[Transactions of the New Zealand Institute, Vol. XXVII.]

Art. III.—Illustrations of Darwinism; or, The Avifauna of New Zealand considered in relation to the Fundamental Law of Descent with Modification.

By Sir Walter L. Buller, K.C.M.G., D.Sc., F.R.S., &c.

[Read before the Wellington Philosophical Society, 27th June, 1894.]

On my retirement from the chair last year I had to apologize for my inability, owing to my hurried departure for England, to prepare the usual presidential address, but I then promised to deliver it later on; and by the courtesy of Major-General Schaw I am enabled to do so this evening in the form of a paper.

The Turks have a proverb which says that "the devil tempts the busy man, but the idle man tempts the devil." Bearing this in mind, I employed myself during a portion of my last six weeks' voyage from England in gathering together from my New Zealand notes and recollections, and carefully elaborating, certain facts and inferences that appear to me to bear directly on the great doctrine of the evolution of species by a natural process of descent with modification—that is to say, the ever-operating law of natural selection by variation and the survival of the fittest. And, as I must to-night take up some special subject for my address, it seems to me that I cannot perhaps do better than place before you, whilst the matter is fresh in my memory, the facts and considerations that presented themselves to my mind and the conclusions arrived at in the course of this interesting study. I do so the more readily because I find that the distinguished and gallant officer who succeeded me, and who still occupies the presi- page 76 dential chair, in his inaugural address on the 14th June last, placed before the Society, in very picturesque language, views on this question of evolution which, in the light of modern science, I cannot but regard as unorthodox and, if I may use the term, pernicious. Major-General Schaw will not, I am sure, object to this personal reference, because in concluding his address he frankly admits that he has "thrown down the gauntlet and opened the door to criticism and discussion." I will give just one quotation by way of illustration. The President says, in his address, "In connection with these beetles I would refer to one passage in the Manual, and employ it as my text in what I wish to say on evolution, as it is in accordance with the theories of evolution which are now very generally accepted. The passage I refer to is at page 23, where this swimming-beetle is said to be 'only what a ground-beetle might naturally become if forced to lead an aquatic existence.' Now, my imperfect observation leads me to believe that any ground-beetle now forced to lead an aquatic existence—i.e., being put into water—will not become a swimming-beetle, but, if it cannot get out, will inevitably become a dead beetle." Now, it seems to me that such a passage as that is worthy of the Dark Ages of Science. At any rate, it shows that the author of it has utterly failed to appreciate the plan and method of Natural Selection, for his argument entirely ignores the necessary postulate of Time. It is true that, later on in his address, he says, "We may undoubtedly accept as a working hypothesis, which has very strong arguments in its favour, that the remarkable unity in structural design which we discern in the animate world has been brought about in some way through j heredity, or natural descent, with variations"; and, in commenting on the complete correspondence in all essential features between the Scriptural account and the facts of nature, he acknowledges that "Science fills out the pictures with endless and wonderful details, and teaches us that the days of creation were not days of twenty-four hours, but of many thousands of years." But here I fear his faith is weak; for, instead of limiting the Mosaic "days" to thousands of years, science claims space for vastly extended epochs of time. Sir Charles Lyell computes the age of the world, since the Cambrian period, at 270 millions of years, and in the opinion of most geologists this is a very moderate estimate. And Darwin says, "If the theory [as to the formation of the stratified rocks] be true, [unclear: i] is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed, as long as, or probably far longer than, the whole interval from the Cambrian age to the present day, and that during these vast periods the world swarmed with living creatures."

Before proceeding to my subject, I may refer incidentally page 77 also, to a paper by one of our members, Mr. Coleman Phillips, "On a Common Vital Force," which appears in the last volume of our "Transactions." This essay affords pleasant and amusing reading, but it is impossible to take it seriously. For example, when a writer, professing to deal scientifically with his subject, brackets together the Moa and our domestic fowl—a Ratite bird with a Carinate—as "one species alone of living things," there is an end to any attempt at rational discussion. Mr. Coleman Phillips, in this paper, admits that he has not yet finished reading Darwin's "Origin of Species," but says, "What I have read has filled me with pain," and he proceeds to treat in a slighting spirit a book which, in the vigorous language of Professor Newton, "has effected the greatest revolution of human thought in this or perhaps in any other century."^* For my own part, I regret, as well for the author's sake as for the credit of the Society, that such a paper was allowed to appear in the "Transactions." With these introductory remarks, for clearing the ground as it were, I shall proceed to discuss the subject which I have selected for my theme this evening.

The ornithology of New Zealand, apart from its intrinsic interest, presents to the thoughtful naturalist several aspects of great philosophical significance. Not the least of these is that of the many peculiar forms which it contains, and their local distribution, because of the remarkable evidence hereby furnished in support of the now generally accepted Darwinian theory of the creation of species in the organic world—that is

^* "The theory of evolution was started as an hypothesis by Buffon, and defended and modified by Lamarck and others, but was regarded by most scientific men as a wild dream, until Darwin and Wallace, after years of patient accumulation of materials, overwhelmed the learned world with such a vast array of facts that with scarcely an exception scientific men acknowledged their defeat, and the hypothesis of evolution was raised to the rank of a theory as firmly based on facts as Newton's theory of gravitation, or the undulatory theory of light. . .. . .. The great charm of Darwin's theory of natural selection is its simplicity. The theory of evolution by descent with modification had a great deal to recommend it; but the difficulty always presented itself, By what possible machinery could it be worked? To suppose a special creation of every species was bad enough, and looked weak, as if the clock always wanted mending or altering to make it go right. But to suppose not precisely a special creation, but a special interference, in a given direction, with the law of like producing like, at every generation, was a thousand times worse; and, consequently, of two evils scientific men chose the least, and the theory of evolution was laid on the shelf until Charles Darwin and Wallace took it down again. The fact of the survival of the fittest in the struggle for existence is such a simple theory that a child can understand it; and not only the scientific world, but almost every educated man, accepted the new theory of evolution as soon as they saw—or thought they saw—the simplicity of the machinery by which it is worked."—Seebohm

page 78 to say, by a natural and gradual modification of character, due to the survival of the fittest in the universal struggle for existence.

The principle of natural selection is expressed by Darwin himself as that of "the preservation during the battle of life of varieties which possess any advantages in structure, constitution, or instinct." He says, and with great force, "In scientific investigations it is permitted to invent any hypothesis, and if it explains various large and independent masses of facts it rises to the rank of a well-grounded theory. . . . If the principle of natural selection does explain these and other large bodies of facts, it ought to be received. On the ordinary view of each species having been independently created we gain no scientific explanation of any one of these facts. We can only say that it has so pleased the Creator to command that the past and present inhabitants of the world should appear in a certain order and in certain areas; that He has impressed on them the most extraordinary resemblances, and has classed them in groups subordinate to groups. But by such statements we gain no new knowledge; we do not connect together facts and laws; we explain nothing."^* In his "Origin of Species" Mr. Darwin has shown that all organic beings, without exception, tend to increase at a very high ratio, and that the inevitable result is an ever-recurrent struggle for existence, in the natural course of which the strongest ultimately prevail and the weakest fail. By this process those variations, however slight, which are favourable are preserved or selected, and those which are unfavourable are destroyed. This continued production of new forms through natural selection inevitably leads to the extermination of the older and less improved forms, these latter being necessarily intermediate in structure, as well as in descent, between the last-produced forms and their original parent species. The position to which this brings us is thus stated: "Now, if we suppose a species to produce two or more varieties, and these in the course of time to produce other varieties, the principle of good being derived from diversification of structure will generally lead to the preservation of the most divergent varieties; thus the lesser differences characteristic of varieties come to be augmented into the greater differences characteristic of species, and, by the extermination of the older intermediate forms, new species end by being distinctly defined objects. Thus, also, we shall see how it is that organic beings can be classed by what is called a natural method in distinct groups—species under genera, and genera

^* "The Variations of Animals and Plants under Domestication," 2nd ed., vol. i., page 9.

page 79 under families." Following the subject up with consummate skill, and bringing together a marvellous array of facts and observations, Darwin has shown very conclusively that descent with modification has been from time immemorial the means, whether naturally or artificially it matters not, of producing new and distinct forms of animal and vegetable life. The subject is on the face of it a very attractive one, and, when we come to deal with the actual facts, there is room for almost endless speculation in all directions. But what I propose to do this evening is to single out some well-established features and peculiarities of the New Zealand avifauna, to which, as you are aware, I have for many years given special attention, and to consider their direct bearing on the theory of evolution, or, putting it the other way about, to endeavour to find in the Darwinian doctrine of natural development their true and rational explanation.

