164 report— 1878. 



From the table (p. 162) it may be observed, that of the 39 species, 30 

 (or nearly 80 per cent.) inhabit the Malagasy snbregion, and the Austra- 

 lian region ; and that more than 50 per cent, of the whole are fonnd within 

 the narrow limits of the Malagasy and Austro-Malayan subregions. 



It is worthy of notice, that of the nine species inhabiting the Oriental 

 region, three only can be considered very distinct, and these are closely 

 related to some of the species from the Malagasy and Austro-Malayan 

 subregions, so that it appears evident that the species now inhabiting 

 the Oriental region, were derived at a comparatively recent period from 

 the above-named subregions. 



The sum of the foregoing remarks is well set forth in the second 

 table (p. 163), which exhibits the number of peculiar genera and species 

 of each and of all the families of Chiroptera in each zoological region, 

 and also shows their percentage on the total number of the genera and 

 species. This table also shows that among the Vespertilionidse and 

 Emballonuridaaonly, which are cosmopolitan in their distribution, does the 

 percentage of peculiar species in each zoological region fall below 90, 

 while even in these families it is rarely as low as 70. 



We may now proceed to consider to what extent the recognised zoo- 

 logical regions are severally characterised by the possession of peculiar 

 families, genera, or species of Chiroptera. 



In the first place, the two primary divisions of the earth, Palasogsea 

 and Neoga?a, are well characterised by their Chiropterous fauna : the 

 former by the possession of three peculiar families, the Pteropodida?, 

 Rhinolophidse, and Nycterida?, and by the absence of the Phyllostomida? ; 

 the latter by the absence of the three first-named families, and by the 

 presence of the latter. Although the Vespertilionida? and Emballonuridse 

 are common to both hemispheres, one species only is known with certainty 

 to inhabit both the New and the Old World, and all the genera except 

 three are peculiar. 



The remarkable poverty of the Nearctic and Palasarctic regions in 

 species, and especially in peculiar species, is well shown in the table. 

 In the Nearctic region the number of peculiar species is but one-tenth of 

 those which are characteristic of the closely connected Neotropical region; 

 in the Palasarctic, one-sixth of those in the Ethiopian, and one-seventh of 

 those in the Oriental region. Moreover, the few species which appear to 

 be peculiar to these two regions do not present such marked differences 

 in structure from the species of the adjoining regions as the peculiar 

 species of other regions ; in other words, they are not so characteristically 

 peculiar. This taken into consideration with the comparatively large 

 percentage of non-peculiar species which are found in these and in the 

 adjoining regions, and which extend as a rule into the southern parts only 

 of these regions, shows that the Chiropterous fauna of the Nearctic and 

 Palasarctic regions is mainly, if not wholly, derivative. 



This is precisely what we should have expected theoretically ; for, know- 

 ing that the greater part of the Nearctic and Palsearctic regions was covered 

 with ice at a comparatively recent period, and therefore uninhabitable by 

 a class of animals few of which now extend even in summer as far as the 

 limit of permanently frozen ground, we must suppose that on the cessa- 

 tion of the glacial epoch, these regions derived their Chiropterous fauna 

 from countries lying south of them. 



It appears evident, however, that the Nearctic region has derived 

 many of its species from the Palasarctic, probably by way of Bearing 



