PART II.
HISTORICAL AND GEOGRAPHICAL.
The first four of these regions Dr Selater grouped together to form the great division Palamgsea, while the remaining two formed the division Neogsea.
The publication of this important paper gave a great impetus to the study of the subject, and it was followed immediately by a paper on Reptiles by Dr Günther. Here it was shown that the division of the earth, as proposed by Dr Selater, answered admirably for Reptiles. A few years later (1866), Andrew Murray gave to the world a large volume on The Geographical Distribution of Mammals. This author contended that only four primary regions could be established for Mammals, the Indian and Ethiopian being united, and likewise the Nearctic and Neotropical.
In 1868 Huxley contributed a paper on the classification and distribution of the Gallinaceous Birds (Alectoromorphse and Heteromorphie), in which he suggested the division of the earth into two primary divisions, a northern called Arctogsea and a southern called Notogsea. In the former he placed the Nearctic, Palsearctic, Ethiopian, and Indian regions of Selater, adopting these as subdivisions, while the Notogsea were divided into three provinces : (1) Austro-Columbia (־Neotropical); (2) Australasia (equivalent to the Australian region of Selater minus New Zealand); and (3) New Zealand. Besides forming a new province for New Zealand, Huxley advocated the separation of a circumpolar region. His scheme, however, has received little support, and the regions proposed are regarded as disproportionate and inconvenient.
During the next three years papers were published by W. T. Blanford, E. Blyth and J. A. Allen, and then in 1876 appeared Alfred Russel Wallace’s classical work, The Geographical Distribution of Animals, an elaborate and exhaustive treatise in two volumes, which still remains the standard authority on the subject as a whole. In this important publication the various systems hitherto proposed are carefully discussed, and the original six regions of P. L. Selater adopted as most suitable for general purposes (see Plate 1). The name “ Oriental ” is substituted for “ Indian ” in Region III., and each region is further divided into four sub-regions, which are shown on carefully
prepared coloured maps. The work is arranged in four parts:______Part I.
treats of the Principles and General Phenomena of Distribution • Part II deals with the Distribution of Extinct Animals; Part III. is devoted to Zoological Geography, and gives an exhaustive review of the various regions and sub-regions; while Part IV. concludes the work with an account, in systematic order, of the distribution of all the families and most of the genera of the higher animals, together with certain Insects and Molluscs.
During the next four years (1877-1880) several important contributions to the subject appeared, including a volume by Wallace on Island Life and one by Dr Günther on Fishes. In the latter work various zoological regions and sub-regions were proposed for use in connection with the class of anfmals concerned. In 1887 Dr Angelo Heilprin published an important, though not a large volume on the general subject. Adopting a suggestion of Professor Alfred Newton’s, Heilprin unites the Nearctic and Palsearctic regions into one huge “ Holarctic ” realm, separates off a “ Polynesian ” realm and suggests the use of three “transition” tracts, viz.: (a) Tyrrhenian or Mediterranean, between the Palsearctic (Eastern Holarctic) and Ethiopian realms; (b) Sonoran or American, between the Nearctic (Western Holarctic) and Neotropical realms; and (c) Papuan or Austro-Malaysian, between the Oriental and Australian realms.
In 1890 Dr W. T. Blanford, in his Anniversary Address to the Geological Society of London, proposed the adoption of the following three regions: (1) Australian; (2) South American; and (3) Arctogean; dividin״ the last-named into Malagasy, Ethiopian, Oriental, Aquilonian (= Palsearctic and northern part of Nearctic), and Medio-Columbian (־Sonoran) sub-regions. Two years later the American zoologists, Dr J. A. Allen and Dr C. Hart Merriam, contributed important memoirs on the subject, with especial reference to the Mammals of North America, while the following year (1893) an anonymous writer in Natural Science proposed the use of the terms Notogsea, Neogsea and Arctogsea for Dr Blanford’s three principal divisions. In the same volume appeared a paper by Dr R. Bowdler Sharpe entitled “On the Zoo-Geographical Areas of the World, illustrating the Distribution of Birds.” In this contribution the usual six regions are adopted, but they are divided into an unusual number of sub-regions. The author advocates the working out of statistics by specialists quite independently of each other, and the future correlation of results.
Professor Alfred Newton, in an important article on “Geographical Distribution” in the Dictionary of Birds (1893), urges the recognition of New Zealand as a primary region, and adopts Heilprin’s “Holarctic” realm. He therefore uses the following six regions:—(1) New Zealand• (2) Australian; (3) Neotropical; (4) Holarctic; (5) Ethiopian; and (6) Indian.
