ORDERS OF MAMMALIA. 339 
many respects, however, it might be well to regard the order as 
merely a modified branch of the /zsectivora, just as the Pizzt- 
grada are regarded as a modified offshoot of the Carnivora. 
The Chetropiera or Bats.are essentially characterised by the 
fact that the fore-limbs are much longer than the hind-limbs, 
and have several of the fingers enormously elongated. These 
enormously lengthened digits are united by an expanded leathery 
membrane or “patagium,” which not only stretches between 
the fingers, but is also extended between the fore and hind 
limbs, and is attached to the sides of the body (fig. 184). The 
patagium thus formed often includes the tail, and is nearly or 
quite naked or destitute of hairs on both sides. It is used as 
an organ of true flight, and, in accordance with this, there are 
well-developed collar-bones (clavicles), and the breast-bone is 
furnished with a ridge for the attachment of the pectoral mus- 
cles. Of the fingers of.the hand at least three are destitute of 
nails. The mammary:glands are placed upon thechest. Teeth 
of three kinds are always present, and the canines are always 
well developed. 
The Bats are all twilight-loving or nocturnal animals, and 
they are the only Mammals which possess the power of true 
flight, though several others can make extended leaps from tree 
to tree. The eyes are small, but the ears are very large, and 
their sense of touch is most acute. During the day they retire 
to caves or crevices in rocks, where they suspend themselves by 
the short thumbs, which are provided with claws. In their 
flight, though they can turn with great ease, they are by no 
means as rapid and active as the true Birds. The tail is some- 
times very short, sometimes moderately long, and is usually in- 
cluded in a continuation of the “ patagium,” which extends be- 
tween the hind-legs: The body is covered with hair, but the 
patagium is usually nearly or quite hairless. Most of the Bats 
hybernate. 
The Cheiroptera are conveniently divided into the two sec- 
tions of the Insectivorous and Frugivorous Bats. In the first 
section are all our British species, which universally live upon 
insects, In the second, or fruit-eating, section of the Chezrop- 
tera are only the Fox-bats (Ptevopid@), which are especially 
characteristic of the Pacific Archipelago, inhabiting Australia, 
Java, Sumatra, Borneo, &c., but occurring also in Asia and 
Africa. ‘They are amongst the largest of the Bats, one species 
