ON NOCTURNAL ANIMALS. 325 
woodcut—be attentively observed when exposed to the strong 
glare of sunlight, that hazy, lustreless expression so indicative of 
night habit is readily appreciated. 
Hearing in these animals is a well-developed sense. Not only 
is the internal ear a highly efficient organ, but, as is well known 
in several of the Bat families, the enormous size of the thin 
membranous conch is out of all proportion to the dimensions 
of the animals themselves. Moreover, the tragus, especially in 
the Nycteride and Vespertilionide, is extraordinarily exaggerated. 
The external nasal apparatus, even in our English Horse-shoe 
Bat (Rhinolophus), is an extremely absurd-looking nose-leaf ; 
but in the Vampires (Phyllostomide) and Megaderms the same 
part, in size, complexity, and ugliness, almost exceeds the 
ridiculous. Smell, in fact, like hearing, has a superadded 
intensity, through the exterior apparatus and its wonderful 
tactile power. ‘I'aste, in the Fruit Bats, at least, is in no way 
deficient, though probably little influencing nocturnal pecu- 
liarities. Concerning touch, it is the strangest physiological 
problem in the whole history of their economy. The wing 
membrane of a Bat, most persons are aware, is a thin tegumentary 
extension stretched between the enormously lengthened but 
attenuated bones of the hand (see figure)—that is, both palm and 
fingers. At one bend, that which represents the wrist-joint, is a 
short-clawed grappling-hook, the thumb. The lower and upper 
arm bones are each greatly elongated, especially the former. 
This long-levered arm, which otherwise would be weak and 
futilely beat the air when outspread, is further strengthened and 
improved as an organ of flight by a delicate though tough web 
running out like a guy-rope in front. Furthermore, a continuation 
of broad web reaches from the inner finger and arm to the body, 
and onwards to the heel. ‘The form of the tail varies in different 
genera, and is capable of being extended according to the length 
of the membrane by which it is attached tu the sides of the leg. 
Throughout all this extent of membrane highly elastic tissue and 
minute muscular fibres are so distributed that the web can be 
partially or wholly furled as circumstances require. 
The young cling to the mother by clutching her most 
tenaciously, and she flies about or roosts head downwards, 
enveloping her offspring with the wing-membranes. But the 
wing- and leg-webs, the great membranous ears, and, indeed, 
