NEW OR LITTLE-KNOWN' BATS 



13 



between the mainland and the islands had taken place. A 

 series of similar instances , from the same region of the earth , 

 might be adduced: — Rh. calypso in Engafio, Rh. circe in 

 Nias , Rh. sumatranus in Sumatra : each of these three neigh- 

 bouring islands is inhabited by a distinct modification of the same 

 type of Rhinolophus (the Rh. acuminalus type); Rh. trifoliatus 

 niasensis in Nias, Rh. trifoliatus typicus in Sumatra; Rh. soli- 

 tar ius in Banka, Rh. trifoliatus in the Malay Peninsula and 

 Sumatra; Rh. nereis in the Anambas Islands, RJi. stheno in the 

 Malay Peninsula; Rh. affmis nesites in the N. Natunas, Rh. 

 afftnis superans in the Malay Peninsula. It will be noticed that 

 all these islands and countries, though situated close together, are 

 inhabited by different species of the same type, or by different 

 local representatives of the same species; the fact would be dif- 

 ficult to explain on the supposition that bats are liable to cross 

 water of considerable width; but it is easily understood when we 

 bear in mind that all the small islands mentioned have a geolo- 

 gical history of their own, to a certain extent different from that 

 of the adjacent islands or mainland. — On the other hand, there 

 is a great similarity between the bat fauna of Borneo and Malacca, 

 of the Karimata Archipelago and Borneo, of Sumatra and Malacca; 

 these countries are separated by comparatively shallow water, 

 and such species as are common to all , or several , of them no 

 doubt date back to the time of actual land connection. 



So far the facts and their probable explanation. But those who 

 are inclined to think that the present distribution of bats has to 

 any marked degree been influenced by their power of flight, will, 

 so far as I can see, have to confront also another series of dif- 

 ficulties, of a more theoretical kind. Bats (Microehiroptera) find 

 their food inland or flying along the shore in the closest proxi- 

 mity to land; apart from the exceedingly few species known to be 

 truly migratory, they have no reason to venture out over the 

 open sea far from their haunts, and probably they never do so 

 deliberately. It might be argued that a gale can easily carry a 

 flying animal from one island to another even if they are sepa- 

 rated by water of considerable width ; but it should not be for- 

 gotten that under an athmospheric disturbance strong enough to 

 deprive the bats of the control of their wings, these delicate and 

 sensitive mammals would, most probably, not fly at all, but 



