[2 



KNi n ANDERSEN 



(184) 



Microchiroptera from the islands examined by Mr. Miller himself, 

 and he found them to be different from the mainland species. To 

 these must now be added Rhinolophus cognatus, as a bat closely 

 allied to, but specifically different from, a Malacca species ( 1 ). 



To sum up : — All the species of Microchiroptera from the 

 Andamans and Nicobars (five out of the nine recorded) which 

 have been sufficiently closely examined have proved to be related 

 to, hut to a more or less pronounced degree different from, 

 the mainland species. This is precisely what we should expect 

 if their origin dates bach to the period of land connection; 

 long and complete separation from the main stem, combined with 

 the influence of insular isolation, has brought the latent tendency 

 1<i variation in the species into activity; but neither has the sepa- 

 ration been long enough, nor the difference in milieu great enough, 

 to obscure their true origin. — But it is certainly not what we 

 should expect to be the case if these bats simply in very recent 

 time had immigrated from the mainland. 



In general works on the geographical distribution of mammals 

 bats are either put aside as more or less untrustworthy guides 

 for the zoogeographer or entirely left out of consideration; they 

 arc supposed to possess in their power of flight a means of 

 dispersal essentially different from those of other mammals, 

 enabling them to rather easily cross channels of water 1 hat would 

 form effectual barriers to the dispersal of other mammals; and 

 they are consequently thought to be of comparatively little im- 

 portance from a distributional point of view. There can be small 

 doubt that this theory of an intermigration of bats between islands 

 which are not within easy reach of each other requires, to 

 say the least , considerable restriction. We have just seen that 

 Ihe Microchiroptera of the Andamans and Nicobars show that 

 degree of differentiation which we might anticipate in view of 

 their continental origin and subsequent insular isolation in a 

 milieu not very different from that of the mainland, but decidedly 

 not what we should expect if, after the separation of the 

 Archipelago , a more or less frequent intermigration 



0) i have not, included the Megachiropteraofthe Archipelago in this brief review, 

 <>nl> liccniisi in... I <>( Hi. in are Inn inipcWtrtly know n. si\ species have lieen recorded; 

 three of lliein are apparently autochthonous; the others have, for reasons anything 

 but conclusive, been identified with species also occurring elsewhere in the Oriental 

 region. 



