brevicauda, both in form and dentition. Its long brush-tipped tongue (which it possesses in common with other species of the group) is used to lick out the pulpy contents of fruits having hard rinds. The food of the species of this group appears to consist of both fruit and insects, and the long tongue may be used for extracting the latter from the deep corollas of flowers. Other genera are Lonchophylla, Rhithronycteris, Hylonycteris and Lychonycteris, each with a single species (in 1904).
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Fig. 12.—Head of Long-tongued Vampire (Choeronycteris mexicana), |
The third group, Stenodermateae, presents the following characteristics:—Muzzle very short and generally broad in front, the distance between the eyes nearly always exceeding (rarely equalling) the distance from the eye to the extremity of the muzzle; nose-leaf short, horseshoe-shaped in front, lanceolate behind (except in Brachyphylla and Centurio); interfemoral membrane concave behind; tail none; inner margin of the lips fringed with conical papillae; i. 22 or 21, p. 22, m. 33 or 23 or 22; cheek-teeth broad (except in Sturnira), molars with concave or flat crowns margined externally by raised cutting-edges. Although the Stenodermateae are generally easily distinguished from the Vampyreae by the shortness and breadth of the muzzle and the form of the cheek-teeth, certain species of the latter resemble the former in external appearance, agreeing almost absolutely in the form of the nose-leaf, the ears and the tragus, and the warts on the chin. These resemblances show that, while the form of the teeth and jaws has become modified to suit the food, the external characters have remained much the same, and indicate the common origin of the two sections. The food of these bats appears to be wholly or in great part fruit. The species are divided into some eleven genera, mostly distinguished by the form of the skull and teeth. Artibeus includes the frugivorous A. perspicillatus. Stenoderma achradophilum, found in Jamaica and Cuba, with the last, from which it is scarcely distinguishable externally except by its much smaller size, differs in the absence of the horizontal plate of the premaxillae on the palate. Sturnira lilium, while agreeing with these in the form of the nose-leaf and ears, differs from all the species of the family in its longitudinally-grooved molars, which resemble those of the Pteropodidae more closely than those of any other bats; and the presence of tufts of long differently-coloured hairs over glands in the sides of the neck is another character in common with that group. Centurio senex (fig. 13) is the type of a small genus distinguished from Stenoderma and other genera of this group by the absence of a distinct nose-leaf. Some naturalists make this genus the type of a distinct subgroup, Centurioneae. Up to 1904 the genera, exclusive of Centurio, included in the Stenodermateae were Artibeus (with several sub-genera), Vampyrops (also with subgenera), Mesophylla, Chiroderma, Stenoderma (with 3 subgenera), Ectophylla, Ametrida (with 2 sub-genera), Pygoderma, Sturnira and Brachyphylla.
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Fig. 13.—Head of Masked Vampire (Centurio senex). |
The third subfamily, Desmodontieae, is represented only by the blood-sucking bats, and distinguished by having i. 12, of which the upper pair are cutting, the rudimentary molars, the very short interfemoral membrane, and the blood-sucking habit. They are further characterized as follows: Muzzle short and conical; nose-leaf distinct; p. 23, m. 11 or 00; upper incisors occupying the whole space between the canines; premolars narrow, with sharp-edged longitudinal crowns; molars rudimentary or absent; stomach elongated, and intestiniform. There are two genera, Desmodus, without calcar or molars, and Diphylla, with a short calcar and a single rudimentary molar on each side—restricted to Central and South America. Desmodus rufus, the commoner species, is a little larger than the noctule bat, and abundant in certain parts of South America, where it is troublesome owing to its attacks upon domestic animals, sucking their blood and leaving them weakened from repeated bleedings. (See Vampire.)
The fourth family of bats, unlike any of the three previous ones, has a cosmopolitan distribution. These free-tailed bats, as they are conveniently called, constituting the family Emballonuridae, present the following distinctive features. TheFree-tailed bats. nostrils are of normal form and without a nose-leaf. The premaxillae have their palatal portion imperfectly developed, and united by a slender process with the maxillae. The ears are large, with a small tragus. The middle finger has two phalanges, and the index generally a single one. The fibula is incomplete. The tail is generally short, and always partly free from the interfemoral membrane. There is generally only a single pair of upper incisors, separated by gaps from the canines, and from one another in the middle line.
