TYPICAL GROUP. 277 



In White's Nidural History vf Sclborne, it is stated tliat 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 Canibridgeshii-e as late as the 

 first week in November. 

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



^**- hairy-armed bat {V. leideri). Its popular name is derived from the 



presence of a broad baud of tine short hairs on the under side of the wing-menibranc 

 running fi-om 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 inci.sor teeth. In the hairy- 

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

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

 in the noctule the former is much wider at the ba.se than the latter, while it also 

 has the crown hollowed out to receive th(^ sunnnit of the lower tusk, or canine. 

 Then, again, the lower incisor teeth in the hairj'-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 charactei-s may seem trivial and unimportant, but they are amply 

 sufiicient 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 2i 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 Qaadrupeds, " 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 n^.inutes only, and then lost 

 sight of. It appears to afi'ect 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, a2)parently uncertain where to go ; 

 generally, although not always, at a considerable elevation, and in a few minutes it 

 is gone." Like the noctule, the haiiy-armed bat has a wide geographical distribu- 

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

 recoi-ded from one locality in the Himalaya. 



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



Serotine. ... . . 



a group distinguished fi-om 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-pai-ts ; 



the hair being long and silky, and the wing-mendjranes dark brown, or nearly 



black. There is, however, some degree of individual variation in coloui', specimens 



being occasionally found with a greyish tinge to the fur. 



