TYPICAL GROUP. 277 



In White's Natural History of Selborne, it is stated that the noctule is not to 

 be seen on the wing before the end of April, nor later than July. Other observers 

 have, however, seen this bat in Hampshire and Sussex in August and September, 

 while one instance is on record of its appearance in Cambridgeshire as late as the 

 first week in November. 



Hairy-armed Closely allied to the noctule is the British species known as the 



Bat - hairy-armed bat (V. leisleri). Its popular name is derived from the 

 presence of a broad band of fine short hairs on the under side of the wing-membrane 

 running from the fore-arm to the wrist. Since, however, this feature is also found 

 in the noctule, it is obviously not distinctive of the species to which it gives the 

 name, and we must therefore seek for another characteristic by which to distinguish 

 the two species. Such a characteristic is found in the incisor teeth. In the hairy- 

 armed bat the outer pair of these teeth in the upper jaw are equal in cross-section 

 at the base to the inner pair, but the height of their crowns is much less ; whereas 

 in the noctule the former is much wider at the base than the latter, while it also 

 has the crown hollowed out to receive the summit of the lower tusk, or canine. 

 Then, again, the lower incisor teeth in the hairy-armed bat form a regular semi- 

 circle, with scarcely any overlapping of one over another ; whereas in the noctule 

 they have broad crowns, are set obliquely in the jaw, and largely overlap one 

 another. Such characters may seem trivial and unimportant, but they are amply 

 sufficient to prove the specific distinctness of the hairy-armed bat, which is, more- 

 over, a considerably smaller animal than the noctule, the combined length of the 

 head and body being rather less than 2J inches. Needless to say, however, these 

 two bats are often confounded together, although careful attention to the points 

 mentioned will always serve to distinguish them. Moreover, careful 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 Leisler'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." Like the noctule, the hairy-armed bat has a wide geographical distribu- 

 tion, ranging through Europe and the temperate regions of Asia, and having been 

 recorded from one locality in the Himalaya. 



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 general 

 colour of the fur is chestnut-brown above, and yellowish-grey 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 colour, specimens 

 being occasionally found with a greyish tinge to the fur. 