Perhaps there is no country in the world where the process of natural selection among birds has had so favourable a field for its operation as New Zealand, owing to its great age as a continental island, and to the entire absence of natural enemies, up to the time, at any rate, of its occupation by man and the introduction of domestic animals which afterwards became feral. As a result, what do we find here as representing the ancient order of Ratite birds? I will not refer at present to the Moa and its kindred, because these birds have become extinct, and, except by way of analogy, do not come into my present subject. But look at the genus Apteryx, taking, for illustration, the oldest known member of the genus, A. australis. Here is a bird with, so to speak, the body of a turkey and the wings of a sparrow, these limbs having become so dwarfed by the operation of natural laws that they are reduced to mere rudiments; yet all the muscular parts, aborted and atrophied though they be, become perfectly distinct under the dissecting knife. Unlike all other known birds, instead of having the nostrils placed in the nasal groove, or on the ridge of the bill (as in the Petrel family), they are situated under a terminal protuberance at the extreme end of the upper mandible; and on examination it is seen that the produced upper mandible is in reality a prolongation of the facial bones—the result, no doubt, of long-continued gradual development in that direction—the brain being pushed back, as it were, into a remarkably small cranial pan for the size of the bird. These modifications of structure are of course adaptations to the feeding habits of the bird, which subsists principally on earthworms, in search of which, aided by its power of smell, it probes the soft ground or loose vegetable mould in its forest haunts. In addition to this the head is furnished with long rictal hairs or feelers, as sensitive as the page 80 whiskers of a cat, and its hearing is known to be marvellously acute.

Mr. A. R. Wallace, in his admirable work on "Darwinism," says (at page 114), "So soon, however, as we approach the higher and more fully developed groups, we see indications of the often-repeated extinction of lower by higher forms. This is shown by the great gaps that separate the mammalia, birds, reptiles, and fishes from each other; whilst the lowest forms of each are always few in number and confined to limited areas. Such are the lowest mammals—the Echidna and Ornithorhynchus of Australia; the lowest birds—the Apteryx of New Zealand and the cassowaries of the New Guinea region; while the lowest fish—the Amphioxus or lancelet—is completely isolated, and has apparently survived only by its habit of burrowing in the sand. The great distinctness of the carnivora, ruminants, rodents, whales, bats, and other orders of mammalia; of the accipitres, pigeons, and parrots, among birds; and of the beetles, bees, flies, and moths, among insects, all indicate an enormous amount of extinction among the comparatively low forms by which, on any theory of evolution, these higher and more specialized groups must have been preceded."

Now, whilst accepting Mr. Wallace's general argument and admitting its soundness, I must venture to differ entirely with that distinguished scientist as to the position assigned to the genus Apteryx. I cannot for a moment admit that the Kiwi is one of the lowest birds in the sense implied. It rather seems to me to be an extremely specialized form, and one to which Mr. Wallace's own felicitous remarks (at page 105) are specially applicable: "In species which have a wide range the struggle for existence will often cause some individuals or groups of individuals to adopt new habits in order to seize upon vacant places in nature where the struggle is less severe. Some, living among extensive marshes, may adopt a more aquatic mode of life; others, living where forests abound, may become more arboreal. In either case we cannot doubt that the changes of structure needed to adapt them to their new habits would soon be brought about, because we know that variations in all the external organs and all their separate parts are very abundant and are also considerable in amount. That such divergence of character has actually occurred we have some direct evidence." By way of illustration, Mr. Wallace reminds us that Madeira, like many other oceanic islands in the temperate zone, is much exposed to sudden gusts of wind, and that, as most of the fertile land is on the coast, insects which flew much would be very liable to be blown out to sea and lost. Year after year, therefore, those individuals which had shorter wings, or page 81 which used them least, were preserved; till in process of time, as we now see, the insects of Madeira have become wingless and terrestrial, or, if they have not entirely lost their wings, have had them so reduced as to be useless for flight. To my mind it would not be right to confound these wingless insects with the lower forms of the "more generalized ancestors," but rather to assign them a place among the "higher and more specialized groups." For it must be borne in mind that, as Mr. Wallace himself expresses it (page 120), the "remarkable advance in the higher and larger groups does not imply any universal law of progress in organization, because we have at the same time numerous examples of the persistence of lowly-organized forms, and also of absolute degradation or degeneration. Serpents, for example, have been developed from some lizard-like type which has lost its limbs; and though this loss has enabled them to occupy fresh places in nature, and to increase and flourish to a marvellous extent, yet it must be considered to be a retrogression rather than an advance in organization. The same remark will apply to the Whale tribe among mammals; to the blind amphibia and insects of the great caverns; and among plants to the numerous cases in which flowers, once specially adapted to be fertilized by insects, have lost their gay corollas and their special adaptations, and have become degraded into wind-fertilized forms." But it seems to me that on this point Mr. Wallace is inconsistent with himself; because at page 481, after referring to my figure of the wing in vol. iii. of our "Transactions," he says, "Even in the Apteryx, the minute external wing bears a series of nearly twenty stiff quill-like feathers"; and he goes on to say, "These facts render it almost certain that the Struthious birds do not owe their imperfect wings to a direct evolution from a reptilian type, but to a retrograde development from some low form of winged birds, analogous to that which has produced the dodo and the solitaire from the more pronounced pigeon-type." He adds that our best anatomists agree that both Dinornis and Apteryx are more nearly allied to the cassowaries and emus than to the ostriches and rheas.^* Now, from this point of view, I think the language in which I long ago characterized the Kiwi—although challenged by Professor Hutton and others—is fully justified—namely, that it is the diminutive and degenerate representative of the ancient colossal forms of wingless birds.

^* At page 416, op. cit., Mr. Wallace says, "Whales, like Moas and Cassowaries, carry us back to a remote past, of whose conditions we know too little for safe speculation. We are quite ignorant of the ancestral forms of either of these groups, and are therefore without the materials needful for determining the steps by which the change took place, or the causes which brought it about."

page 82 Its very existence, as we now find it, is an illustration of the truth, as formulated by Wallace himself, that "greater swiftness, increased cunning, nocturnal habits, change of colour, or the power of climbing trees and living for a time on their foliage or fruit, may be the means adopted by different species to bring themselves into harmony with the new conditions; and by the continued survival of those individuals only which varied sufficiently in the right direction the necessary modifications of structure or of function would be brought about, just as surely as man has been able to breed the greyhound to hunt by sight and the foxhound by scent, or has produced from the same wild plant such distinct forms as the cauliflower and the Brussels sprouts."

I have referred to certain superficial characters; and for the purposes of our argument we need not at present go beyond these. The Apteryx then, I take, to be the most specialized type of its kind—an extreme form of degeneracy, using that term in its Darwinian sense. But, besides Apteryx australis, there are five other species, more or less distinct the one from the other, but all closely allied in every respect, size and colour being the only distinguishing characters. I will enumerate these species, with the ascertained range of each. Apteryx australis, already mentioned, inhabits the southernmost parts of the South Island; Apteryx mantelli (= A. bulleri, Sharpe) is spread over the North Island; Apteryx oweni (Gould) is met with in the wooded country in the northern and eastern portions of the South Island; Apteryx haasti (Potts) in the Heaphy Ranges and further south; Apteryx occidentalis (Rothschild) on the western slopes of the Southern Alps, and, curiously enough, in the Tararua Ranges on the west coast of the North Island; and, lastly, Apteryx lawryi (Rothschild) on Stewart Island.^* The dividing-lines be-

^* This is the same as Apteryx maxima of my paper (Trans. N.Z. Inst., vol. xxiv., pp. 91, 92). Mr. Walter Rothschild, in his revision of the genus (Ibis, 1893, pp. 573-576), says, "Apteryx maximus is almost a fictitious species, though I am inclined to agree with Professor Hutton that it was only an overgrown A. haasti. The name was published originally, without a description, by Bonaparte in the 'Comptes Rendus,' xliii., p. 841, taken from an unpublished manuscript of Jules Verreaux, and then Professor Hutton described a foot in his 'Catalogue of the Birds of New Zealand' and ascribed it to this species. Both references, however, distinctly refer to a bird from the South Island. In 1890 Sir Walter Buller finally announced that he had discovered the true A. maximus on Stewart Island, and I am fortunate in possessing the entire series from his collection; but I most emphatically say that this species cannot be A maximus of Verreaux, and therefore I have much pleasure in naming it Apteryx lawryi, after Sir W. Lawry Buller. Sir W. Buller fully described this bird before the Wellington Scientific Society. All that I shall add is, therefore, that, though the differences between it and A. australis are very slight, they are apparently constant, owing, no doubt, to the isolation of the species."

