Nearly all the Vampyreae appear to be insectivorous, so that the term cannot be considered indicative of habits; but a few, if not all, probably supplement their insect diet with fruit. Vampyrus spectrum (the largest bat in the New World) is said to be wholly frugivorous, and Otopterus waterhousei appears to prey occasionally on smaller bats. The genera may be arranged in two subgroups according as the tail is produced to the margin of the interfemoral membrane or perforates it to appear on its upper surface. In the first division are included three genera, Lonchorhina, Otopterus (or Macrotus) and Dolichophyllum (or Macrophyllum), the first represented by L. aurita, characterized by an extraordinary long nose-leaf, and peculiarly large ears and tragus. In the second subsection are included Vampyrus, Chrotopterus, Tonatia (Lophostoma) Micronycteris, Glyphonycteris, Trachyops, Phylloderma, Phyllostoma, Anthorhina (Tylostoma), Mimon, Hemiderma (Carollia) and Rhinophylla; all, with the exception of the last, distinguished chiefly by the form of the skull and the presence or absence of the second lower premolar. Phyllostoma hastatum, next in point of size to Vampyrus spectrum, is a well-known species in South America; P. elongatum (fig. 11) differs in its smaller size and larger nose-leaf. Hemiderma brevicauda, a small species, closely resembles Glossophaga soricina, and forms a connecting link between this and the next group. Rhinophylla pumilio is the smallest species of the family; further distinguished by the absence of a tail, the narrowness of its molars, which do not form W-shaped cusps, and the small size of the last upper molar, characters connecting it and the group with the Stenodermateae. Both in Hemiderma and Rhinophylla the zygomatic arch is incomplete.
| Fig. 11.—Head of Lesser Javelin Vampire (Phyllostoma elongatura). |
The next subsection, Glossophageae, presents the following distinctive features: Muzzle long and narrow; tongue long and extensible, attenuated towards the tip, and beset with long filiform recurved papillae; lower lip with a wide groove above, and in front margined by small warts; nose-leaf small; tail short or none; i. 2/2, p. 2/3 or 3/3 or 2/2, m. 3/3 or 2/3 or 2/2; teeth narrow; molars with narrow W-shaped cusps, sometimes indistinct or absent; lower incisors small or deciduous. The species included in this group represent some ten genera, distinguished principally by differences in the form and number of the teeth, and the presence or absence of the zygomatic, arch of the skull. In Glossophaga and Phyllonycteris the upper incisors form a continuous row between the canines. In Monophyllus and Leptonycteris (Ischnoglossa) they are separated into pairs by a narrow interval in front; while in Lonchoglossa, Glossonycteris and Choeronycteris they are widely separated and placed in pairs near the canines. In the first four of these genera the lower incisors are present (at least to a certain age), in the last three they are deciduous even in youth. The zygomatic arch is wanting in Phyllonycteris, Glossonycteris and Choeronycteris. The typical species is Glossophaga soricina, which, as already mentioned, closely resembles Hemiderma 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).
| Fig. 12.—Head of Long-tongued Vampire (Choeronycteris mexicana), showing brush-tipped tongue. From Dobson. |
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. 2/2 or 2/1, p. 2/2, m. 3/3 or 2/3 or 2/2; 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.
| Fig. 13.—Head of Masked Vampire (Centurio senex). From Dobson. |
The third subfamily, Desmodontieae, is represented only by the blood-sucking bats, and distinguished by having i. ½, 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. 2/3, m. 1/1 or 0/0; 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. The Free-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.
| Fig. 14.—Ear of Emballonura raffrayana. From Dobson. |