowary and the Emu. The aftershaft is generally concealed by the contour feathers, but in some cases it extends beyond them in the form of long slender filaments or hairs on the neck or back. The Blackbird furnishes a familiar example of a species pos- sessing these nuchal hairs, whilst some of the Bulbuls in the genus Tricholestes may be cited as notable instances of the latter. Some of the Warblers and Finches also exhibit them ; whilst the white thread-like filaments displayed by Cormorants are apparently another form of filoplume. It may be mentioned that the soft downy covering of so many young birds re- sembles the down-plumes of adults, although it differs in certain respects, notably in the abortive or even absent shaft, the absence of cilia, the filamentous rami, and with one exception the absence of an aftershaft. But these are details of far too technical a character to be dealt with in a work aiming above all things to be popular, and must be left to the more advanced student of birds. Having thus briefly dealt with the distribution, structure, and growth of feathers, it now becomes 20 THE STORY OF THE BIRDS necessary briefly to glance at the colour with which they are adorned. This too is a most complicated subject, and one which we can only deal with here in a cursory way. In the first place, to what is the colour of a feather due ? Colour is due either to pigment or to peculiarity of structure, or to both these causes combined. These three causes may be thus briefly sum- marised. In the first place colour may be pro- duced by pigment, either in a diffused solution or in the form of pigmented corpuscles. Colours produced in such a way are constant in the sense of not varying in tint in whatever position the light may fall upon them or the eye may view them. These colour pigments are firstly black (Zoomelanin), secondly red (Zoonerythrin), thirdly yellow (Zooxanthin), and fourthly and fifthly peculiar pigments, red (Turacin) and green (Turacoverdin), only known to be present in the plumage of the Plantain-Eaters (Musophagida3). Brown, it may be remarked, is a combination of black and red ; white is not due to pigment, but the appearance of such a feather is due to the countless spaces between its molecules which diffract and reflect the light. The remarkable gloss, irrespective of colour, on so many feathers is due to their highly polished surface. In the ORIGIN AND CHARACTERISTICS 21 second place we have colour arising from a pig- ment in combination with the overlying colourless structures in the form of irregular longitudinal ridges or pol3^gonal bodies, between the surface of the barbs and barbules and the pigment. When the polished surfa(Je of such feathers is scratched or held up against the light only the colour of the pigment is visible. This is the case with many blue, yellow, orange, and green feathers. In the third place we have those wonderful prismatic or metallic colours, of which the radiant Humming-Birds offer the most striking example. In these feathers a black or blackish-brown pigment rests below a transparent colourless layer, the surface of which may be either smooth and polished, covered with longi- tudinal ridges or sprinkled with innumerable pits, which serve as a series of prisms or facets, and change the colour of the feathers according to the direction from which the light falls upon them. It is interesting to know that these prismatic colours change their hue in the same order as those in the rainbow. When the light glides in a vertical direction over the surface of all these metallic feathers, the luminous rays are absorbed and they appear black. But, as Martin observes, respecting the plumage of Humming- 22 THE STORY OF THE BIRDS Birds, it is no longer the same when the Hght is reflected from these feathers, each of which performs the office of reflector. Then it is that the aspect of the emerald, the ruby and so on, varying with the utmost diversity under the incidences of the rays which strike them, is given out by the molecular arrangement of the barbules. It is thus that the gorget of many Humming-Birds takes all the hues of green, and then the brightest and most uniformly golden tints, down to intense velvet-black, or, on the contrary, that of ruby, which darts forth pencils of Hght, or passes from reddish orange to a crimson-red black. A few words on abnormal colouration must conclude this portion of the subject. Possibly the most familiar form of Heterochrosis is Albinism. I dare say every reader can recall a partial or complete instance of such a form of abnormal colouration, say in the Blackbird or the Pheasant, to quote the most familiar species. This is due to the absence of black pigment. Perhaps the next most famihar form of excep- tional colouration is that which is technically known as Melanism. This is exactly the reverse of albinism, and is caused by an excess of black pigment which renders the feathers abnormally ORIGIN AND CHARACTERISTICS 23 dark in colour. Less familiar forms of Hetero- chrosis are Xanthochroism and Erythrism, in which an abnormal amount