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been disputed, a great amount of similarity between the Nearctic and Palæarctic faunas, but not enough to justify the junction of these two great land-masses into one “Region” or “Realm.”
As for the so-called “ Arctic realm,” which consists of the land bordering the Polar Ocean and Hudson's Bay and the great peninsula of Greenland,“ beyond the limit of arboreal vegetation,” together with the similar Arctic portion of the old world, Mr. Allen states, no doubt correctly, that it contains a “homogeneous hyperborean fauna of circum-polar distribution.” But looking to the extreme poverty of life in these inclement latitudes, as Mr. Allen well puts it, it seems to be quite unnecessary to elevate this wretched fraction of the Earth's surface into one of its principal constituent life-regions. The plan adopted by Mr. Wallace, of regarding it as a borderland between the Nearctic and Palæarctic Regions is far preferable.
The question of the recognition of Madagascar and New Zealand as independent regions will be further discussed in the articles on the Ethiopian and Australian Regions respectively, as will also the propriety of dividing the Neotropical into two separate regions. A few words, however, may be said here with regard to Mr. Allen's proposal to join together the Oriental and Ethiopian Regions into one “Realm.”
According to the estimate given below (Table I., p. 16), the total number of genera found in the Oriental Region is 113, and of these thirty-nine are not found elsewhere. Of the balance—seventy-four-eight only are common to the Oriental and Ethiopian Regions, and are not found in any other Region, whereas twenty-eight more, also known
These are Manis, Rhinoceros, Elephas, Golunda, Atherura, Viverra, Mellivora, and Nycteris.
in the Oriental and Ethiopian Regions, are likewise found in the Palæarctic Region. Furthermore, out of the eight genera above mentioned, although they are not now found in the Palæarctic Region, four of them are known to have existed there during the Pliocene period. This shows, we think, very conclusively that what small resemblance there is between the mammals of the Oriental and Ethiopian Regions is due rather to a similarity in their origin, than to any sort of direct connection between the two regions.
To sum up the subject we add a table of the numbers of orders, families, and genera of mammals found in the six different Regions, together with the number of genera confined to them (endemic), the number of those slightly transgressing the Regional borders (quasi-endemic), and the number of those of wide-spread distribution in each Region. In the second table these numbers have been reduced to percentages, which give in some respects a better idea of the relative specialisation of the mammalfauna of each Region. On examining these tables, it will be seen that the Ethiopian Region stands second in point of the number of genera confined to it, coming next to the Neotropical Region.
The lists of genera from which this table has been worked out are based on those adopted in Flower and Lydekker's (3) standard work on mammals, with a certain number of additions and corrections. In consequence of this the figures in the case of the Nearctic Region will not be found to exactly correspond with those quoted from Mr. Allen above (2). It must also, of course, be understood that the figures are merely approximate, and liable to continual alterations as new discoveries are made.
Approximate Numbers of Families, Genera, and Species of
Mammals in the six Regions.
Numbers given in Table I. reduced to Percentages of Total
Numbers of Families and Genera.
31 35 23 5 9 0
46 71 91 90 100
60 79 66 34 30 24
7 11 2 8 3 3
The groups entirely confined to each region are classed as “endemic”; those that cross the frontiers slightly as “quasi-endemic”; all others are considered as "wide-spread.”
The percentages, it will be observed, on account of the omission of fractions, do not exactly make up one hundred in every case.