Mr. Rothschild declines to adopt Dr. Sharpe's proposed name of Apteryx bulleri for the North Island Kiwi, on the ground that the bird originally named Apteryx mantelli by Mr. Bartlett came from the North Island, which fact, in his opinion, "establishes, without a doubt, the priority of Mr. Bartlett's name." He says, further, "As regards A. mantelli, I can only point out that Dr. Otto Finsch maintained that Mr. Bartlett's diagnosis was founded on a false basis, and he, moreover, believed that the North Island Apteryx was barely worthy of sub-specific rank. Sir Walter Buller, however, and all other ornithologists who have expressed any opinion on the subject, maintain, and, I am convinced, rightly, that the North Island bird is distinct from A. australis."

page 83 tween these species, at certain points, are so indeterminate that ornithologists are not yet agreed as to how many independent species should be recognised. Dr. Otto Finsch, the well-known German scientist, contends that the North Island bird cannot be separated from Apteryx australis, except as a local variety, although in this view he now stands alone; Professor Newton, whose opinion always carries great weight with me, declares his inability to distinguish the former as a species distinct from Apteryx lawryi of Stewart Island, although he recognises Apteryx australis, which occupies an intermediate range of country. But the Professor is also in some doubt as to the propriety of admitting Apteryx haasti as a species.

Mr. Walter Rothschild, who owns the largest collection of Apteryges in the world (some thirty living birds, and I believe over a hundred skins), has, after mature consideration, decided to separate the spotted grey Kiwis into two species—Apteryx oweni (Gould) and Apteryx occidentalis (Roths.). Of the latter he possesses a living example, obtained in the neighbourhood of Milford Sound, nearly as large as Apteryx haasti and very different in appearance from Apteryx oweni, having banded plumage, a dark head, and blackish-grey feet. To this he refers Mr. Morgan Carkeek's example from the Tararua Ranges (North Island), and a number of specimens collected by different persons on the west coast of the South Island. Of the distinctness of his type I have no doubt whatever; but I am not quite prepared to follow him in uniting the others with it. They seem to me to be a form intermediate between it and the Little Grey Kiwi (Apteryx oweni) with which we are all so familiar. Here, in fact, we have an instance of the boundary-line between one supposed species and another being so indistinct as to occasion constant doubt and confusion in the discrimination of the forms.

Then, again, with regard to Apteryx mantelli, in the North Island. You are no doubt familiar with the chestnut-brown Kiwi which inhabits the Pirongia Ranges and is found all the page 84 way down the west coast to Wanganui. But all the specimens I have seen from the east coast are almost black in plumage, even the feet being blackish instead of whitish-brown as in the ordinary bird. So far no attempt has been made to raise this form to the rank of a species, or even of a subspecies; but the fact remains that the birds from this part of the country are always dark-coloured, and, as such, readily distinguishable from the common Kiwi. And, as I have mentioned in my "Birds of New Zealand" (vol. ii., p. 310), there is likewise a rufous-coloured form, with plumage of a very peculiar texture ("Kiwi-kura" of the Maoris), which I found breeding true in the Pirongia Ranges; but, as this bird inhabits the same district as Apteryx mantelli, it can only be regarded as a variety. Nevertheless it shows very clearly the latent tendency to vary.

Apteryx lawryi is the largest of these species, as Apteryx haasti (which is next in size) is the most handsome, owing to its chestnut-and-brown dappled plumage. Apteryx lawryi runs as it were in parallel lines with Apteryx mantelli and Apteryx australis, as Apteryx haasti does with Apteryx oweni and Apteryx occidentalis. But, whether all these species be accepted as distinct, or some of them be regarded as mere varieties of others (which will always be debatable ground), there can be no doubt whatever that they have all come from a common parent stock, and that within a period of time, geologically speaking, comparatively recent. Going back to earlier times, and reasoning by analogy, we may venture to infer that the remote ancestor of the degenerate parent form was a volant bird—probably one tolerably well furnished with wings and tail, with a proportionately large head and short bill, with the muscles of the posterior limbs far less developed than in the Kiwi, and with very different plumage, both as to form and texture.

It may be asked how it is that we find the Kiwi developing a long stiletto-like bill, whilst another race of wingless birds, the Moas, belonging to the same order and inhabiting the same country, were perfecting themselves in an entirely opposite direction. But it must be remembered that, according to the ascertained laws of variation, divergence of character in opposite directions may take place even among members of one and the same species, at one and the same time, and within the same geographical area. Isolation, for such a purpose, does not necessarily mean insulation, as some writers appear to assume. Wallace puts it very clearly: "Isolation will often be produced in a continuous area whenever a species becomes modified in accordance with varied conditions or diverging habits. For example, a wide-ranging species may, in the northern or colder part of its area, become modified in one page 85 direction, and in the southern part in another direction; and, though for a long time an intermediate form may continue to exist in the intervening area, this will be likely soon to die out, both because its numbers will be small, and it will be more or less pressed upon in varying seasons by the modified varieties, each better able to endure extremes of climate. So, when one portion of a terrestrial species takes to a more arboreal or to a more aquatic mode of life, the change of habit itself leads to the isolation of each portion."

Now, it is not difficult to imagine that in the case of a country which was gradually emerging from the depths of the ocean, presenting for long-continued periods of time low flats more or less covered with scrubby vegetation, available for purposes of concealment, a smaller size would be beneficial to the already practically wingless birds, the more so if correlated with a longer bill, for the purpose of hunting for annelids and insects in the increasing deposits of mould covering these newly-formed flats. And, bearing in mind that natural selection acts solely "by the preservation of useful variations, or those which are beneficial to the organism under the conditions to which it is exposed," we should in this case regard the so-called degeneration of the Kiwi as an improvement in the organism of the bird in relation to its conditions and environment. So also, in regard to those wingless birds which continued to inhabit the table-lands, and to subsist on fern-roots and the ever-present "cabbage-tree," should we regard a longer neck and a stronger bill as beneficial variations, especially if correlated with a more massive posterior development, such as that which distinguishes Dinornis elephantopus and Dinornis crassus. May not the giant Kiwi (Megalapteryx hectori), the remains of which were discovered and described by the late Sir Julius von Haast, represent one of the intermediate forms which have been stamped out and lost in the long-continued struggle for existence along the borderland, so to speak, of these different races of wingless birds?

