THE LOST CONTINENT.

New Zealand Herald, Volume XLIV, Issue 13625, 19 December 1907, Page 7

THE LOST CONTINENT.

I|UB-ANTARCTIC EVIDENCE. ■— ■—-....■■ SINKING OF THE LAND. ANIMAL LIFE ON AUCKLAND t ISLANDS. INTERESTING DEDUCTIONS. [BY PROFESSOR BENIUM, F.R.S.] Tut Auckland Islands arc a compact (jrtfap, lying nearly 270 miles due south of th© West Capo of New Zealand—that is, gontewhat to the west of south of the Bluff. The group is somewhat triangular in outline, between 25 and 30 miles from north to south, and its southern portion measures about 12 miles from east to west. Jt consists of a large island, the Auckland Island, with Adam Island running along the whole extent of its southern limit, the strait between them being Carnloy Harbour. At the north the main island is much narrower, and a circle of islands— Hoss Island. Enderby Island, Ewing Island, gad Ocean —en lose the spacious Jfoss Harbour. The west coast is formed l»y precipitous cliffs of volcanic rock rising vcrti dly upwards to a height of 800 ft or more; and this wall is unbroken along its entire extent. The east coast, however, although precipitous, is eaten into by several fi'w inlets, or amis, reminding one of tlie West Coast Sounds. The land is everywhere high, some of the hills rising to nearly 2000 ft. An excellent account of the geography of this group is given in the "Transactions of the New Zealand Institute" for 1869 by Mr. Raker, the chief surveyor of Southland at that time; while a more chatty account was given by Judge Chapman in the same periodical in 1890.

Isolated islands such as the Aucklands have had one of two modes of origin: they have cither been formed by some submarine Tolcauic eruption raising the ocean floor, above high-water mark, the molten volcanic mass belched forth from the deep parts of the crust of the earth ultimately cooling to form the rocks of which the islands now consist; or. secondly, such islands have been, at some earlier period of the earth's history, in land continuity with some continental area; and at a subsequent epoch the intervening land has become submerged, so that all trace of the bridge has disappeared. In order to decide whether the- Auckland Islands owe their origin to this or to that method recourse is bad —(a) The character of the rocks of which the land is composed; (b) to the relations of the animals and plants inhabiting the islands; and (c) also to the determination of the depth of the sea immediately surrounding the islands.

Of these three lines of evidence, the last is least known, for so far as I am aware no systematic soundings have been taken between Hew Zealand and the Aucklands; but on our return trip Captain Bollons lowered the lead at three spots, in a line due north of the islands. At six miles a depth of 63 fathoms was obtained; at 13 miles, 85 fathoms; and at 20 miles the bottom was reached at 96 fathoms. This indicates that the islands do not rise from great depths, as do true volcanic islands, but that, like a continent, there is a gradually sloping shelf of land passing outwards towards deep water. If the Auckland Islands were formed by a submarine eruption we should expect that a much greater depth would have been found much nearer to land. Moreover, the few soundings that have been previously taken indicate that nowhere between the "islands and New Zealand is there a greater depth than 1000 fathoms, which is not exceeded even as far smith as the Macquarie Islands; and beyond that ire know nothing. The oceanographical evidence, then, leans slightly towards the conclusion that the Auckland Islands are part of a submerged continental area. The geological evidence is in the same direction, although ho sedimentary rocks were discovered, the fossils of which might be compared with those of New Zealand— as are, in fact, known in the case of tlie Campbell Islands; yet Mr. Speight found granite and gneiss in the Mnsgrave Peninsula, which are signs of a continental connection. Although, then, the first two lines of study do not enable us to arrive at a very definite conclusion, yet the study of the inhabitants, both animal and vegetable, yields pretty convincing evidence as to the mode of origin of the islands.

