154 Mr, G. E. Dobson on certain Mammals 



zoological regions, being found only in Africa south of the 

 equator, Madagascar, the Mascarene Islands, Australia, and 

 Norfolk Island. The presence of a species of this genus in 

 Norfolk Island and its absence from New Zealand is very 

 remarkable, for, as I pointed out for the first time about ten 

 years ago, one of the two known New-Zealand bats, namely 

 Chalinolobus tuherculatus, is also common in Australia. 



The species of the extraordinarily specialized genus Mega- 

 derma have their head quarters in the Oriental and Ethiopian 

 regions ; yet the largest species, not only of the genus, but 

 also of all known insectivorous bats, namely M. gigas, lately 

 described by the writer from Central Queensland, has its 

 nearest ally, not in any of the Oriental species, but in M. cor 

 from Eastern Africa. Another very remarkable leaf-nosed 

 bat, the type of my genus TricenojjSj found in Madagascar, 

 Eastern Africa, and Persia, but unknown in the well- searched 

 Oriental region, has its nearest and only ally in Rhino- 

 nycteris aurantia of Australia, the type of another very 

 peculiar genus. Finally, Australia agrees much more closely 

 with Madagascar and the Mascarene Islands than with the 

 Oriental region in the species of the large genus Pteropus, 

 for, while species of the section of which Pt. vulgaris of Mada- 

 gascar is characteristic are well represented in the former 

 regions, they are absent from the latter. Furthermore it is 

 noticeable that, while 80 per cent, of the species of the genus 

 inhabit the Australian region and Madagascar with its 

 islands, a single species only has found its way to the great 

 continent of Hindustan and to Ceylon. 



How can we account for this resemblance of the Australian 

 and Ethiopian regions in certain very peculiar species of bats 

 while their birds differ so conspicuously ? 



In the first place, to account for the presence of closely 

 related species in both continents, it is necessary to postulate 

 the existence of some land connexion, not necessarily con- 

 tinuous, between them ; but tiiat such connexion was not by 

 way of India appears evident from the absence of such species 

 in that country or in the islands connecting it and the Malay 

 peninsula with Australia. 



We are therefore obliged to suppose that at a comparatively 

 recent period a chain of islands connected these continents, 

 the islands being sufficiently far apart to prevent the entrance 

 of terrestrial mammals, yet near enough to permit of the 

 occasional passage of some of the flying species ; still it must 

 be remembered that, in estimating such distances, the narrow 

 strait between the Comoro Islands and the coast of Africa, 

 about 180 miles wide, has sufficed to limit the western distri- 