As I have already stated, each so-called species of Kiwi is restricted in its range to a particular district. In the case of Apteryx mantelli and Apteryx lawryi this is insular, save as to the appearance of the Grey Kiwi on the Tararua Range, which I shall presently endeavour to account for. Now, if any sudden catastrophe were to overtake New Zealand, destroying all animal life, the remains of the different species of Kiwi (so far as they could be distinguished) would be found in different localities and never commingled. This is not the case with Dinornis and its allies. The bones of about a thousand birds were exhumed by Sir Julius von Haast from the Glen-mark marshes, and these comprised the skeletons of several page 86 genera and numerous species, varying considerably in stature, all mixed up indiscriminately together, showing that these birds had inhabited the plains of Canterbury at one and the same time. I have endeavoured to furnish an explanation of this in my introduction to "The Birds of New Zealand," pages xxxiv., xxxv. Adopting a theory first put forward by Professor Hutton—to whom I acknowledge my indebtedness—I have attempted to show how this could have been brought about by natural causes. By going much further back in time—and that is the charm of the evolution theory, that it imposes practically no limits as to time and space—I have supposed that in very ancient times two or more species of brevipennate birds, themselves the descendants of volant birds of a still earlier epoch, roamed over a great southern continent, which, by some convulsion of nature, was afterwards submerged, leaving its higher levels and mountain-tops exposed in the form of numerous scattered islands, on which the survivors of the wingless race of birds would naturally remain; that this state of things continued long enough—how long it is impossible even to conjecture—for the inhabitants of each island to develop new characters suited to their special environment in each case, thus bringing into existence in the end the various species of Dinornis and its allies as we now know them; that a widespread upheaval or elevation of the land followed, reuniting most of the islands, and resulting in the areas now known to us as the Islands of New Zealand, when, of course, the Struthious birds which had been developed in the smaller insular areas would be able, in process of time, to commingle on common ground. "In process of time," I say, because it would naturally take a considerable time for the newly-elevated areas to become covered with vegetation, although, on the other hand, it is quite possible that this elevation may have been gradual in its operation everywhere. I suggested that when, by the gradual subsidence of their domain beneath the waters of the great Pacific, they were driven as it were into a corner and overcrowded, the struggle for existence became a severe one, and the extinction of the race then commenced; that the more unwieldy giants, thus cabined and confined, were the first to succumb; and that the smaller species, perhaps in course of time differentiated from their ancestors by the altered physical conditions of their environment, continued to live on till their final extirpation by man within recent historic times. Professor Hutton supposes two successive submergences and elevations of the land at long intervals, but in this I am unable to follow him. Without that, the theory is sufficient, I think, to account for the co-existence in comparatively recent times of the various genera and species. But, as the modifications in form and page 87 structure constitute important generic distinctions, very long periods of time must have elapsed after the continental submergence before the final elevation of the land which made it possible for these wingless birds to commingle as they evidently did in later times. On the assumption that the North and South Islands were never reunited after the great submergence, these two areas having been independently formed by the fusion of different sets of islands, north and south, when the elevation took place, this theory will account for the singular fact that the Dinornis remains found in the North Island represent different species of birds from those of which remains have been so abundantly discovered in the South.

Professor Hutton is of opinion that the smaller forms of Ratitæ in New Zealand must have preceded the larger; and the fact that bones of only the smaller species of Dinornis and Syornis have as yet been found in both Islands seems to favour that view. But the evidence on this point is, I think, far from being exhausted, for fresh discoveries of Moa-bones are still being made from time to time, and in the most unlikely localities. On the other hand, whatever date may be assigned for the extinction of the Moa (and upon this question there is much difference of opinion), there seems little doubt that the colossal forms, such as Dinornis maximus, D. altus, D. validus, and D. excelsus, were the first to become extinct, because none of their remains have ever yet been found in the ancient kitchen-middens, mixed up with the rejectamenta of human feasts, or bearing evidence by chipping or gnawing of manipulation by man in a recent state; besides which they have sometimes been found in a highly fossilized or mineralized condition, unlike the bones of the smaller species, which contain much organic matter and often look perfectly fresh. I am of opinion that the larger forms are the more ancient, and are those that roamed originally over the afterwards submerged continent, and that the smaller-sized Moas, of different genera and species, are the descendants of those which had been specialised in the various islands during the long epoch following the continental submergence. Professor Hutton, accepting the outcome of Professor Parker's important researches into the embryology of this form, admits that in the Kiwi the hind limbs undergo a relative diminution in size between the time of hatching and the attainment of fully adult proportions, especially in the case of the female; and he adds, "This implies that the ancestral Kiwis were, like Megalapteryx, larger than the living birds; and we may infer the same thing from the great size of the egg. It is a legacy from a larger bird which is not easy to get rid of. The greater proportionate size of the female is probably due to its having to lay such a very large egg. The males have decreased in page 88 size more rapidly than the females, who were handicapped by such large eggs." Professor Hutton suggests that the reverse of this obtained in the case of the Moas; but there is no evidence of that. After a critical examination of all the evidence afforded by the bones and their distribution, he says, "Evidently Anomalopteryx and Palapteryx are the oldest forms; but if Palapteryx had wings it could not have been derived from the wingless Anomalopteryx; and, if the birds were increasing in size, Anomalopteryx could not have been derived from Palapteryx."^* Exactly so; but on my hypothesis these difficulties disappear, and the supposed conditions are in harmony with it. In this connection I may mention the curious fact that, although Anomalopteryx didiformis is one of the smallest of the Moas, scarcely exceeding in size the common Bustard, it had proportionately the largest skull of all the Dinornithidæ. Commenting on this, Professor Owen remarks that, if the peculiarly nutritious roots of the common fern contributed, together with buds or foliage of trees, to the food of the various species of Moa, the concomitant gain of power in the locomotive and fossorial limbs does not appear to have called for a proportionate growth or development of brain or of bill.

As with the Kiwi, it would seem that the development of the Moa was downwards, or in the way of degeneration, and the restriction of its range to small insular areas would doubtless favour this dwarfing process.

One can understand how in process of time the various species of Kiwi now known to us have become evolved from the parent stock by means of natural selection and the survival of the fittest, operating under well-established natural laws. Any divergences of character, however small to begin with, long continued and persisted in, would account for any number of so-called species in various parts of the country. For, a species—what is it? What does the name denote? Of what use is it to science except as an artificial definition, and for the greater convenience of systematic classification?

But the great difficulty in any theory on the subject is to account for the presence of the Grey Kiwi on the west coast of both Islands. Our knowledge of its existence in the North Island rests on a skin brought to me in a fresh state by Mr. Morgan Carkeek, who obtained it just below the snow-line on the highest of the Tararua Ranges, where, he states, he could have collected many more. For the present, I confess that the presence of this species in the North Island is very perplexing. One solution that suggests itself to my mind is that it may

^* "On the Moas of New Zealand," by Captain F. W. Hutton, F.R.S, Trans. N.Z. Inst., vol. xxiv., p. 149.

page 89 have been introduced in former times through human agency. It will be remembered that the Maoris have a tradition that the Pukeko, or Swamp-hen (Porphyrio melanonotus)—which, until recent years, when its haunts were invaded and drained, was excessively abundant in both Islands—was first introduced by their ancestors, who brought tame birds with them in their canoes from Hawaiki. It must be borne in mind also that the range of the Grey Kiwi includes the north-west coast of the Nelson District, for specimens which I obtained from that locality have been referred by Mr. Rothschild to his Apteryx occidentalis; and, furthermore, that the passage to and from the Kapiti coast, on the opposite side of Cook Strait, could easily be effected by the Maoris in their war-canoes. To entrap a few Kiwis, and bring them across alive in flax cages, would have been a very simple operation, and a far less ambitious project than that of stocking New Zealand with the Swamp-hen from far-off Hawaiki. The suggestion does not seem an unlikely one, when we remember that the Kiwi was always highly prized by the Maoris from the earliest times, both as an article of food and on account of its feathers.

