A striking confirmation of the naturalness of this arrangement is to be found in the fact that even the microscopic character of the fur differs in the two alliances. In the first, the longer hairs of the fur when magnified show a series of scales, imbricated or partly overlapping each other, something like the grains of corn in the ear, the tips, which are not acute or very prominent, forming a sort of spiral line round the surface of the hair (see [Fig. a]). In the second alliance, on the contrary, the scales—which are smaller and narrowed, with acute and projecting tips—are arranged in rings round the hair, giving it a somewhat jointed appearance (see [Fig. b]). Mr. Dobson has examined the fur of a majority of the genera of these Bats, and also submitted his specimens to the examination of Dr. J. D. Macdonald, F.R.S., and both these gentlemen find the differences in the structure of the hair always perfectly in accordance with the arrangement above indicated, with but two exceptions, one of them being a genus which really forms a sort of connecting link between the two alliances, and the other having fur quite different from that of any other Bat, and in which the scales can hardly be distinguished.
VESPERTILIONINE ALLIANCE.
FAMILY II.—RHINOLOPHIDÆ, OR HORSESHOE BATS.
The Bats of this family are usually called Horseshoe Bats, from the circumstance that their noses are furnished with leaf-like membranous appendages of rather complicated structure, the front part of which is usually something like a horseshoe in its form (see [figure on next page]). The nostrils are situated within this horseshoe, between it and the other parts of the nose-leaf, which vary considerably in their shape and structure. The middle finger has two phalanges, or joints, beyond the long metacarpal bone, a character common to all the Bats of this alliance, with only a single exception; and the ears have no tragus. Throughout the family there are two small incisor teeth in the upper jaw, and four in the lower, and three true molars on each side in both jaws; but the number of pre-molars varies, being usually two on each side in the upper jaw, and either two or three in the lower; whilst in one curious species the upper pre-molars are only one on each side.
HEAD OF THE GREATER HORSESHOE BAT.
The Rhinolophidæ are confined to the Eastern hemisphere, of which they chiefly inhabit the warmer parts. They are generally insectivorous in their habits, but some of the larger species are said to prey upon other vertebrate animals, and not even to spare their smaller brethren. Thus, Mr. Frith informed Mr. Blyth that “a number of these Bats were in the habit of resorting to the verandah of his residence in Mymensing (Burmah), and that every morning the ground under them was strewed with the hind-quarters of Frogs and the wings of large Grasshoppers and Crickets. On one occasion the remains of a small fish were observed; but Frogs appeared to constitute their chief diet—never Toads, and of a quiet evening these animals could be distinctly heard crushing the heads and smaller bones of their victims.”
Captain Hutton also states that various species of Rhinolophidæ, and some Vespertilionidæ,[164] when confined with some smaller species than themselves, will prey upon them; and he suggests that these carnivorous propensities may be “the reason why the larger species keep aloof in pairs, instead of congregating, as do some of the smaller kinds.” In illustration of this suggestion he gives the following interesting account of a cave frequented by Bats:—He says, “I know of an enormous cave at Mussooree, to which various species, both large and small, are in the habit of resorting for rest and concealment during the day. Standing within this spacious vault in the earliest hours, just before the first streaks of day appear, the spectator is perfectly astonished at the numbers of Bats resorting to it; not, however, in one promiscuous crowd, but in separate detachments, each seeking its own particular quarter of the cavern, and alighting against the sides, at first within reach of a Butterfly-net, and commence crawling upwards and backwards to spots beyond the reach of invasion from below. Here, in one spot, will be seen a pair of Rhinolophus luctus, hanging high up, and quite apart from all the rest; in another place hangs a pair of Phyllorhina armiger, the large ears and the facial crests in active tremulous motion as the head is turned in every direction to ascertain that no intruder is nigh its dwelling-place, until, this restlessness gradually passing off, the animal hangs at length quietly suspended by the feet. In another direction are a dozen or more of Rhinolophus minor, rapidly scrambling all together, like a lot of crabs, up the inequalities of the rocky surface, and hurriedly disappearing into some deep, narrow crack or crevice; while again, in another part, the same scene is observed, as dozens of a very small species of Nycticejus (Scotophilus) scramble into similar hiding-places, to rest in peace until the hour for again emerging in search of prey calls them all forth once more.”
THE GREATER HORSESHOE BAT.[165]
Although, as already stated, most of the Horseshoe Bats inhabit warm countries, several species are found in more temperate regions. One of these is the Greater Horseshoe Bat (Rhinolophus ferrum-equinum), which occurs, although not very abundantly, in various parts of the South of England. He is a puffy and rather pursy-looking little fellow, with a head which appears full large for his body. The length of his head and body is about two and a half inches, and that of his tail, which is entirely enclosed in the interfemoral membrane, about an inch and one-third. His wings have an expanse of thirteen or fourteen inches. The fur on the upper surface is reddish-grey, and on the lower surface very pale grey; the membranes are of a dingy brown colour, and the ears and nasal appendages pale brown. The ears are large, broad at their attachment to the head, pointed and turned outwards at the apex. From the outer margin ten or a dozen transverse furrows run towards the middle of the ear. The outer margin, at its junction with the head, is also continuous with a low rounded lobe[166] which bounds the aperture of the ear in front, and may be used to close the cavity. The nasal appendages, or “nose-leaves,” are very curious and complicated (see [figure, p. 281]). The anterior, or horseshoe-shaped portion, lies longitudinally upon the nose, and is formed of three concentric elevations, the innermost of which bounds the depression in which the nostrils are placed. Between the nostrils arises the central process, the anterior portion of which forms a sort of cup, behind which the process is slightly narrowed and excavated, but again widens before terminating in a short but rather sharp point. This point overhangs the third, or frontal leaf, which touches the horseshoe portion, and is about as broad as the latter at their junction, and tapers up to a point upon the forehead. The eyes, which are like little black beads, are placed on each side of the junction of the horseshoe and the frontal leaf.