PART II. 

 HISTORICAL AND GEOGRAPHICAL. 



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 

 features 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. Sclater. 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 denned 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 Sclater 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, Falkland Islands. 

 Approximate area : 5,500,000 square miles. 

 Number of species : 2250. 



The first four of these regions Dr Sclater grouped together to form 

 the great division Palseogaea, 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 Giinther. Here it was shown that the division of the earth as 

 proposed by Dr Sclater, 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 Heteromorphse), 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 Sclater, adopting 

 these as subdivisions, while the Notogsea were divided into three provinces ; 

 (1) Austro-Columbia ( = Neotropical); (2) Australasia (equivalent to the 

 Australian region of Sclater 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. Sclater 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 Giinther on Fishes. In the latter work various zoological reoions 

 and sub-regions were proposed for use in connection with the class of animals 

 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 ; dividing 

 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 independ- 

 ently 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 F. E. Beddard appeared under the title, 

 A Text-book oj 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 