On the theory put forward, and assuming, as we fairly may do, that the North and South Islands have never been united since the continental submergence,—in other words, that there was a simultaneous elevation of the two areas, north and south, with a permanent sea-channel dividing them,—we can understand and account for the existence of closely-allied representative species in the two Islands. I will give some examples: In the North Island the Blue-wattled Crow (Glaucopis wilsoni), in the South the Yellow-wattled Crow (Glaucopis cinerea); in the North Island the Saddleback (Creadion carunculatus), and in the South its grey ally, Creadion cinereus. It is true that Creadion carunculatus is found also in the South Island, which is the proper home of Creadion cinereus. This may, I think, be accounted for by an accidental colonization at some time, through the crossing of stray individuals to the other side of the Straits: even a single pair would suffice. Rare as this bird now is along the wooded shore on the north side of Cook Strait, I can remember that about thirty-five years ago it was more abundant there than in any other part of the country. But to resume my list of examples: In the North Island we have the Thick-billed Thrush (Turnagra hectori), in the South the common Turnagra crassirostris; in the North Island the Wood-robin (Miro longipes), in the South its congener Miro australis; in the North Island the Whitehead (Glitonyx albicapilla), in the South the Yellowhead (Clitonyx ochrocephala); in the North Island the White-breasted Tomtit (Myiomoira toitoi), in the South the Yellow-breasted Tomtit (Myiomoira macro- page 90 cephala); in the North Island the Pied Fantail (Rhipidura flabellifera), in the South the Black Fantail (Rhipidura fuliginosa). The same remark applies to the former of these as to the Saddleback, and the same explanatiom may be offered. It will, perhaps, be objected that this bird is too weak-winged to cross the Straits under any circumstances; but, as against this, I may mention that during the past twenty years there have been several well-authenticated cases (as recorded in my "Birds of New Zealand") of the Black Fantail crossing the Straits to the North Island; and of late years there has not been wanting evidence of its breeding here. What, therefore, is there to prevent such a species becoming naturalized in the North Island, and that without the intervention of any but natural causes? A gale of wind, under favourable conditions for the passage of the Straits, would alone be sufficient to occasion this dispersal of the species.

Now, all the representative forms I have named are accepted by ornithologists in general as good and true species. But take any two of them and compare them carefully. Who can for a moment doubt their common parentage?—how far back in time, it is not our present purpose to inquire. "Species," "subspecies," and "varieties" are now terms in general use among ornithologists, as well as among other specialists, and, as it seems to me, simply for the purpose of indicating the distinctness or otherwise of the lines of demarcation separating one from another in their present stages of development under the slow and invisible, but nevertheless inevitable and sure, processes of that law of evolution which governs the whole animal kingdom. When we come to study the matter more closely it often seems well-nigh impossible to draw-any specific line at all. So-called species often appear to run into one another by insensible gradations; so much so, indeed, that no two naturalists are agreed as to how much persistent difference is necessary to constitute a species, as distinguished from a sub-species or variety. Take, by way of illustration, the various forms of Woodhen (Ocydromus) inhabiting New Zealand. Dr. Bowdler Sharpe, who, as a rule, does not err on the side of "lumping," has recently declared (Bulletin, 1893, p. xxx.), that he finds it impossible to distinguish Ocydromus greyi of the North Island from Ocydromus earli of the South Island. This difficulty arose, no doubt, from the circumstance of his examination of the two forms having been confined to dried specimens. If he had been permitted to study the live birds he would have seen that, apart from the unmistakable difference in the general hue of the plumage, Ocydromus greyi has brown irides and legs, whereas the southern form (Ocydromus earli) has these soft parts of a lake-red colour. He says further (loc. cit., p. xxix.) that he page 91 prefers the simple arrangement in my first edition of "The Birds of New Zealand," limiting the number of species to three, to that of my second edition, fifteen years later, which admits five species of the group. This alteration, however, was not made by me hastily or without full consideration. I believe I have critically examined a very much larger number of Ocydromi than any other working ornithologist, and, although I do not wish to underrate the perplexities presented by the intergrading of plumage, I think I have adopted a very cautious rule of admission. Professor Hutton has recognised at least two more—namely, Ocydromus hectori and O. finschi—and a naturalist given to what is termed "splitting" might easily have increased the number still further. But this is the crux of the whole thing. In this particular instance the species of one naturalist is the subspecies of another, and the "local variety" of a third. What is this but the existence of transitional forms under the steady march of evolution?

But the question of the great variability of the South Island Woodhens opens up a larger one, which I confess myself quite unable to answer. How is it that in the North Island there is but one well-marked species of Wood-hen spread over its entire area, whilst in the South Island, under practically the same conditions of environment, there are at least four species, and possibly more, running into one another in such a way as to puzzle even the most expert ornithologists?

The Woodhen genus offers an exceptionally good example for a study of this sort, because, although furnished with ample wings, the quills are soft and useless, and the birds in consequence are flightless.

To take another instance of the kind: the Kakapo or Ground-parrot (Stringops habroptilus) has ample wings, and yet it is incapable of flight. The presence of this flightless bird, essentially the same in all respects, in both Islands, presents a difficulty which cannot be ignored. But, then, some species are more persistent in their character than others; and it may be that the Kakapo, as it existed in different areas before the final elevation, had reached its full development, and has remained stationary ever since. Its markings had become so exactly like the green mosses and other vegetation among which it feeds, thus effectually protecting it from birds of prey, and, in the absence of feral animals, the faculty of flight had become so unnecessary to it, that it is difficult to see in what direction natural selection could operate further to the advantage of the bird. It may be asked why, seeing that the Kakapo is flightless from long disuse of its wings, these members have not been more completely aborted, page 92 or dwarfed to mere rudiments, as in the case of the Kiwi? The obvious answer is that, allowing the necessary time,—in how many generations it is impossible to say,—the same results would naturally come about. How long it may have taken for the Kiwi to become practically wingless since the process of degeneration commenced we have no means of even guessing. But our pestilent civilization has, of course, put a stop to all that, and within measurable time the Kakapo will disappear altogether,—passing out of existence, in full possession of its wings, but feeble in their quills, and crippled by the atrophy of their muscular mechanism.^*

This incidental reference to the Kakapo and its protective colouring leads me into another very interesting field of observation—namely, the gradual adaptation, by natural selection of course, of certain species to their habitual environment by the acquisition of protective colours. The olive-green Bell-bird is almost invisible to the eye as it clings to the leafy climbing tawhiwhi (Metrosideros scandens), and inserts its brush-tongue into the corolla of the crimson flower; the grey-and-white Ground-pipit eludes the most practised eye as it perches on a dry log, or nestles by the wayside; the Bronze-winged Cuckoo so harmonizes with its surroundings as it rests silently on a low bough that you may be within a yard of it without detecting its presence; the Dottrel and the Godwit squat on the sands without being seen; the Wry-billed Plover hides itself among the loose pebbles and shingles of its own grey colour; the green Parrakeets are undistinguishable from the bright evergreen vegetation among which they feed; the Kaka, but for its discordant cry, would generally be safe from observation in the midst of the brown branches among which it loves to climb and explore for insects; the Rifleman, the smallest of our native birds, is quite invisible as it clings to the lichen-covered bark; and the Bush-wren hops in safety among the moss and vegetation of the forest to which its own colours so closely assimilate. And so one might goon selecting examples almost without end, in illustration of the well-known law to which I have referred as being almost universal in its application and effects.

Leaving birds, however, for one moment, let us consider the remarkable correlation of colour with its surroundings in

^* I think there is a manifest advantage in questions of this kind being investigated and discussed by ourselves on the spot. In illustration of this I may refer to a very curious mistake made by Mr. Alfred Russel Wallace, the great apostle of the creed of natural selection,—to whop, indeed, we all metaphorically doff our hats in respectful admiration. In writing of the New Zealand avifauna he confounds the Kakapo with the Kea, declaring that the moss-eating Stringops had become carnivorous, and is most destructive to the settlers' sheep!