of yellow or red pigment is present. In some cases at least (especially of the latter form) this is the result of exceptional food. Lastly, the arrangement and pattern of colour upon feathers demands a few words of explanation. These to a great extent are due to age, sex, or season. In many species spots and streaks are a sure indication of youth or immaturity, just as transverse bars, on the other hand, are characteristic of the adult stage of existence. In some highly specialised groups (as for instance the Crows) there is but little difference in colour between the nestling and its parent, but in other groups (as for instance the Gulls) several years may elapse before the young finally get rid of their characteristic dress of youth and assume the very different tints of the adult, during this period between youth and maturity practically recapitulating the ancestral changes the species has undergone, it may be from a mottled or spotted form to unsullied grey and white, as in the Gulls and Terns. In a great many birds the male is the most brilliantly coloured, and remarkable for those wonder- ful modifications of plumage that are classed 24 THE STORY OF THE BIRDS amongst secondary sexual characters. There are, however, one or two exceptions to this rule, the Phalaropes, the Dotterel, and certain Parrots furnishing us with instances in which the female is most brilliantly adorned. The colour of a bird's plumage in a great many instances varies considerably according to season, and in some cases great difference is produced by a long fringe of barbicels that conceal much of the conspicuous tints on the rest of the plumage, and which abrade and drop off as the breeding season approaches, but these matters are perhaps best dealt with when we come to consider the moulting of birds. Incidentally we may remark that the Snow-Bunting and the Brambling present us with two capital instances of this peculiarity. The correlation of colour with en- vironment is another branch of this interesting subject. Most readers may recall how birds of white plumage usually live amongst snow-clad localities, as for instance the Snowy Owl and the Ptarmigan ; how others that dwell in deserts and on sandy plains are clothed in plumage in which brown or yellow predominates ; how so many forest-haunting species such as Parrots, Fruit Pigeons, Barbets, and so on, are of tints in which green largely prevails. These are in most ORIGIN AND CHARACTERISTICS 25 cases modifications of colour for purposes of concealment, whilst yet another branch of this fascinating subject of animal colouration deals with the curious phenomena of Mimicry (in birds the known instances are comparatively few) and with recognitory and warning colours. (Conf. Curiosities of Bird- Life ^ Chaps, vii. viii.) We cannot well leave the interesting subject of plumage without devoting a few lines to the moulting of birds. Moulting is the changing or renewal at stated periods of the old abraded and worn feathers, these being shed and re- placed by new ones. Every living bird is sub- ject to this process at least once every year, a complete change of dress usually taking place shortly after the breeding season is over. In addition there are many birds that undergo a complete moult twice in the year, in spring and autumn ; others which have a partial moult in spring as well as the full moult in autumn ; whilst others, yet again, may almost be said to be in a chronic state of moult throughout the year. Birds with a double or partial spring moult undergo this just previous to the nuptial season, then acquiring those various wed- ding ornaments for which so many species are famous. So far as concerns the smaller contour 26 THE STORY OF THE BIRDS feathers moulting is a slow and gradual pro- cess, and as far as is known with little or no stated order of sequence, although I have re- marked in not a few species that the feathers of the head are the last to be changed. The flight feathers of the wings, and those of the tail, are shed and renewed in pairs, in most cases, so that the bird shall not be incon- venienced or incapacitated from flight during the process. In some groups, however, especi- ally in the Swans, Geese, and Ducks, the wing quills are shed rapidly and all, practically, at once, so that the birds cannot fly until the new feathers have grown. The Grebes, some of the Rails, and the Flamingo furnish others. During this period of comparative helplessness the birds skulk amongst dense cover, or repair to the sea or other open expanses of water, whilst the males of many species of Ducks dis- card their showy plumage at this time, acquir- ing a dress very similar in colour to the female, which they wear for some weeks until able to fly again. Incidentally we may remark that one species, the Logger-headed Duck, Tachyeres cinereus of Patagonia, never seems to regain the power of flight after the first moult of its wing quills. Young birds, generally speaking, ORIGIN AND CHARACTERISTICS 27 are later in their moult than adults, and in a great many cases the first set of quills are