The distinctive feature of these bats is the free tail-tip, which pierces the interfemoral membrane to appear on its upper surface, and may project beyond its margin. As a rule, these bats may also be recognized by the peculiar form of the muzzle, which is obliquely truncated, the nostrils projecting more or less in front beyond the lower lip, by the first phalange of the middle finger being folded in repose forwards on the upper surface of the metacarpal bone, and by the upper incisors. Although cosmopolitan, these bats rarely extend north or south of the thirtieth parallels of latitude.
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Fig. 14.—Ear of Emballonura raffrayana. |
The family may be divided into two subfamilies, of which the Emballonurinae is characterized by the incomplete premaxillae, the presence of only one phalange in the index finger, and the short tail. The dental formula is generally i. 13 (sometimes 23 or 12), c. 11, p. 23, m. 33. This subfamily may be further subdivided into subgroups or sections of which the first, Embalionurae, is characterized by the slender tail perforating the interfemoral membrane, so as to appear on its upper surface; the legs long, with a slender fibula; the incisors weak; and the premolars 22. The typical genus Emballonura presents the following features: i. 23, extremity of the muzzle more or less produced beyond the lower lip, forehead flat. The genus contains several species, inhabiting islands from Madagascar through the Malay Archipelago and Siam to the Navigator Islands. Coleura, with i. 13, the extremity of the muzzle broad, and the forehead concave, has two species from East Africa and the Seychelles. Rhynchonycteris is distinguished from Coleura by the produced extremity of the muzzle. The single species, R. naso, from Central and South America, is common in the vicinity of streams, where it is usually found during the day resting on the vertical faces of rocks, or on trunks of trees growing over water; it escapes notice owing to the greyish colour of the fur of the body and of small tufts on the antebrachial membrane counterfeiting the weathered surfaces of rocks and bark. As evening approaches it appears on the wing, flying close to the water. Saccopteryx has i. 13 and the antibrachial membrane with a pouch opening on its upper surface; it contains several species from Central and South America. This sac is developed only in the male and in the female is rudimentary. In adult males a valvular longitudinal opening occupies the upper surface of the membrane leading into a small pouch, the interior of which is lined with a glandular membrane secreting an unctuous reddish substance with a strong ammoniacal odour. Allied genera are the tropical American Peropteryx and the Brazilian Cormura. The various species of tomb-bats (Taphozous) inhabit the tropical and subtropical parts of all the eastern hemisphere except Polynesia, and are distinguished by the cartilaginous premaxillaries, the deciduous pair of upper incisors, and the presence of only two pairs of lower incisors. Most of the species have a glandular sac (fig. 15) between the angles of the lower jaw, more developed in males than in females, in some species absent in the latter. An open throat-sac is wanting in T. melanopogon, but about its position are the openings of small pores, the secretion from which probably causes the hairs to grow long, forming the black beard found in many males. The three tropical American white bats, Diclidurus, with i. 13, c. 11, p. 32, m. 33, resemble Taphozous in the form of the head and ears, but, besides other characters, differ from all other bats in possessing a pouch, opening off the centre of the interior surface of the interfemoral membrane; the extremity of the tail enters this, and perforates its base.
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Fig. 15.—Heads of Tomb-Bat (Taphozous longimanus), showing relative |
The second subfamily of the Emballonuridae, Rhinopomatinae, is represented only by the genus Rhinopoma, with several species ranging from Egypt through Arabia to India, Burma and Sumatra. The premaxillae (fig. 16) are complete; the index finger has two phalanges; the tail is very long and mouselike; and the dental formula i. 12, c. 11, p. 12, m. 23. Dr G. E. Dobson has remarked that these mouse-tailed bats might be elevated to the rank of a family, for it is difficult to determine their affinities, a kind of cross relationship attaching them to the Nycteridae on the one hand and to the Emballonuridae on the other. These bats, distinguished from all other Microchiroptera by the presence of two phalanges in the index finger
