Page:Encyclopædia Britannica, Ninth Edition, v. 3.djvu/755

DISTUIBUTION.] B I K D S 737 evidence, which is from one point of view so evidently deficient, may not be supplied by inquiry into existing uvifaunce , and this, in other words, signifies that a know ledge of the Geographical Distribution of living Birds becomes a matter of prime necessity to every one who would intelligently exercise the calling of an ornithologist. Thus driven to a kind of extremity, the student of Birds, however, cannot but regard with the most lively satisfac tion the circumstance that to one of his brethren is due the merit of having first truly pointed out the great Zoogeo- graphical Regions of the globe a fact not a little surpris ing when we reflect that the outlines of Distribution laid down in 1857 by Mr Sclater 1 had reference only to the most vagrant Class of animals in creation ; yet these out lines have, not merely in the main, but to a very great extent in detail, met with the approval of nearly all those zoologists who have since studied the subject in its bear ing upon the particular Classes in the knowledge of which they themselves stand pre-eminent. Without infringing upon what must be deemed the generalities of biological Distribution, it is proper to observe that Mr Sclater s success is to be attributed to the method in which his investigations were carried on a method in which he had but few predecessors. Instead of looking afc the earth s surface from the point of view which the geographer would take of it (a point of view which had hitherto been adopted by most writers), mapping out the world according to degrees of latitude and longitude, determining its respective portions of land and water entirely regardless of the products of either element, or adhering to its political divisions time-honoured as they were, lie endeavoured to solve the question simply as a zoologist should, by taking up the branch of the subject with which he was best acquainted, and by pointing out and defining the several Regions of the globe in conformity with the various aspects of ornithic life which they present. But herein there was at once a grave difficulty to be encountered. Birds being of all animals most particularly adapted for extended and rapid locomotion, it became necessary for him to eliminate from his consideration those groups, be they large or small, which are of more or less universal occurrence, 2 and to ground his results on what was at that time commonly known as the order Insessores or Passeres, comprehending the orders now generally dif ferentiated as Passeres (verce), Picarice, and Psittaci. On this basis then Mr Sclater was enabled to set forth that the surface of the globe exhibited six great Regions, each in a marked manner differing from all the rest, though the difference was not always equally important. These Regions he termed respectively the Palaearctic, Ethiopian, Indian, Australian, Nearctic, and Neotropical ; and though it is on all accounts better to preserve the names he bestowed on them, it does not seem convenient to follow the order in which he placed them. Thus the Australian Region appears not only to differ more from the others than they do among themselves, but its differences are of a kind which, when its fauna is considered as a whole, suggest a striking peculiarity, namely, that many of the forms of animal life therein found are the direct and not very much modified descendants of types which may very likely at an early period of our planet s history have pre dominated over every land, but of types which have since 1 Jmffnal of the Proceedings of the Linnean Society, Zoology, ii. pp. 130-145. It is muck to be regretted that the author of this most valuable essay has never sanctioned its republication in another and improved form. Many of its details, and some of its principles even, are now known to be incorrect, but for the time at which it ap peared it was a marvellous production. s Not but that even in the most widely-spread groups are contained r&gathers sub-families, genera, or species strictly limited to certain localities. . Some of these will be noticed further on. been elsewhere in great part replaced by more highly developed structures. The lower rank in the scale of its most characteristic animals seems to be indisputable, and, therefore, with the Australian Region it appears most proper to begin. 3 I. THE AUSTRALIAN REGION is most trenchantly divided AUSTUA- from the Indian, which, from a geographical and possibly LIAN from a geological point of view, seems to be conterminous REQION - with it, by the narrow but deep channel which separates the small islands of Bali and Lombok, and will be found Boundar to determine the boundary between two entirely distinct portions of the earth s surface. Midway along this channel we may draw a line in our imagination, and continue it in a north-north-easterly direction up the Strait of Macassar, dividing the much larger islands of Celebes and Borneo. A considerable interchange of animal forms in the two islands last named is indeed to be observed, and even a slight intermingling of the productions of the two former seems now to be going on ; but the inosculation is so much less in degree than that which obtains between any other two Regions, while the characteristic, not to say peculiar, zoological types which occupy either side of this line are so divergent, that it may be fairly considered a harder and faster line than any that can elsewhere be found. Between Wallace Bali and Lombok, as above stated, it has been shewn by Line - Mr Wallace to be all but perfect, and in his honour this boundary, as real in the abstract as though it existed in the concrete, has been most justly named after the naturalist and traveller who first saw and recognized its importance " Wallace s Line." 4 As above indicated, this line becomes less definitive as it proceeds further northward*; and though we know it to pass between the Philippine Islands and Sanguir, and again between the former and the Palau group, its further progress in that direction cannot as yet be set down with precision, though it pro bably runs to the westward of the Ladrones. But here abouts we lose sight of it, until we arrive at the Sandwich Islands, to the northward of which it must pass, since for reasons presently to be given at greater length that archi pelago must be confined within the Australian Region. Southward from Lombok the boundary of the Region rounds the western coast of Australia, and then strikes off in a south-easterly direction to encompass New Zealand and its dependencies. Arrived here it must be drawn so as to include all of what is commonly known as Polynesia, though the characters of the intermittent chain of islets lying parallel to and just to the southward of the Tropic of Capricorn, and a few scattered reefs to the northward of the equator (between long. 108 and 115 W.), are at present insufficiently determined. After encircling, how ever, the Low Archipelago and the Marquesas, the boundary trends to the north-west, and includes, as before stated, the Sandwich Islands ; but thence its precise direc tion cannot now be traced, owing to the obscurity which veils the numerous islets of the North Pacific Ocean, which 3 The writer has to acknowledge with hearty thanks the very singular mark of confidence conferred on him by his eminent friend Mr A. R. Wallace, who has allowed him to peruse in manuscript the greater part of a work on the Geographical Distribution of Animals, the early publication of which can hardly fail to place this most interesting subject in the position it undeniably deserves, but a position to which it has never yet attained through the absence of any treatise of like character. The value of the favour thus bestowed upon him the writer cannot overestimate. 4 This name was first given by Professor Huxley (Proc. Zool. Soc. 1868, p. 313), but as it is hardly a geographical term, it will accord ingly make no appearance on any save a so-called " physical " map. The value of the discovery above mentioned, of which no one had ever dreamt till it was made by Mr Wallace, seems to justify proper notice from chartographers, and it might be well, therefore, to dignify the channel between Bali and Lombok named on some maps Lombok Strait by the appellation of "Wallace s Strait."

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