TYPICAL GROUP. 
27? 
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 (F. 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. I 11 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 2b 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. 
Serotine. 