zoor.nr;ifia i, viuh.,\ik. In this article we are concerned with the I xoologieal evidence. We have long beet familiar with the birds,- of which art peculiarly interesting, such as the mergan ■ «r and the flightless duck; but I must refei only to those that have a bearing on the question under discussion. The Auckland / Island rail is nearly related to the Macmaarie Island rail and to the rail of New Zealand. The snipe is closely similar tc those of the Snares and the Chathams. II : is practically flightless, and has J*en almost, if not quite, wiped out of existence on the largest island, on which I saw none during this visit. Possibly the pigs have led to its extinction. Oil" Adam Island, however, I found them pretty numerous, and easily captured. The sundplover, als'j closely related to that of New Zealand, is getting rare; as is also the parrukeet. All these birds, as also the sparrowhawk, bellv bird, and tui, are evidence of a former ;.' land connection with New Zealand; the differences, when present, affect small.de- / tails of structure, which are only noticeable to the trained ornithologist, and it is' clear to an evolutionist that these birds are descended from those now existing in the "lain islands of New Zealand. Most "of them are feeble of flight— feeble to have reached their present home by flight across the 250 miles and. more that separate .this home from that of their ancestors; «id this of itself— from much other evidence—is sufficient to lead the zoologist to recognise in the Auckland Islands a Portion of an old continental land, of which New Zealand now forms the chief relic— » land that extended southwards at least f as far as the Macquaries; eastwards to include the Chathams ; and north-westwards to New Caledonia. But other groups of animals are, perhaps, ' even more convincing, animals which are not endowed even with the small powers of super-ocxanie and sujier-torrestrial locomo- • tion possessed by some of the birds. Beetles We Jong been known from the islands, &■ some having been obtained by the French I expedition in 1810, and others by Captain m Hutton a few years ago. In all a dozen species have been adequately described. They belong to nine genera, half of which We found in New Zealand, and one of the species is incapable of flight; not owing to its loss of wings while inhabiting the islands, for it belongs to a family in which the wing covers are always united so as to forbid flight. This bottle (Adelium) lives under logs, and it is difficult to suppose that it could be carried thither by any of the ordinary agents of dispersal. The tooths, of which Mr. Hudson captured many , Wpresentatives of 17 species, belonging to M genera, all living in New Zealand, are too feeble of flight to bo transported to the Aucklands, except on the supposition of ifavourable westerly winds. Most of the '' «ies belong to New Zealand genera, though , too species are distinct. The common kind- ■„■;', hopper is everywhere abundant under logs and stones, even on the tops of the mountains. [t ■ But slugs cannot fly nor jump, and <annot be conveyed by any means but by their own efforts of crawling, and two ; ,. *peciea ate very common, both belongi , l *% *** the typical New Zealand genus ~. Aworaeophorns, while some of the earthworms recently collected by me both durI ' .rSMhis recent trip and during my visit [■■ ■ "i February, include several belonging to \, ' i, i genera (Plagiiochaeta, Octoehaetus, Rhooodvilus) foutnd in New Zealand, and of, wl*V ! animals, earthworms are most in- | ' .tolerant of sea water.