page 93 the case of many of our lizards. The beautiful green lizard (Naultinus elegans) so exactly harmonizes with the manuka bushes on which it is usually found that it requires a very practised eye to distinguish it. The protective resemblance is rendered more complete by the leaf-shaped markings of yellow on the back and sides; and it is pretty clear that this particular character has been acquired by natural selection, or descent with modification for protective purposes, inasmuch as the young of this species is of a uniform green colour. These remarks apply with even stronger force to my Naultinus pulcherrimus, from Nelson, although, being a somewhat rare species, it is perhaps less noticeable. Here the irregular white markings, intermingled with the yellow and green, coupled with the animal's peculiar habit of curling up its tail in the form of a "Catherine's wheel," render the deception absolutely perfect. In this case also the young is of an almost uniform green colour, varied only with leaf-like markings of a darker green on the back. Then, again, as I have previously pointed out, the markings on the back of my Naultinus sylvestris (discovered by Mr. Annabell at Wanganui) so exactly resemble the minute yellow lichens which cover stems of dead wood in the forests as to render it at all times perfectly safe from detection in such situations. Naultinus sulphurous—whether we regard it as a distinct species or only a pronounced local variety—is admirably adapted by its uniform yellow colour to the sulphur deposits of Rotorua, where alone it has been met with. But to come to the common species: where could we find a more beautiful adaptation of colouring to the natural surroundings than in the case of our common tree-lizard (Naultinus pacificus), the shades and markings of which present an almost endless variety; or in that of the variable Mocoa ornata and Mocoa zealandica, inhabiting our stony places and roadside vegetation? A case even more remarkable still is that of our wonderful Sphenodon punctatum or Tuatara lizard. Now this lizard is so abnormal in its character that it forms by itself a distinct order of reptilia, and exhibits the most bird-like skeleton of all existing reptiles. It is perhaps generically the oldest inhabitant of the earth, being closely allied to the Prohatteria of the Permian period, its nearest relations being the various forms of Rhyncocephala which occur in the Trias. I have not time now to refer to the wonderful peculiarities of this living representative of a remotely ancient race; but I may mention that the Tuatara has been found to possess, concealed under the tough skin of the forehead, the vestiges of a third but now obsolete eye, the functional parts being present, even to the optic nerve! It has become extinct on the mainland; and it is a very curious fact that, through long isolation, it has become differentiated page 94 in colour in the several islands or groups of islets which it inhabits. With the exception of a green form, exhibiting some structural modifications, which I have dedicated to our great herpetologist, under the name of Sphenodon guentheri, it has been found impossible to distinguish these forms except as local varieties, sufficiently well marked however to admit of their being referred to their respective island habitats. What are these, I would ask, but incipient species? Allowing sufficient time under the existing conditions of life, and, reasoning by analogy, each island or group of islets must in the end possess a distinct species of Sphenodon exactly suited to its environment. It is, moreover, sufficiently clear that nothing but the island asylum could have saved this lowly-organized and archaic form from absolute extinction.^*

Less fortunate has been another form of New Zealand lizard, the Kawekaweau, whose quasi-arboreal habits of life have prevented its taking advantage of this last refuge. From the accounts of the natives, the Kawekaweau appears to have been a form of iguana inhabiting the deep forest, and there can be no doubt that it lingered in the land till within the last thirty years, when the remnant of its race succumbed to wild pigs and other natural enemies. It is always described by the Maoris as beautifully marked with alternate

^* I may here remark that one is surprised to find a naturalist like Mr. H. O. Forbes—fresh from New Zealand, and with all the literature on the subject at his command—in his recent address to the Royal Geographical Society, referring to the Tuatara as "a curious and ancient form of lizard now absolutely confined to an islet off the coast of the North Island." Here is a statement of fact, made with apparent scientific accuracy, and yet far wide of the truth. It is quite true that the tuatara has become extinct on the mainland, but it still exists in considerable numbers on the rocky islands adjacent to our coasts. It is common on the Hen and Chickens, on Cuvier Island, on the Poor Knights, on the Mercury Islands, and on the Barrier Islands, in the Hauraki Gulf. Coming further south, it is abundant on the Alderman Islands, on Motunau or Plate Island, on the Island of Karewa in the Bay of Plenty, on the Rurima Rocks, on Whale Island, and on East Cape Island. It inhabits the various groups of islands in Cook Straits, such as Stephen Island, the Brothers, and the Chetwynd Islands. It has been recorded from other localities; and it is highly probable that it exists on many unexplored islets or rocks lying off the coast of the North Island. The last recorded specimen from the mainland was captured in Evans Bay about the year 1842, and was preserved by Dr. Monteith, one of the early Wellington settlers. He presented it tome some twelve years later, and it is now in the collection of the Colonial Museum. The extermination of this lizard is attributed to its natural enemies of modern times, pigs and rats, whose ravages it has hitherto been able to escape on the small uninhabited islands. Unfortunately, of late years even there it has been exposed to the persecution of travelling natural-history collectors, one of whom is said to have forwarded at one time to Europe no less than three hundred specimens preserved in spirits.

page 95 bands of colour, and reaching at maturity to a length of 2ft. or more.^*

But, although these are good illustrations of the correlation of colour and of the extinction of well-established forms in the struggle for existence, I feel that I am rather digressing from the real subject of my address.

Closely connected with this subject of assimilative colouring is that of the gradual adaptation of structure to the conditions of existence. In my "Birds of New Zealand" I have called attention to some remarkable cases of this kind, and notably to that of the Huia (Heteralocha acutirostris)—an instance quite unique in the whole class of Birds—where the sexes present differently-formed bills, specially adapted to their habits of life and general economy. Now, on what principle apart from the Darwinian theory can we explain this remarkable sexual difference?

And to mention another case, that of the Wry-billed Plover (Anarhynchus frontalis) is a very remarkable one. In this instance the bird has the bill turned or twisted to the right, this asymmetry being admirably adapted to this plover's peculiar mode of feeding among the pebbles of the seashore. In the case of our beautiful Red-necked Avocet (Recurvirostra novæ-hollandiæ), the curvature of the bill is upwards instead of sideways; and in both forms this marvellous departure

^* It is significant that the Long-tailed Cuckoo (Eudynamys taitensis), whose streaming tail-feathers are handsomely barred in their whole length with chestnut and black, is also known by the name of Kawekaweau in many parts of the country. In like manner the name Kakariki (indicative of the colour) is applied alike to the green lizard and to the Green Parrakeet of our woods.

page 96 from the normal type of a plover's bill is congenital, being present in the unhatched embryo. Then, again, what is the Rock Wren (Xenicus gilviventris) but an extreme development of the Bush Wren (Xenicus longipes)—which has put off its green plumage for the dun-coloured dress more in harmony with its surroundings among the rocks on the open mountain, and has acquired a longer hind claw, so as to fit it for this different habitat—or vice versâ? The particular direction of the development does not of course affect the argument. And it is a significant circumstance that I possess intermediate forms; so much so, in fact, that I have been in doubt as to which of the two species they really belonged. Or, to take just one more case: who can doubt that the fleshy membrane on the bill of our Blue Mountain Duck (Hymenolæmus malacorhynchus) has been specially developed to enable it to hunt the more successfully for the peculiar stone-encased caddis-worm of our mountain streams, which now forms its principal article of food?

But now, to revert to my main line of argument: In considering the problem of representative species in the North and South Islands respectively, it must be borne in mind that there are probably many broken links in the chain of succession through the disappearance of representative forms. We all know that the existing avifauna is being stamped out and destroyed by a variety of artificial causes, not the least among them being the naturalization of foreign birds by way of acclimatization, on the one hand, and the introduction of bloodthirsty animals like stoats, weasels, and ferrets, on the other. But long before the effects of our drastic colonization made themselves felt, many of the ground species were dying out, in obedience, no doubt, to that inscrutable law of nature whereby races of animals and plants, apparently of their own accord, die out and give place to other forms of life. I remember, when I was a boy, the interest with which I followed the Maoris' descriptions of birds that had even then become rare or were disappearing from the land. One bird, a species of Rail apparently, was often mentioned to me under the name of Pukunui—so called from the abnormal size of its stomach. It was described as a reddish bird, frequenting swamps and marshes, and I was constantly hearing of it. Indeed, I never made an excursion among the Maoris anywhere without making diligent inquiry for the Pukunui, so much so that the older men thought I had Pukunui on the brain. I offered liberal rewards, and often felt that the bird was almost within my grasp. At length, at the small bush settlement of Mareikura, on the North Wairoa River, one was caught at the edge of a raupo swamp near the village by my trusty lieutenant, Tamati Nui. It had been taken unhurt, page 97 and, pending an opportunity of forwarding it to me, it was kept tethered by a flax-string in the marae or open courtyard. A passing Maori unconsciously snapped the string with his foot, and, unfortunately for me and for science, this "rara avis in terris" made its escape. More than forty years have elapsed since this occurrence, and I have never so much as heard of the capture of another Pukunui!

