THE PIPISTRELLE, NOCTULE, AND SEROTINE 279 



observers will readily discriminate between these bats, even when on the wing, from 

 their difference of habit and mode of flight. "Whilst the noctule," observe the 

 authors of Bell's British Quadrupeds, "may throughout the whole of the summer 

 be seen taking its regular evening flight, night after night, near the same spot, the 

 L,eisler's bats, on the contrary, will be seen once, perhaps for a few minutes only, 

 and then lost sight of. It appears to affect no particular altitude in its flight, any 

 more than it preserves a regular or prescribed beat. When the weather is fine, you 

 may see this bat passing on in a kind of zig-zag manner, apparently uncertain where 

 to go; generally, although not always, at a considerable elevation, and in a few 

 minutes it is gone." I^ike the noctule, the hairy-armed bat has a wide geographical 

 distribution, ranging through Europe and the temperate regions of Asia, and having 

 been recorded from one locality in the Himalayas. 



The serotine ( V. serotinus) is another large British bat belonging to 

 a group distinguished from that containing the preceding species by 

 the premolars in the upper jaw being reduced to one on each side. This bat has 

 ears of moderate size, with broadly-rounded tips, and the tragus broadest just above 

 the base, and thence gradually diminishing in width to the rounded tip. The gen- 

 eral color of the fur is chestnut brown above, and yellowish gray on the under parts ; 

 the hair being long and silky, and the wing membranes dark brown, or nearly black. 

 There is, however, some degree of individual variation in color, specimens being 

 occasionally found with a grayish tinge to the fur. 



The serotine is of particular interest as having the widest distribution of any 

 known bat, and being the only representative of the order Chiroptera which is com- 

 mon to the eastern and western hemispheres. Seeing that bats are, from their 

 power of flight, able to traverse with ease long distances over sea, it seems at first 

 sight very remarkable that the serotine is the only species which has succeeded in 

 crossing from the Old World to the New. It is, however, probable that most of 

 these animals are unable to withstand the cold of the regions about Behring Strait, 

 where the passage between the two hemispheres is the shortest, and have hence 

 failed to spread themselves in the same manner as purely terrestrial Mammals like 

 the reindeer, elk, and glutton. 



The range of the serotine extends from England to Siberia, and from Northern 

 Germany to Northern Africa, whence it is continued through Arabia and Asia 

 Minor to the valleys of the Himalayas. In Africa, it is found as far south as the 

 Gabun district on the west coast, and it probably extends to the Camerun moun- 

 tains. In America, where it was at one time regarded as distinct from the European 

 species, it appears to be widely spread from L,ake Winnipeg in the north to the 

 Isthmus of Darien, and is met with throughout all the West Indies. The serotine 

 from the Gabun constitutes a distinct variety, distinguished by the fur of the under 

 parts being of a pale yellowish white, and thus forming a marked contrast with the 

 dark brown fur of the back. 



The serotine, which is a comparatively rare and local species in England, is said 

 to have very similar habits to the noctule, so far as regards the length of its period 

 of hibernation, and its consequent late appearance in the spring are concerned. It 

 is nearly always found alone, and has a characteristically slow fluttering flight ; 



