1873.] a. E. Dobson— O;^ the Pteropidde of India. 195 



It is very remarkable that, supposing the localities to be correct or 

 approximately so, one half of the whole number of species is distributed 

 among the small islands of the Malay Archipelago, while a single species — 

 JPteropus medius — is the sole representative, hitherto discovered, of the 

 genus in the Continent of India and Burma. 



That a large proportion of the species should be found in the Malay 

 Archipelago and adjoining Islands might be expected, as these animals like 

 monkeys can live only where a constant supply of fruit is attainable through- 

 out the whole year, but the same conditions obtain in the greater part of 

 the Peninsula of India, and especially in Equatorial Africa, yet scarcely one- 

 seventh of the whole number has been found in these regions. 



The Malay Archipelago is, therefore, either the original and special 

 home of the genus from which a few species have wandered into" India and 

 Africa, or many species remain undiscovered in the latter countries, and 

 probably many of the so-called species which go to make up the large 

 number from Malayana have been founded on insufficient grounds. 



I hcive not the least doubt that the real number of species is much less 

 than that recorded, and that many described as new by Temminck and 

 others will, with the accession of additional and more perfectly preserved 

 specimens to the collections hitherto available in our Museums, be found 

 referable to a few really distinct species. This may be especially expected 

 in the case of those species that have been founded on differences in the 

 colour of the fur, which appears to have been regarded by some zoologists 

 as of equal importance with the colour of the feathers in birds. 



I have elsewhere* dwelt at some length on the variability of the colour 

 of the fur in many species of bats, and have shown that, in the Pteropi 

 especially, individuals belonging to the same species present very different 

 shades of colour according to sex age and season, and probably also, but in 

 a less degree, according to locality. 



Differences in the form of the skull and in the teeth have been also 

 used to distinguish the species, but these, though of the greatest importance, 

 are not satisfactory, if alone available as a means of diagnosis, for it should, 

 surely, be possible to distinguish the species of a given vertebrate animal 

 without first finding it necessary to kill and make a skeleton of it. 



It is, therefore, desirable that, in the description of species, certain 

 external characters may be given from which the living animal can be 

 known, and these, I believe, may be found in the shape and relative size of 

 the ears, and in the quality and distribution of the fur. 



In all the Chiroptera, we find one or more of the organs of special sense 

 greatly developed to supplement or, in some genera, almost wholly replace 

 the visual organs (which in most cases are very rudimentary or, where 

 * Proc. Zool. Soc. of Loudou, 1873. 



