GEOGRAPHICAL DISTRIBUTION. IxXvii 



over India, Ceylon, Indo-China, and Indo-Malaya (now six species, 

 fourteen forms), or " Rhhiolopfms ferrum-equiniim" uniformly over 

 Europe, Asia, and Africa (now numerous distinct forms), they were 

 undoubtedly of questionable value as zoogeographical material, 

 liut these and similar anomalies invariably disappear as soon as 

 modern methods of discrimination apijlied on vastly increased 

 material render it possible to draw the lines of separation between 

 the species (and their local modifications) somewhat more closely 

 in accordance with the lines drawn by Nature. The second argu- 

 ment referred to above, that the spreading of Bats from one locality 

 to another must obviously have been greatly facilitated by their 

 possession of wings, may in theory appear plausible enough, but 

 when tested on the actual distribution of the species and subspecies 

 it proves to be of much less importance than commonly supposed ; 

 it rests, in reality, on a confusion of two different things : the 

 j)Ower of flight no doubt would enable a Bat to spread over a much 

 larger area than non-fiying Mammalia, but, as a matter of fact, 

 only in very few cases is there any reason to believe that it has 

 caused it to do so. The following pages, in which the distribution 

 of the Alegachiroptera within each zoogeographical region or sub- 

 region is discussed in some detail, will give ample evidence to this 

 effect, but a few of the more striking examples may be mentioned 

 here : a species of Pleroj)us inhabits the island of Pemba, south of 

 Zanzibar, but although this island is separated from Africa by 

 a channel only o5-40 miles wide, not this particular species only 

 but the whole genus is unknown from any part of the adjacent 

 continent ; although absent from Africa the genus Pteropus is 

 distributed all over the Malagasy region, and each group of 

 islands (Madagascar, Comoros, Aldabra, Seychelles, Mascarenes) has 

 its own peculiar species, intermigration between the groups of 

 islands is unknown ; the Epomophorine section of Fruit-bats is 

 distributed over the whole of the Ethiopian region (eight genera, 

 nineteen forms), but not a single form has spread to any island of 

 the Malagasy region ; the Fteropus melanotiis group of species 

 is distributed over the Andamaus, Nicobars, Nias, Engano, and 

 Christmas Island (south of Java), and the whole group is confined 

 to this chain of islands, no form having spread to the neighbouring 

 Malay Peninsula or Sumatra; Fteropus hi/pomeJanus is represented 

 by a local form in Engano, off Western Sumatra, but the species, 

 though widely distributed elsewhere in Indo-Malaya, is unknown 

 in Sumatra and Java ; the Megachiropteran fauna of Ceylon shows, 

 of course, very close affinities to that of the Indian Peninsula, but 

 the Indian llouseittis lesclienanlti is replaced by a distinct species 

 {seminudus), and the Indo-Chinese and Indo-Malayan Cynopterus 

 hrachi/otis is represcntea by a local form, though the species is 

 unknown in the Peninsula ; the Eruit-bat faunas of the Malay 

 Peninsula, Sumatra, and Borneo are closely interrelated, like their 

 Mammalian faunas in general, but each has some distinct autoch- 

 thonous forms of Eruit-bats (Borneo even two autochthonous 

 genera), as it has of other ifammalia ; the Javan Mammalian fauna in 