THE CONNECTION i WITH SOUTH . AMERICA, _ All those zoological'fact's— to say nothing of botanical facts—point unmistakably to the origin of the Auckland Is,lands as a portion of a lost continental area, of which Now Zealand also formed a portion. But this is not all, for many of the animals and several of the plants are very closely related to those living in the sub-Antarctic, islands—Kergvelen, the Crosets, Falkland Islands, South Georgia, as well as to the southern portion of South America, viz., Fuegia, Chili, Patagonia. Thus, amongst insects, Mr. Hudson found a species of a moth, Drepanodes, which has a striking and almost unique habit of falling to the ground when disturbed, instead of flying away, and it does so with its wings field rigidly outspread, so that, with its dull, brownish colouration and peculiar markings, it presents every resemblance to a dead leaf. This moth genus occurs in New Zealand, but it is also a characteristic South American genus, and occurs nowhere else. It is impossible to suppose that such a moth could, at the present time, flv from the Auckland Islands to the nearest subAntarctic island—Kerguelen— for this is 90deg. of longitude distant. Moreover, other New Zealand moths (though not yet identified in Auckland Islands) are also related to South America, having very similar species in Chili. We can only suppose that in past times, not very long ago as the geologist counts time, there was more land around the Southern Pole, so that the distance across the ocean was materially reduced, in order to account for the ancestors of these moths passing between New Zealand and South America. Landplanarians — little flat, elegantly-coloured, slimy creatures, not unlike very much-flattened slugs—occur in abundance under fallen trees and logs in the Auckland Islands, as in New Zealand, and the leading European authority on the group. Dr. Von Graff, speaking of their distribution, points out that the group of Landplanarians is best developed in New Zealand. Australia, and South America. These little creatures, a couple of inches in length and less, have very little power of locomotion, and certainly cannot swim in the sea, or withstand contact with sea water, and it is unlikely that their eggs could bo carried in mud on birds' feet for any great distance, even if they ever became attached in this way to birds' feet. Consequently, it is argued., a great, continent must have formerly existed where now the Antarctic ice sheet lies, and that these various sub-Antarctic islands are the highest mountain tops of such submerged Antarctic continent, which thus put South America, Australia, New Zealand, and South Africa into land connection; not necessarily at the same time, however, but at different epochs, the different continental land mases were joined. At that period Patagonia was disconnected with the rest of South America, and possibly at no time was the Antarctic region covered simultaneously j by a continuous land tract, but land bridges rose and fell in the ocean, placI ing at one time New Zealand in connecj tion with Patagonia, at another time Australia and Africa. MEANS OF IMMIGRATION.

Similar evidence is afforded by several other groups of animals. Peripatus, which is not now common in New Zealand (but of which I could find no representative in the Auckland Islands), belongs to a genus found also in Australia, with one species in Chili, though the majority of the South American species belong to a distinct genus. Although the Auckland Island spiders have not yet been worked over, yet they are no doubt closely related to the New Zealand forms; and we know enough of this latter to justify Mr. Pocock, a leading British authority on the group, to • say of our trapdoor, spiders: V They furnish strong evidence in favour of a former union between the Australio-Zealandina continental areas and the southern extremity of South America." Ortce more we may appeal to earthworms. Some of those from the Auckland Islands, the Campbells, and the Macquaries, belonging to the genus Notiodrij Ins are very closely related to those of j Kerguelen, Marten Island, Falkland IsI lands. South Georgia, Fuegia aud Chili, ,and -Patagonia, to> which,-and to South i Africa, the genus is almost confined. And j similar evidence is yielded by various ! shore-loving marine animals —not only j shellfish, but fishes, of which three com- ' mon genera of the Auckland Islands are characteristically Antarctic; while plants may also be called upon in support of this Antarctic continent. But at the same time it is but fair to state that some of/the facts have been explained in a different manner —namely, by supposing a land bridge passing from the northern part of New Zealand area across Polynesia to South America. This view was ably urged by the late Captain Hntton.- But the majority of recent writers, botanists, geologists, and zoologists, find more and more cogent reason to prefer the Antarctic continent as a means of migration. It must not lie supposed, however, that the outline and extent of the continent is absolutely settled: for we have not yet available proven data as to the depth of the ocean around the Antarctic icecap and the sub-Antarctic islands. I have not I at hand the most recent soundings conj tained in the reports of the various Antarctic expeditions of recent years, but so far as biological evidence goes this is so i strong that the actual outline of the presumed Antarctic continent is of little moment.

New Zealand, with its outlying islands, was once, at no very distant date geologically, a gi%at continent, extending southwards, beyond the Macquarie Islands, and for a brief period was, in all probability, in connection with a great Antarctic continent, and thereby animals were able to pass between New Zealand and South America.