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Show 510 ISLAND LIFill. [rAnT n. New Zealu.nd is shown to be so completely contine~tal in its geological structure, and its numerous wingless burls Ro clearly imply a former connection with some .other land (a.s. do its numerous lizards and its remarkable reptile, t~e Hattena), t] t the total absence of indigenous land-mammaha was hardly 1a · h · to be expected. Some attention is therefore giVen to t e cunous animal which has been seen but never captured, and. this is shown to be probably identical with an animal referred to by Captain Cook. The more accurate knowledge which has recently been obtained of the sea bottom aro~nd New Z~alancl enables us to determine that the former connectiOn of that Island with Australia was towards the north, and this is found to agree well with many of the peculiarities of its fauna. The flora of New Zealand and that of Australia are now both so well known, and they present so many peculiarities, ancl relations of so anomalous a character, as to present in Sir Joseph Hooker's opinion an almost insoluble problem. Much additiona.l information on the physical and geological history of these two countries ha~, however, been obtained since the appearance of Sir Joseph Hooker's works, and I therefore determined to apply to them the same method of discussion and treatment which has been usually successful with similar problems in the case of animals. The fact above noted, that New Zealand was connected with Australia in its northern, tropical portion only, of itself affords a clue to one portion of the specialities of the New Zealand flora-the presence of an unusual number of tropica.l families and genera, while the tempera,te forms consist mainly of species either identical with those found in Australia or closely allied to them. But a still more importa.nt clue is obtained m the geological structure of Australia itself, which is shown to have been for long periods eli vided into an eastern and a western island, in the latter of which the highly peculiar flora of temperate Australia was developed. This is found to explain with great exactness the remarkable absence from New Zealand of all the most abundant and characteristic Australian genera, both of plants and of animals, since these existed at t~at time o~ly in the western island, while New Zealand was 1n connectwn with the eastei·n is~and alone and with the tropical portion of f'I!AP, XXIV.) SUMMARY AND CONCLUSION. 511 ---- -- it. From ~hese geological and physical facts, and the known powers o~ dispersal of plants, all the main features, and. many of the detmled peculiarities of the New Zealand flora are shown necessarily to result. . Our l~st cha~ter is devoted to a ·wider, and if possible more mterestmg subJect-the origin of the European element in the floras .of New Zealand and Australia, and also in those of South Ame~ICa and ~outh Africa. This is so especially a bota,nical ~uestwn, that It was with some diffidence I entered upon it, yet It arose so naturally from the study of the New Zealand and Australian floras, and seemed to have so much liO'ht throw upon it by our preliminary studies as to chanaes of ~limate an~ the causes which have favoured the distribution of plants, that I felt my work would be incomplete without a consideration of it. The subject will be so fresh in the reader's mind that a complete summary of it is unnecessary. I venture to think ho~ever, that I have shown, not only the several routes b; whiCh the northern plants have reached the various southern lands, but h~ve pointed out the special aids to their migration, and the motive power which has urged them on. . I~ thi~ discussion, if no where else, will be found a complete JUStificatiOn of that lengthy investigation of the exact nature of past changes of climate, which to some readers may have se~med unnecessary and unsuited to such a work as the present. ~Itho~t the clear and definite conclusions arrived at by that discusswn, and those equally important views as to the permanence of the great features of the earth's surface, and the wonderful dispersive powers of plants which have been so frequently brought before us in our studies of insular floras I should not have ventured to attack the wide and difficul~ problem of the northern element in southern floras. In concluding a work dealing with subjects which have occupied my attention for many years, I trust that the reader who has followed me throughout will be imbued with the conviction that ever presses upon myself, of the complete interdependence of organic and inorganic nature. Not only does the marvellous structure of each organised being involve the whole past history |
