chap, ix.] INDO-MALAT ISLANDS. 225 



I will now give two examples to show how a know- 

 ledge of the distribution of animals may reveal unsus- 

 pected facts in the past history of the earth. At the 

 eastern extremity of Sumatra, and separated from it by a 

 strait about fifteen miles wide, is the small rocky island of 

 Banca, celebrated for its tin mines. One of the Dutch re- 

 sidents there sent some collections of birds and animals 

 to Leyden, and among them were found several species 

 distinct from those of the adjacent coast of Sumatra. One 

 of tbese was a squirrel (Sciurus bangkanus), closely allied 

 to three other species inhabiting respectively the Malay 

 peninsula, Sumatra, and Borneo, but quite as distinct from 

 them all as they are from each other. There were also two 

 new ground thrushes of the genus Pitta, closely allied 

 to, but quite distinct from, two other species inhabiting 

 both Sumatra and Borneo, and which did not perceptibly 

 differ in these large and widely separated islands. This is 

 just as if the Isle of Man possessed a peculiar species of 

 thrush and blackbird, distinct from the birds which are 

 common to England and Ireland. 



These curious facts would indicate that Banca may have 

 existed as a distinct island even longer than Sumatra and 

 Borneo, and there are some geological and geographical 

 facts which render this not so improbable as it would at 

 first seem to be. Although on the map Banca appears so 

 close to Sumatra, this does not arise from its having been 



VOL. I. Q 