In this connection, and also as marking the tendency towards extinction in certain lines, it is of interest to notice that the Ralline genus Notornis was contemporary with the smaller species of Moa, and that the bones of the living bird obtained in Otago differ so much from those of the fossil remains discovered by Mr. Walter Mantell at Waingongoro, in the North Island, and referrred by Professor Owen to a form which he named Notornis mantelli, in honour of the discoverer, that Dr. A. B. Meyer, of Dresden, proposes to discriminate two species, distinguishing the southern form as Notornis hochstetteri, in compliment to the Austrian explorer. Assuming Dr. Meyer to be right in his determination, we have here a beautiful instance of representation, the North Island species having long since disappeared, whilst the South Island species is verging on extinction.

I think I have now noticed all the main points bearing on this question arising out of a study of the birds of the North and South Islands. But it is to the smaller insular areas that we naturally look for the strongest proofs in support of our theory, because the conditions there are altogether more favourable. Let us first take the Chatham Islands, lying about four hundred miles to the south-east of Wellington. It is very clear that there has been no land communication between the Chathams and New Zealand since the continental submergence. This has allowed time for the production by natural selection and the survival of the fittest of several distinct species. Now, let us see what we have. Notably, a new species of Bell-bird (Anthornis melanocephala) has come into existence—a much larger and finer species than our Korimako (Anthornis melanura), although presenting the same adolescent and sexual phases of plumage. But the curious thing about it is that, side by side with this endemic species, our Bell-bird is also to be found in the Chatham Islands and on the adjacent islets (Pitt Island and Mangare). To my mind the only explanation of this is the same that I have given in a former paper (Trans. N.Z. Inst., vol. xxiv., p. 65) for the occurrence side by side of Platycercus unicolor and platycercus erythrotis on Antipodes Island—namely, that the smaller species owes its existence there to a comparatively-recent colonization, the result of some accidental flight or migration from the mainland,—with this difference: that in page 98 the case of Platycercus erythrolis the irruption of the parent form must have been long anterior to the colonization, so to speak, of the Chatham Islands by the New Zealand Bell-bird, inasmuch as there has been time for a sufficient modification of characters to entitle it (in the opinion of many ornithologists) to take specific rank, distinct from Platycercus novazealandiæ. As to such occasional migrations there would be nothing in the distance, at any rate, to negative such a supposition. Then, again, we have a Wood-pigeon (Carpophage chathamiensis) very similar to the New Zealand bird, but sufficiently differentiated to be accepted as a good species. Other representative forms are the Black Robin (Miro traversi), the Bush Warbler (Gerygone albofrontata), and the Chatham Island Fern-bird (Sphenæacus rufescens). The near relatives of all these are to be found in New Zealand. But, instead of Ocydromus, there is a small flightless rail—a degenerate Oeydromine form—which Professor Hutton has made the type of a new genus, Cabalus modestus. To this genus (although the form is less aberrant from the typical Rallus) I have referred Dieffenbach's Rail, which is now extinct, the only known example being the one in the British Museum, obtained about the year 1845.

So far as we are aware no bones of Dinornis have yet been discovered in the Chatham Islands, but I have no doubt that they will be sooner or later; and I feel pretty sure that when discovered they will be found to be of different species (perhaps of different genera) from those known to have inhabited New Zealand in comparatively recent times: that is to say, our theory seems to require, for the sake of consistency, that this should be so, inasmuch as the same differentiation would be taking place in the Chatham Islands as in the other insular areas after the great submergence. And, as the Chatham Islands unquestionably formed part of that ancient continental area of which I have been speaking, we may reasonably expect to find there, sooner or later, fossil remain; of the earlier forms (such as Palapteryx), similar to those that have been unearthed in the North and South Islands of New Zealand. As to the remarkable avian remains recently discovered by Mr. H. O. Forbes in the Chatham Islands, and referred by him to a genus allied to Archæopteryx, we may feel equally assured that similar remains exist in New Zealand, and will hereafter be found in abundance to reward the diligent explorer.

The Auckland Islands, again, offer several good examples. Among the species specially developed there may be mentioned a Ground-pipit (Anthus aucklandicus), very readily distinguishable from our New Zealand bird by its rather larger size and warmer colouring; and a Green Parrakeet (Platycercus auck- page 99 landicus), much smaller, but in other respects similar to our Platycercus novæ-zealandiæ. Representing our Rallus philippensis, there is a very distinct species of Rail (Rallus muelleri, Rothschild), of which the only known specimen is in the Natural History Museum at Stuttgart; and, as if representing our Anas chlorotis, there is a flightless Duck (Nesonetta aucklandica) frequenting the seashore as well as the streams. But, what is still more significant and curious, there exists in the Auckland Islands a species of Merganser (Mergus australis), of which there is no representative in New Zealand, or indeed anywhere else in the Southern Hemisphere. The Bell-bird is there also, but it seems to be absolutely identical with the New Zealand form (Anthornis melanura), showing, as I think, a comparatively recent introduction.

On Antipodes Island, as already indicated, there is a strictly endemic Parrakeet (Platycercus unicolor), a species living abundantly on this oceanic rock, but not to be met with in any other part of the world, and commingling with a species (Platycercus erythrotis) more nearly approaching to the typical Platycercus novæ-zealandiæ. Going further south we come to Macquarie Island, where there is a Rail differing so perceptibly from ordinary examples of Rallus philippensis that Professor Hutton has proposed to distinguish it as Rallus macquariensis; and, although I am not prepared to concede to it distinct rank as a species, its presence there is another proof of the existence of transitional forms. It is an inexplicable fact, however, that on the same island is to be found the flightless Ocydromus earli, differing in no respect from examples obtained in New Zealand and on Stewart Island.^*

On the Snares, a group of islets about seventy miles south of the southernmost extremity of New Zealand, there is a peculiar form of Fern-bird, which I have recently distinguished under the name of Sphenæacus caudatus, very similar to Sphenæacus punctatus of New Zealand, but quite distinct as a species, and being intermediate in character between the last-named bird and Sphenæacus rufescens of the Chatham Islands. Now, no ornithologist who has studied the subject can doubt that these three closely-allied forms, although now perfectly distinct as species, have sprung from a common parent-form. Curiously enough, another Chatham Island bird, the Black Robin (Miro traversi) is abundant on the Snares, although not found in any part of New Zealand.

Then, again, the Kermadec Islands possess a Green Parakeet which Mr. Rothschild declares to be distinct; and although many naturalists will insist that this and the other island forms are, for the most part, local varieties of the well-known Platycercus novæ-zealandiæ, their very existence as such is the best evidence of the constant operation of the law of development by variation and the survival of the fittest.

Even the sea-birds, whose range is practically unrestricted, furnish additional and, indeed, very important evidence. Mr. Rothschild, with the aid of Mr. Salvin, our great authority on the Petrel family, has lately been investigating the Albatroses of the Southern Hemisphere. Talking over the result with me, he said, "Why, every group of islands seems to have its own species of Albatros!" And, in a sense, this is true. Here we have birds enjoying the freedom of the wide ocean-commingling daily on their great hunting-fields on the face of the deep; and then, on the approach of the reproductive season, separating themselves, according to their species, and repairing to their own island-nurseries to breed. As far as our information at present goes, Campbell Island is held exclusively by my Diomedea regia, the noblest member of the group. The Auckland Islands are occupied by thousands of Diomedea exulans, with the exception of a small colony of the former breeding in a remote corner of the main island, and at a somewhat earlier season—according to Captain Fairchild's observations, four or five weeks earlier. On the Snares Diomedea salvini (hitherto known here as Diomedea cauta) reigns supreme. The Albatros breeding on the Sisters, some outlying islands in the Chatham group, on which the Maoris are said to have collected as many as a thousand young birds in one season, is probably Diomedea melanophrys, which is plentiful in that latitude; but I have not yet been able to obtain any specimens from that locality for identification. The breeding-place of Diomedea bulleri, Rothschild (hitherto confounded with Diomedea culminata), I have not yet discovered, all the specimens of that form known to us (some twenty in number) having been captured off the Otago coast.

Many of the smaller species of Petrel, it may be observed, confine themselves to particular islands: for example, Puffinus carneipes is the commonest of birds on the Island of Karewa, in the Bay of Plenty, but, so far as I am aware, has never been found breeding on any other island off our coast.

