KSl'O AXDERSEN 



Mierocliiroptera from tlie islands examined by Mr. Miller himself, 

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

 tliese nuist now be added Rhinolophus cognatm, as a bat closely 

 allied to, i)ut specifically different from, a Malacca species (^). 



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

 Andamans and Nicol )ars (live out of the nine recorded) which 

 have been sutiiciently closely examined have proved to be related 

 to, but to a mo7^e or less pronounced degree different from, 

 the mainland species. This is precisely lohat toe sliould expect 

 if their origin dates hack 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 

 to 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 

 are 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 that 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 

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

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

 the 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 



(1) I have not included the Megachiroptera of the Archipelago in this brief review, 

 only because most of them are too imperfectly known. Six species have been recorded; 

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

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

 region. 



