inhabiting Continental and Oceanic Islands. 157 



group have each two very distinct species, the great continent of 

 India and Burma and the island of Ceylon has but one^. It 

 appears probable^ therefore, that India owes its single flying- 

 fox to some other region, and, in seeking for the country 

 from which it is derived, we must consider its nearest allies 

 among the species of the genus. 



• Now this species differs from Pt. Edwardsii of Madagascar 

 and the Seychelle Islands in few and unimportant characters, 

 presenting such differences only as might have resulted in a 

 few generations, though they now appear to be permanent. 

 It is therefore evident that these two species have been 

 derived within a comparatively recent period from a common 

 ancestor, and probable that the enormous number of individuals 

 of Pt. medius now representing the genus in India are the 

 descendants of a few individuals originally escaped from their 

 island homes in the Indian Ocean, and now cut off by sub- 

 sidence of some of these islands from their nearest relations. 

 On no other hypothesis can we account for the discontinuous 

 ■distribution of the species of this genus, for, as we have seen, 

 the narrow channel of Mozambique between the Comoro 

 Islands and the coast of Africa has sufficed to prevent their 

 entrance into Africa, where tree-fruit is abundant and where 

 immense numbers of fruit-eating bats of other and of allied 

 genera abound. Indeed it is difficult to imagine one of 

 these great bats, whose flight appears so slow and laboured 

 compared with tiiat of all other species of Chn-optera, traver- 

 sing 50, much less 500, miles of unbroken sea ; for even if 

 carried out to sea by a storm, their wings would evidently 

 collapse long before they had travelled half the distance. On 



• That this is not due to deficiency of food the following note by Dr. 

 J. Anderson, F.R.S., abundantly proves, for it shows what prodi""-ious 

 numbers of individuals of this one species (Pt. vwdius) inhabit the 

 country : — " This species has been Hying for the last few days from the 

 north to the south of the city (Calcutta), in immense numbers, imme- 

 diately after sunset. The sky, from east to west, has been covered with 

 them as far as the eye could reach, and all were flying with an evident 

 purpose, and making for some common feeding-ground. Over a trans- 

 verse area of 2')0 yards, as many as seventy bats pissed overhead in one 

 minute ; and as they were spread over an area of great breadth and could 

 be detected in the sky on both sides as far as could be seen, their num- 

 bers were very great, but yet they continued to pass overhead for about 

 half an hour. This is not the first time I have observed tliis habit in 

 this species ; indeed it was more markedly seen in August 1(SG4^ while 

 I was residing in the Botanical Gardens, Calcutta. The sky, immedi- 

 ately after sunset, was covered with this bat, travelling in a steady 

 manner from west to east, and spread over a great expanse, all evidently 

 making for one goal, and travelling, as it were, like birds of passage, with 

 a steady purpose." (' Catalogue of Mammalia,' ludian Museum, Calcutta, 

 pt. i. p. 101 : 1881.) 