As with the Petrels, so in a limited sense with the Shags and Penguins, many of the species of both having their particular island group, which they resort to, for breeding purposes, to the exclusion of all others.

Finally I may refer to the Snipes, the local distribution of which is very remarkable indeed. My Gallinago pusilla, page 101 the smallest of the Snipes, is an inhabitant of the Chatham Islands, where it is apparently very plentiful, Mr. Rothschild having, as he informs me, received from his collector, in one lot, fifty-four specimens. Sir James Hector has recorded two specimens from New Zealand, but it is evidently only a straggler with us. Gallinago aucklandica appears to be confined to the Auckland Islands, Gallinago tristrami to Antipodes Island, and Gallinago huegeli to the Snares. It will be seen therefore that these island-species are very sedentary; and they have no doubt acquired their distinctive characters through long isolation. Whether they are accepted by all ornithologists as true species or only as local varieties does not affect in the slightest degree the force of our argument in favour of the creation of new forms by a process of descent with modification. But I have probably pursued this branch of the subject quite far enough. There is another aspect of the question upon which I should like to say a few words before I close.

I have always stated my belief that our colossal forms of Dinornis were the most ancient and were the first to become extinct. Those on which the Moa-hunters feasted (as attested by the remains now found in the old kitchen-middens) were confessedly of a smaller stature. Probably the very last to disappear was the small Mesopteryx didinus. In 1878 Mr. Squires, of Queenstown, obtained and sent to the British Museum the head, with a continuous part of the neck, of this species of Moa, with the trachea enclosed and covered by the dried integument, and exhibiting even the sclerotic bone-ring of the dried eye-balls; also the bones of both legs with the feet covered by the dried skin, with some feathers adhering to it, and with the claws intact. Be that as it may, the only representatives of this Struthious race we have at the present day are the diminutive Kiwis, of which I have been treating. This remarkable sequence in the development of animal life on the earth, the larger forms preceding in geological time the smaller, appears to have been universal. The distinguishing feature of the Mesozoic period was the development of Saurians of marvellous size. From the Oolitic beds in the Rocky Mountains of North America the remains of huge Dinosaurians have been obtained, among these being the Atlantosaurus, the largest land animal yet known to have existed on the earth; for Professor Marsh describes it as "having been between 50ft. and 60ft. long, and, when standing erect, at least 30ft. high!" At the present day our largest saurians are crocodiles and alligators. But, coming down to Pliocene and Pleistocene times, we have only to think of the mammoth and the mastodon, the dinotherium and the megatherium, the diprotodon and the Irish elk, and compare them with the page 102 elephant and the hippopotamus, the rhinoceros and the buffalo, of the present epoch, to realise the full force of this truth. But these revolutions in the animal world have, in both the Northern and the Southern Hemisphere, been accompanied by corresponding alterations on the earth's surface and by climatic changes of a very extensive kind. To give one illustration: The mammoth was an animal which subsisted on herbage and vegetation of all kinds; and, looking [unclear: t] its unchecked and ever-increasing numbers, it would clearly have required a growth of tropical luxuriance to satisfy the wants of its capacious stomach. But where do we now find the remains of these ancient herbivora? Not buried in tropical regions, but frozen and embalmed amid the eternal snows of Siberia, where they have been preserved intact fa thousands of years. What a revolutionary change of climate do these facts imply! And how sudden must have been the translation from ultra-tropical verdure to the utter desolation of Arctic frigidity when the entombment and refrigeratio[unclear: n] these herb-eating leviathans took place fresh from their feeding-grounds!

But now let me give another illustration nearer home—one drawn from the recent discoveries of Dr. Stirling, F.R.S., in South Australia, the importance of which, from a [unclear: scienti] point of view, it would be impossible to overestimate. I will shortly state the facts so far as they have yet become known In the central part of South Australia there is a vast stony desert lying to the eastward of Lake Frome and to the westward of the Grey Range. It is described as being unspeakably arid and desolate, abounding in salt-pans, of which Lake Mulligan is the largest. This forbidding district is entirely destitute of fresh water and almost absolutely devoi[unclear: d] animal life of any kind. The intrepid explorer, Captain Sturt, in 1844 penetrated about half-way across this inhospitable plain, and then, after suffering great hardships, ha[unclear: d] make his way out of it to escape absolute starvation. Up to the present time this region has been to all intents and purposes a sealed book. But a few months ago an important discovery of fossil bones was made at Lake Mulligan, and, chiefly through the scientific enterprise of Dr. Stirling (aided all through by the generous liberality of Sir Thomas Elder), this discovery has been followed up with very astonishing results A correspondent of the Scotsman, writing on the spot and from his own knowledge and observations, states that, after four months' digging among the gravels of the valley of the Mulligan, some two thousand bones, representing seventy different mammals and birds hitherto unknown, have been unearthed and safely lodged in the South Australian Museum at Adelaide This collection comprises the first complete skeleton of Dipro- page 103 todon australis, a gigantic marsupial considerably exceeding the rhinoceros in size, the remains of a giant wombat as large as a half-grown bullock, several kinds of colossal birds equalling in stature the Moa of New Zealand, and several species of gigantic kangaroos! The writer's reflection is as follows: "What a different picture of the past history of this country is brought to light by these discoveries! On the sides of these mountains lying between Lake Frome and Lake Torrens must have grown huge trees, and all around there must have been a dense tropical growth, exceeding in luxuriance the forests of the eastern slopes of the Andes in South America!"

Commenting on this remarkable sequence of animal life on the earth at different periods of its history in the same geographical areas, Sir John Lubbock observes, "Our prehistoric ancestors hunted the mammoth, the woolly-haired rhinoceros, and the Irish elk; the ancient Britons had the wild ox, the deer, and the wolf. We have still the pheasant, the partridge, the fox, and the hare; but even these are becoming scarcer, and must be preserved first in order that they may be killed afterwards."

I fear I have already trespassed too long on your kind indulgence, but the subject is a very seductive one, and, in treating of it, however briefly, it is difficult to keep within the ordinary limits of an address. But just one word in conclusion. As you will have gathered from the views I have had the privilege of placing before you this evening, I am a thorough disciple of Darwinism in the higher sense of that term. I do not think it is possible to explain on any other hypothesis the wonderful variety and complexity of living forms that inhabit this beautiful world of ours. We must, as it seems to me, acknowledge with the author of "The Origin of Species," in one of his later works, that "man, with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his godlike intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers, man still bears in his bodily frame the indelible stamp of his lowly origin." I do not accept, however, as many do, the purely materialistic theory, because I am a believer in the truths of revelation and in the spiritual destiny of man. As that of a humble worker in the field of science, earnestly seeking the truth, this is, so to speak, my confession of faith as a naturalist. To adopt Mr. Wallace's admirable language on this point, I am "thus relieved from the crushing mental burder: imposed upon those who—maintaining that we, in common with the rest of nature, are but products of the blind page 104 eternal forces of the universe, and believing also that the time must come when the sun will lose his heat, and all life on the earth necessarily cease—have to contemplate a not very distant future in which all this glorious earth—which for untold millions of years has been slowly developing forms of life and beauty, to culminate at last in man—shall be as if it had never existed; who are compelled to suppose that all the slow growths of our race struggling towards a higher life, all the agony of martyrs, all the groans of victims, all the evil and misery and undeserved suffering of the ages, all the struggles for freedom, all the efforts towards justice, all the aspirations for virtue and the well-being of humanity, shall absolutely vanish, and, 'like the baseless fabric of a vision, leave not a wrack behind.' As contrasted with this hopeless and soul-deadening belief, we, who accept the existence of a spiritual world, can look upon the universe as a grand consistent whole, adapted in all its parts to the development of spiritual beings, capable of indefinite life and perfectibility. . . . We thus feel that the Darwinian theory, even when carried out to its extreme logical conclusion, not only does not oppose but lends a decided support to a belief in the spiritual nature of man. It shows how man's body may have been developed from that of a lower animal form under the law of natural selection; but it also teaches us that we possess intellectual and moral faculties which could not have been so developed, but must have had another origin; and for this origin we can only find an adequate cause in the unseen universe of Spirit."