CHAPTER III.
SUB-ORDER II.—MICROCHIROPTERA, OR INSECTIVOROUS BATS.
HORSESHOE BATS AND MEGADERMS.
[INSECTIVOROUS BATS]—Mr. Dobson’s Objection to the Name—Characteristics—Nasal Appendages—[THE VESPERTILIONINE AND EMBALLONURINE ALLIANCES]—The Fur in the two Alliances—[THE HORSESHOE BATS]—General Characteristics—Distribution—Diet—Carnivorous Propensities—[GREATER HORSESHOE BAT]—General Appearance—“Nose Leaves”—Habitat—[THE LESSER HORSESHOE BAT]—Habitat—[THE MOURNING HORSESHOE BAT]—[THE AUSTRALIAN HORSESHOE BAT]—[THE ORANGE BAT]—[PHYLLORHINÆ]—[THE DIADEM BAT]—Character of their “Nose Leaves”—Captain Hutton’s Account of their Habits—[THE PERSIAN TRIDENT BAT]—[THE MEGADERMS]—[THE LYRE BAT]—Characteristics—Called Vampire by Europeans in India—Mr. Blyth’s Account of a Megaderm’s Blood-thirstiness—[THE CORDATE LEAF BAT]—[THE AFRICAN MEGADERM]—[THE DESERT BAT]
THE second sub-order of Bats—which includes a much larger number of species, displaying a far greater variety of characters than those which have hitherto occupied our attention—has received the name of Insectivora, from the general nature of the diet of the animals composing it. Mr. Dobson objects to this name, chiefly on account of there being already an order of Mammalia bearing the same designation; and he proposes to call these Bats Microchiroptera, in allusion to the small size of most of the species in comparison with the majority of the Pteropidæ. Moreover, although the food of most of these Bats consists exclusively of insects, some of them feed, at least partially, upon other vertebrate animals, and a few are known to eat fruit.
The Bats belonging to this second sub-order may be at once distinguished by the structure of their molar teeth, which are armed with acute tubercles, separated, more or less completely, by transverse furrows. The ears also differ from those of the Pteropidæ, in that the two margins of the conch start from different points on the surface of the head, and, in a great number of cases, they are complicated by a membranous lobe, springing from near their base, or by a great development of the tragus, or anterior lobe of the ear. The tail in these Bats is generally well developed, and the index finger is never terminated by a claw.
A considerable number of Insectivorous Bats of different families have their noses furnished (we cannot say adorned) with curious leaf-like appendages, often of most complicated construction (see some of the illustrations), and these organs, as has already been stated, probably assist materially in the exercise of that delicate sense of touch which supplements or takes the place of the power of vision in guiding the Bats in their obscure abodes. In general, the presence or absence of nasal appendages being an exceedingly obvious character, has been adopted by zoologists as the means of classifying these Bats, and the order has been commonly divided into two groups—the Istiophora, or those with a nose-leaf, and the Gymnorhina, or Anistiophora, in which there is no such appendage. Mr. Dobson, who has devoted a great deal of attention to the Chiroptera, finds, however, that by following this system certain forms are grouped together which have little in common, whilst in other cases real affinities are lost sight of, and he suggests another mode of division, which, for many reasons, appears to be the most natural that has hitherto been proposed. He ranges the families of his Microchiroptera in two alliances, the leading characters of which may be briefly indicated as follows:—
HAIRS OF BATS,
MAGNIFIED.
(From Dobson’s “Monograph
of Asiatic Bats.”)
In the first, or Vespertilionine alliance, so called from its including our common Bats (Vespertiliones), the tail is generally long, never absent, and always entirely enclosed in the interfemoral membrane, with the exception of the extreme tip, which projects a very little; the pre-maxillary bones are rudimentary, and the upper incisor teeth which they carry small and weak; and the first phalanx of the middle finger is extended in repose in a line with the metacarpal bone.
In the second, or Emballonurine alliance, so called from one of the genera included in it, the tail, which is frequently absent or short, except in two or three species, is not contained within the interfemoral membrane, but has its extremity free, usually perforating the membrane and appearing on its upper surface. The pre-maxillary bones are generally well developed, and the incisors large; and the first phalanx of the middle finger is folded forward in repose above or below the metacarpal bone.
The character derived from the condition of the middle finger in repose seems to be regarded as of the most importance by Mr. Dobson, who says that it is connected with differences in the habits of the animals; but those of the tail and incisor teeth will be most useful to the student in determining to which alliance he is to refer his specimens; and, although they are liable to exceptions in the second group, will never both fail in the same individual.