There are several varieties (one of them peculiar to the island) of the horse-shoe-headed Rhinolophus, with the strange leaf-like appendage erected on the extremity of the nose.
It has been suggested that the insectivorous bats, though nocturnal, are deficient in that keen vision characteristic of animals which take their prey by night.
I doubt whether this conjecture be well founded; it certainly does not apply to the Pteropus and the other frugivorous species, in which the faculty of sight is singularly clear. As regards the others, it is possible that in their peculiar æconomy some additional power may be required to act in concert with that of vision, as in insects, touch is superadded, in its most sensitive development, to that of sight. It is probable that the noseleaf, which forms an extended screen stretched behind the nostrils in some of the bats, may be intended by nature to facilitate the collection and conduction of odours, just as the vast expansion of the shell of the ear in the same family is designed to assist in the collection of sounds—and thus to supplement their vision when in pursuit of prey in the dusk by the superior sensitiveness of the organs of hearing and smell.
One tiny little bat, not much larger than the humble bee[201], and of a glossy black colour, is sometimes to be seen about Colombo. It is so familiar and gentle that it will alight on the cloth during dinner, and manifests so little alarm that it seldom makes any effort to escape before a wine glass can be inverted to secure it.
Although not strictly in order, this seems not an inappropriate place to notice one of the most curious peculiarities connected with the bats—their singular parasite, the Nycteribia.[202] On cursory observation this creature appears to have neither head, antennæ, eyes, nor mouth; and the earlier observers of its structure satisfied themselves that the place of the latter was supplied by a cylindrical sucker, which, being placed between the shoulders, the insect had no option but to turn on its back to feed. Another anomaly was thought to compensate for this apparent inconvenience;—its three pairs of legs, armed with claws, are so arranged that they seem to be equally distributed over its upper and under sides, the creature being thus enabled to use them like hands, and to grasp the strong hairs above it while extracting its nourishment.
It moves, in fact, by rolling itself rapidly along, rotating like a wheel on the extremities of its spokes, or like the clown in a pantomime, hurling himself forward on hands and feet alternately. Its celerity is so great that Colonel Montague, who was one of the first to describe it minutely[203], says its speed exceeds that of any known insect, and as its joints are so flexible as to yield in every direction (like what mechanics call a "ball and socket"), its motions are exceedingly grotesque as it tumbles through the fur of the bat.
