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Show 1873.] CHARACTERS IN THE CHIROPTERA. 251 are generally of an intensely black colour throughout; in a few specimens only, of apparently very aged individuals, the fur on the back of the head and neck has a slightly reddish tinge; while the males have the whole back of the head and nape of the neck to the shoulders bright orange or pale yellow (very rarely, in old males, reddish brown) as in Pt. medius, contrasting as remarkably with the sombre hues of the females as the brilliantly coloured skin of the male Mandrill contrasts with the same parts in the other sex. A review of the varieties of secondary sexual characters exhibited by various species of Chiroptera described in the foregoing pages shows that in almost all cases these differences depend on the possession by the male (rarely by the female) of accessory organs, generally odoriferous glands, used probably for the purpose of bringing the sexes together during the rutting-season, or for exciting the female; and this might be expected in animals in which the power of vision is almost entirely supplemented by an extraordinary development of the senses of touch and smell. Differences, depending partly or entirely on the possession by the male of fur of a much more brilliant hue, or distinguished by different markings, or by tbe greater length of certain portions, are met only, to any appreciable extent, in the Frugivorous Bats, in which the sense of sight is well developed*. The inference that will naturally be drawn from a perusal of this paper will be, not only that many species of Chiroptera possess well-marked secondary sexual characters, but also that several species exhibit as remarkable differences in this respect as any that have been observed in the whole class Mammalia. The danger of generalizing statements from imperfect data is thus strikingly illustrated ; and we are reminded of the old axiom in logic which biologists, both great and small, would do well to keep ever before their minds : - " A particulari ad universale argumenturn non est." The science of life is yet in its infancy. Man has existed for thousands, perhaps millions, of years upon the earth ; but the grand question of his origin and of that of other animals is believed by many distinguished biologists to have already been finally settled from a consideration of a few facts collected within the past half century, most of them within the past decade. specimen I received, a female with intensely black fur throughout, was sent m e by Mr. Homfray, Assistant Superintendent, Port Blair. Other specimens, male and female, were obtained by m e in M a y last near Port Blair; and Mr. Homfray has since sent m e from the Nicobars specimens of the common Flying Fox of these islands, which I find in no respect different from the Andamanese species. * The beard in the males of Taphozous melanopogon evidently depends on the presence of a subcutaneous gland, in the position occupied by the gular pouch in other species of the genus, which discharges its secretion by minute pores. The long black hairs forming the beard grow about these pores, their coarseness and length depending on the glandular secretion by which they are abnormally nourished. The length of the hair composing the epaulettes of the Epomophori is probably due to the same cause; but its remarkable difference in colour requires another explanation. |