re- tained during the first year of existence, although in not a few Gallinaceous birds, which are able to fly before fully grown, rfew sets of quills are acquired as maturity is reached. Among birds that moult very slowly, or that are in a chronic state of plumal change, may be mentioned the Swifts, the Birds of Prey, the Herons, and the Ptarmigan. With the exception of the latter, which by the way dons no less than three distinct plumages in the year, all these birds appear to be moulting their wing quills very slowly throughout the year save perhaps in the breeding season. Some of this change of colour, due to season, is produced by an actual change of pigment and not by a replacement of the feather. (Conf. Stray Feathers, p. 154, for ad- ditional details respecting the moulting of birds.) Before leaving this portion of the subject we may briefly allude to another periodical change which takes place in the integument of certain birds. This relates to the peeling or shedding of the claws in some of the Grouse during spring, the elongation of the bill in the Redpoles during summer (possibly due to a change of food), the shedding of a horny projection from 28 THE STORY OF THE BIRDS the ridge of the bill (assumed by both sexes during the breeding season), by the American White Pelican, this peculiar excrescence strewing the breeding ground of these birds literally in bushels; and lastly the curious annual moult which the bills of some of the Auks undergo as well as the acquisition and shedding of the horny or fleshy growths above the eyes and round the gape. Our own familiar Puffin furnishes a most interesting instance of this phenomenon. Some very interesting details of this peculiar form of moulting amongst the Alcidae are published by Dr. Stejneger in Bul- letin No. 29 of the United States National Museum. We will now proceed to a brief consideration of the most salient characteristics of the skeleton and internal structure of birds. Of course in a work of the present scope it is not only im- possible but unnecessary to enter into any great detail of avine anatomy. The student must seek such information in special works, one of the most useful being Professor Newton's Dictionary of Birds ^ Dr. Gadow's contributions to which upon this subject being singularly full and original. To these contributions we are largely indebted for the following particulars ORIGIN AND CHARACTERISTICS 29 relating to the osteology and digestive system of birds. The skeleton of a bird may very naturally be divided into three principal parts, comprising the head, the trunk, and the limbs. The vertebral column not only contains and serves as a protection to the spinal cord, but supports the head and limbs. It is composed of a very variable number of units or vertebrae, which are divided according to the position they occupy into the following classes, viz., cervical relating to the neck, dorsal to the back, sacral or pelvic to the loins, and caudal to the tail. The first cervical vertebra is termed the Atlas, because it bears the head, and which is articu- lated with it by a single occipital condyle. The second, termed the Axis, because it is the pivot on which the atlas and head turn, is consider- ably longer and larger than the succeeding cervical vertebrae, remarkable for their paired or single ventral processes and vertical knobs, when in the former condition assisting to pro- tect certain blood-vessels, and when in the latter serving for the attachment of the powerful muscles which work the flexible neck. Suc- ceeding these come the dorsal vertebrae, which not only in many cases coalesce with each other, but always do so with the sacral or pelvic 30 THE STORY OF THE BIRDS vertebrae, and nearly always with the terminal portion of the caudal vertebrae which, fused to- gether, form the Pygostyle or terminal triangular plate in which the rectrices or tail-feathers are carried. A typical avine vertebra consists of the centrum, an arch, and two ribs. The arch as already stated encloses and protects the spinal cord. This type of vertebrae, with the facets or articular surfaces saddle-shaped, is termed hetero- coelous, and is restricted to Birds. The ribs of a bird are attached to the vertebrae firstly by a capitulum or head, and secondly by a knob or tuberculum. That portion next to the head is termed the neck, and this is succeeded by the shaft, composed of two pieces, the dorsal and the ventral. To the posterior margin of the dorsal section is generally attached a thin bony blade termed the uncinate process. This pro- cess is attached to the ribs (with the exception of the last) of all birds (save the Screamer), and is also present in some reptiles. When the ventral section reaches and articulates with the sternum, the rib is a "true" one; but if the sternum is not reached it becomes a *^ false" rib. Ribs according to their position are classified as follows : cervical, cervico-dorsal, thoracic, and lumbar. The number in these ORIGIN AND CHARACTERISTICS 31 various classes varies considerably, not only amongst species but even in individuals — a fact which renders them of no value from a taxonomic point of view. We now come to a consideration of that pa^t of the skeleton technically called the sternum, or in more familiar language the breast-bone. This very important part of the avine frame is joined to the vertebral column, as we have already seen, by the thoracic ribs, whilst its anterior margin supports the coracoids, or strong bones con- necting it with the scapulae or shoulder-blades and the clavicles or collar-bones, the three pairs of bones combined forming the Pectoral Arch or shoulder girdle. The last-named are generally united or fused at the ventral end, into a V-shaped Furcula, much better known as the *' wish-bone " or ^' merry-thought." The furcula is subject to considerable modification in certain birds, notably in the Crane, the Swan, and the Frigate Bird ; in other birds the clavicles are degenerated, the dorsal portion alone being retained, the ventral end being reduced to a ligament. In some birds (the Parrots for in- stance) the clavicles are absent. In many instances the furcula is ossified with the anterior portion of the keel of the sternum ; whilst in 32 THE STORY OF THE BIRDS Ratite Birds, the Frigate Bird, and the now extinct Dodo the coracoids and the shoulder- blades are fused together. Two very distinct types of sternum exist. Of these by far the most generally prevailing is that in which the ventral surface is provided with a ridge or keel (carina). The other type of sternum is that in which the keel is absent, more resembling a flat- bottomed boat (ratis). This latter is found in a few archaic types only, such as the Ostrich, Rhea, Cassowary, Emu, and Kiwi. Birds with a keel to the sternum are therefore termed Carinate Birds, whilst those in which this ridge is absent are called Ratita Birds, these groups forming the two divisions into which all living birds are separated by systematists. Before leaving the sternum we have to allude to the various pro- cesses on the sides behind the articulation of the ribs. The most noticeable of these are situated near the posterior portion, and consist of outgrowths (although connected by mem- branaceous tissue), giving the margin when macerated a more or less deeply notched ap- pearance, or when the extremities are joined or enclosed by bone or cartilage they form what are technically termed fenestrac. In some birds two of these notches on each side of ORIGIN AND CHARACTERISTICS 33 the posterior margin of the sternum occur, in others but one. These peculiarities appear to possess little taxonomic value, the configuration of the anterior portion of the sternum being more important in this respect. The next por- tion of a bird's skeleton that we have to consider is the pelvis, composed of a number of fused vertebrae together with three bones on either side, the largest and most dorsal of which is called the Ilium, the ventral or middle one termed the Ischium, and the anterior and most slender of all known as the Os pubis, and all meeting at the acetabulum or cup of the pelvis in which the head of the femur or thigh-bone articulates. These three paired bones coalesce with each other at an early stage of the bird's existence, whilst the notch between the two first named of these bones becomes a foramen in all known birds with the exception of the archaic Ratitae and Crypturi. From the trunk of the skeleton we now pass to a brief notice of the bones of the limbs. We will take those of the wings or anterior limbs first. These consist of the Humerus or upper arm- bone which articulates with the coracoid and scapula, the Ulna and Radius which together compose the forearm, and the Carpus or wrist, 34 THE STORY OF THE BIRDS the Metacarpus or space between the wrist and the digits, and the Digits or fingers, the three sets together forming the hand. The first and shortest of the three metacarpals (together forming the metacarpus) bears the thumb or Pollex (to the basal joint of which the bastard wing is attached), consisting of one or two joints (the terminal one frequently absent or aborted) ; the second and strongest composed of two or three joints is termed the Index ; whilst the third, the weakest and most slender, has one joint only. Some few Archaic birds (Ratitae) possess the second metacarpal only ; whilst in the Penguins it is fused with the first. Claws at the tips of the metacarpals are rare in existing birds, although as we have already seen the extinct Archaeopteryx was provided with them. In modern birds they apparently mostly appear accidentally upon the thumb and index, and probably in no case are functional. We have seen a pollex claw upon the Common Whitethroat, and such is found in various Anserine birds, in the fowl, and in some Raptorial birds. Conical spurs are not un- common on the carpal and metacarpal bones, and are often used as weapons. The bones of the legs or posterior limbs, like ORIGIN AND CHARACTERISTICS 35 those of the wings, are composed of three prin- cipal portions. The first of these is the Femur or thigh, which, as we have already mentioned, articulates