In 1895 a useful little book by E. E. Beddard appeared under the title A Text-book of Zoogeography, and the following year saw the publication of an important volume by R. Lydekker on A Geographical History of Mammals. In the latter work special prominence is given to the study of fossil forms, and the deductions which may be drawn from them. The information given in its pages presents the subject in a different light from
ZOOGEOGRAPHICAL REGIONS.
Owing to the peculiarities of distribution shown by animals at the present day, it has been found practicable, and indeed advisable, to divide the whole surface of the earth into a number of regions, quite independent of mere geographical considerations, each of which is characterised by certain features of its own, such as the presence or absence of particular groups of animals, or the predominance or otherwise of certain others. But all classes of animals are not distributed according to the same plan, and hence it is not possible to adopt any single scheme which shall be equally applicable to all. Every specialist naturally follows the divisions and boundaries indicated by his own particular group, and hence a large number of schemes have been proposed, each one of which is specially adapted to a certain class of animals.
The general student is therefore brought face to face with the question as to what scheme is the best to adopt for ordinary purposes. By a general consensus of opinion, the highest class of animals, the Mammals, are judged pre-eminently suitable for this end. The reasons for this selection have been admirably summed up by Wallace, our leading authority on the subject; and they may be here briefly recapitulated. In the first place, the abundance of the fossil remains of Mammals, and the amount of knowledge of them that we consequently possess, show us more fully than does any other group the featuies of distribution in past ages; while the careful study of such remains, added to that of existing forms, has rendered their classification, which is one of the most important adjuncts to the study of geographical distribution, much more accurate and natural than that of any of the other classes. Moreover, the limited means of dispersal possessed by Mammals, their high organisation and their powers of adaptation, render them less dependent upon particular kinds of food or upon particular conditions of existence, and place such animals before all others in their suitability for the purpose we have indicated.
Before treating of the zoological regions in detail, it may be well to place before the reader a concise history of the subject, and this, coupled with a reference to the bibliography given in Part IV., will enable him to pursue the study more closely and logically hereafter, should he elect to do so.
The first attempt to map out a number of zoogeographical regions, based upon the actual distribution of species, and apart altogether from purely geographical considerations, was made by Dr P. L. Selater. This eminent zoologist, who is fortunately still living, read a paper before the Linnean Society of London, in June 1857, entitled “On the General Geographical Distribution of the Members of the Class Aves.” Taking as his basis the Passerine, or “Perching” Birds, he proposed the division of the earth into six great regions, which he defined geographically, and whose area in square miles he roughly estimated. At the same time, he furnished a tabulated statement of the number of species found in each region, and an indication of the peculiar and characteristic genera. As this paper was an epoch-making one, and as its divisions correspond very closely with the main regions adopted in most of the schemes since proposed, it is perhaps desirable to quote the main features before proceeding further.
The regions proposed by Dr Selater were as follows.:_
I.	Palsearctic. Extent: Africa north of the Atlas, Europe, Asia
Minor, Persia and Asia generally north of the Himalaya range, upper part of the Himalaya range (?), Northern China, Japan and the Aleutian Islands.
Approximate area : 14,000,000 square miles.
Number of species : 650.
II.	.¿Ethiopian or Western Palseotropical.—Extent: Africa south
of the Atlas range, Madagascar, Bourbon, Mauritius, Socotra, and probably Arabia up to the Persian Gulf, south of 30° N. lat.
Approximate area: 12,000,000 square miles.
Number of species : 1250.
III.	Indian or Middle Palseotropical.—Extent: India and Asia generally south of Himalayas, Ceylon, Burmah, Malacca and Southern China, Philippines, Borneo, Java, Sumatra and adjacent islands.
Approximate area : 4,000,000 square miles.
Number of species : 1500.
IV.	Australian or Eastern Palseotropical.—Extent: Papua and adjacent islands, Australia, Tasmania and Pacific Islands.
Approximate area: 3,000,000 square miles.
Number of species : 1000.
V.	Nearctic or North-American.—Extent: Greenland and North
America down to centre of Mexico.
Approximate area : 6,500,000 square miles.
Number of species : 660.
VI. Neotropical or South-American.—Extent: West India Islands, Southern Mexico, Central America and whole of South America, Galapagos Islands, Ealkland Islands.
Approximate area : 5,500,000 square miles.
Number of species : 2250.
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