, ON THE GEOGRAPHICAL DISTRIBUTION OF THE CHIROPTERA. 159 



North American species either regularly or occasionally visit the Ber- 

 mudas, a distance of 600 miles from the mainland." 



I do not think that the occurrence of two American species of bats in 

 the Bermudas affords much proof of the general capability of the species 

 of Chiroptera in traversing considerable spaces of sea, for it is exceedingly 

 probable that the few individuals which have been noticed there have 

 been carried thitber by storms (to which cause is evidently due the great 

 number of straggling species of birds which have been found there), or 

 have been imported into the island while hybernating in the holds of 

 vessels, or are the descendants of such accidentally imported individuals. 

 However, even if it be granted that the Chiroptera possess great powers 

 of dispersal, it is certain that quite nine-tenths of the species avail them- 

 selves of them in a very limited degree indeed, and it is significant that 

 the distribution of the species is limited by barriers similar to those which 

 govern it in the case of other species of mammals. This is well shown 

 by the small number of species which are known to inhabit more than 

 one of the recognised zoological regions, which amount to 22 only out 

 of 400. The following list includes these species, and shows also their 

 distribution. 



1. Pterojnis hypomelanus Australian and Oriental. 



2. Maeroglossus minimus Oriental and Australian. 



i 3. Rhinolophus ferrvm-eqwmwm Ethiopian and Palasarctic. 



4. Vesperugo serotinus All regions except the Australian. 



5. Vesperugo noctula Ethiopian, Oriental, Palasarctic. 



6. Vesperugo maurus Oriental and Palasarctic. 



7. Vesperugo abranms Oriental and Australian. 



8. Vesperugo Kuhlii . . Oriental and Palasarctic. 



9. Nycticejus crepuscularis Nearctic and Neotropical. 



10. Atalapha noveboracensis Nearctic and Neotropical. 



11. Atalapha cinerea Nearctic and Neotropical. 



12. Htvrpioceplialus luwpia Oriental and Australian. 



13. Vespcrtilio adversus Oriental and Australian. 



14. Vespcrtilio capaccinii Oriental and Palasarctic. 



15. Vespcrtilio daubcntonii Palasarctic and Oriental. 



16. Vespertilio murieola Oriental and Australian. 



17. Vespcrtilio lucifugus Nearctic and Neotropical. 



18. Kerivoula hwdivichii Oriental and Australian. 



19. Miniopterus schreibersii Oriental, Australian, Ethiopian, and 



Palasarctic. 



20. Taphozous nudiventris Ethiopian, Oriental, and Palasarctic. 



21. Shitwpoma microphyllum Ethiopian, Oriental, and Palasarctic. 



22. Nyctinomus brasiliensis Neotropical and Nearctic. 



Estimating the total number of known species of Chiroptera at 400, it 

 follows that 5^ per cent, only wander beyond their respective zoological 

 regions, or, in other words, 94^ per cent, are characteristic. It is also 

 noticeable that more than two-thirds of these wandering species belong 

 to the family Vespertilionidae, which has by far the widest geographical 

 distribution, and includes the least specialised forms. 



The following table exhibits the numbers of families, genera, and species 

 inhabiting each zoological region ; and shows that in the regions situated 

 principally within the tropics (as the Oriental and Neotropical regions) 

 the number of species is more than three times that of those lying chiefly 

 in the temperate zones (as the Nearctic and Palsearctic regions). 