with the cup or acetabulum of the pelvis, following which come the Tibia and Fibula, often more or less coalescent and together forming the shank or '' drumstick," and lastly the bones of the Foot. Not a little confusion exists, even amongst persons fairly familiar with birds, respecting these three divi- sions of a bird's leg. The actual thigh of a bird is hidden by the plumage, and the shank (Tibia and Fibula) is often mistaken for it, as the metatarsus is for the shank. The metatarsus is a compound structure formed by the fusion of the second, third and fourth metatarsal bones, which when maturity is reached do not lie in the same plane (except in the Penguins and some Parrots), the third having its upper end thrust backward and its lower end pushed forward during the course of growth. The fifth metatarsal is only seen in the embryotic stage, soon disappearing, whilst the first meta- tarsal chiefly remains separate, lying in the majority of birds behind the distal part of the others. The metatarsus is covered with a series of angular horny plates or scutellae, varying 36 THE STORY OF THE BIRDS considerably in size in the different groups, in some consisting of a series of fine reticulations, in others of oblong plates, or of both combined, whilst in others yet again the surface of the metatarsal is smooth and ^^ booted." Following the metatarsals come the toes, which form that part of the foot upon which a bird stands or walks. Owing to the transitory character of the fifth metatarsal a bird never shows any trace of a fifth toe. The first toe in not a few cases is aborted, in the Ostrich the second toe is want- ing, whilst in two genera of Kingfishers the second toe is aborted : the only instance known of an aborted fourth toe is presented by the Timeliinae, genus Cholornis. The hind toe (Hallux) has two joints or phalanges only, the second toe or digit possesses three, the third toe four, and the fourth toe five joints. The Swifts, however, are excep- tional, having only three phalanges in each of the anterior toes, whilst in the typical Goatsuckers and the Sand-Grouse the fourth digit possesses only four. The toes of birds are modified in an immense number of ways to bring them into harmony with the conditions of life and the various habits of their possessors. In numbers of birds either the hallux or the fourth digit is reversible at will, as in the Owls and to a lesser ORIGIN AND CHARACTERISTICS 37 extent in the Plantain-Eaters and certain forms of Rollers. In other groups this temporary con- dition has become permanent, and we have what is termed a ^' zygodactylous " foot, as presented by the Woodpeckers, Cuckoos, and Parrots. In the Mouse Birds (Colius) the hallux can be brought forward whilst the fourth digit can be turned backwards at will, whilst in some of the Swifts and Goatsuckers all the digits constantly turn forwards, this class of foot being techni- cally called a ^^ pamprodactylous " one. In many water birds the anterior digits are joined together by a membrane, thus forming what we call a webbed foot, so admirably adapted for swimming, whilst in the Pelicans the hallux is also joined to the other digits by a web. The hallux is by far the most variable of the digits, and may either exist on the same plane as the other digits, when it is usually large and of service, or be raised above the others, and is then smaller and without function. This is especially the case in the Wading Birds, in others it is reduced to a mere stump as in the Petrels and certain three-toed Woodpeckers, and in others it is entirely wanting, as in the Auks, Bustards, Ostriches, and allied birds (Ratitae), and one or two Waders (Sanderling, Grey 38 THE STORY OF THE BIRDS Plover). The inner margin of the claw on the third toe or digit of some birds is toothed, serrated, or pectinated as in the Goatsucker, the Herons, the Cormorants, the Coursers, Pratin- coles and some of the Grouse. From the trunk and limbs we pass to the head or rather the skull, the last portion of the avine skeleton we have now to consider. The complicated nature of this part of the skeleton and the large amount of space that would be required to render its description at all intelligible to the average reader, make a detailed notice of the numerous parts here im- possible. The student or interested reader may therefore be referred to some standard work on vertebrate anatomy (such as Owen's, or better still the masterly contributions of Dr. Gadow to Professor Newton's Dictionary of Birds\ where full particulars may be obtained. The various bones of the head, it may be stated, fall naturally into several groups, as, for instance, those forming the Cranium, which includes all the bony and cartilaginous parts of the skull except the jaws and the palato-pterygo-quadrate bones, those appertaining to the visceral arches which give rise to the Hyoid Apparatus, the palate and the jaws. The Bill lends itself to ORIGIN AND CHARACTERISTICS 39 more popular treatment, and is so closely con- nected with the habits and characteristics of birds that some amount of