Page:EB1911 - Volume 06.djvu/257

Fig. 2.—Head and Neck of Epomophorus franqueti (adult male). From Dobson. The anterior (a.ph.s) and posterior (p.ph.s) pharyngeal sacs are opened from without, the dotted lines indicating the points where they communicate with the pharynx; s, thin membranous partition in middle line between the anterior pharyngeal sacs of opposite sides; s.m, sterno-mastoid muscle separating the anterior from the posterior sac.

but in the Emballonuridae, and also in the Molossinae, which are the best fitted for terrestrial progression, the antebrachial membrane is reduced to a small size, and not developed along the fore-arm, leaving the thumb quite free, while the wing-membrane is narrow and folded in repose under the forearm. The relative development of the interfemoral membrane has been referred to in connexion with the caudal vertebrae. Its small size in the frugivorous and blood-sucking species, which do not require it, is easily understood. Scent-glands and pouches opening on the surface of the skin are developed in many species, but in most cases more so in males than in females (fig. 3). As rule, bats produce only a single offspring at a birth, which for some time is carried about by the female parent clinging to the fur of her breast; but certain North American bats commonly give birth to three or four young ones at a time, which are carried about in the same manner.

Bats are divisible into two suborders, Megachiroptera and Microchiroptera.

Fig. 3.—Frontal Sac and Nose-Leaf in Male and Female Masked Bat (Phyllorhina larvata). From Dobson.

Megachiroptera.

The first of these comprises the fruit-eating species, which are generally of large size, with the crowns of the cheek-teeth smooth and marked with a longitudinal groove. The bony palate is continued behind the last molar, narrowing slowly backwards; there are three phalanges in the index Fruit-eating bats.finger, the third phalange being terminated generally by a claw; the sides of the ear form a ring at the base; the tail, when present, is inferior to (not contained in) the interfemoral membrane; the pyloric extremity of the stomach is generally much elongated; and the spigelian lobe of the liver is ill-defined or absent, while the caudate is well developed. This group is limited to the tropical and sub-tropical parts of the Eastern Hemisphere.

 

 Fig. 4.—Head of a Flying-Fox or Fruit-Bat (Pteropus personatus).
 From Gray.

All the members of this suborder are included in the single family Pteropodidae, the first representatives of which are the African epauletted bats, forming the genus Epomophorus. In this the dental formula is i. 2/2 (or 1/2), c. 1/1, p. 2/3, m. 1/2. Tail short or absent, when present free from the interfemoral membrane; second finger with a claw; premaxillae united in front. The species are strictly limited to Africa south of the Sahara, and are distinguished by the large and long head, expansible and often folded lips, and the white tufts of hair on the margins of the ears. The males are provided with glandular pouches, situated in the skin of the side of the neck near the point of the shoulder, which are rudimentary or absent in females. In the males they are lined with glandular membrane, from which long coarse yellowish hairs project to form conspicuous epaulet-like tufts on the shoulders. The males often have a pair of air-sacs extending outwards on each side from the pharynx beneath the integument of the neck, in the position shown in fig. 2. These bats appear to live principally on figs, the juicy contents of which their voluminous lips and capacious mouths enable them to swallow without loss. The huge and ugly West African hammer-headed bat, Hypsignathus monstrosus, represents an allied genus distinguished by the absence of shoulder-pouches, and the presence of leaf-like expansions of skin on the front of the muzzle, and of distinct cusps on the outer sides of the cheek-teeth. The great majority of the bats of this group, commonly known as “flying-foxes,” are included in the typical genus Pteropus, of which the dental formula is i. 2/2, c. 1/1, p. 3/3, m. 2/3. All are of large size, and the absence of a tail, the long pointed muzzle, and the woolly fur covering the neck render their recognition easy. One of the species, P. edulis, inhabiting Java, measures 5 ft. across the fully extended wings, and is the largest member of the order.

The range of the genus extends from Madagascar through the Seychelles to India, Ceylon, Burma, the Malay Archipelago, Japan, New Guinea, Australia and Polynesia. Although two species inhabit the Comoro Islands, scarcely 200 m. from the mainland, not one is found in Africa; while the common Indian species is closely allied to the Madagascar flying-fox. The Malay Archipelago and Australia form the headquarters of these bats, which in some places occur in countless multitudes. The colonies exhale a strong musky odour, and when awake the occupants utter a loud incessant chatter. Wallace’s fruit-bat of Celebes and Macassar has been made the type of a separate genus, as Styloctenium wallacei. In Roussettus (or Cynonycteris) the dentition is as in Pteropus, but the tail is short, and the fur of the nape of the neck not different from that of the back: its distribution accords with that of Pteropus, except that it includes Africa and does not reach farther east than New Ireland. R. aegyptiacus inhabits the chambers of the Great Pyramid and other deserted buildings in Egypt, and is probably the species figured in Egyptian frescoes. Boneia, with two species, from Celebes, differs in having only two upper incisors. Harpyionycteris and Scotonycteris, respectively from the Philippines and West Africa, are represented by a single species each; but of Cynopterus, which is mainly confined to the Indo-Malay countries, there are some half-score different kinds. The dentition is i. 2/2 or 1, c. 1/1, p. 3/3, m. 3/3, the muzzle is shorter than in Roussettus, with the upper lip grooved in front as in Pteropus, while the tail and fur resemble those of the former genus. These bats are extremely voracious, a specimen of the Indian C. marginatus having eaten a banana twice its own weight in three hours. Among several Austro-Malay genera, such as Ptenochirus and Balionycteris, the tube-nosed bats of the genus Gelasinus (or Harpyia) are remarkable for the conformation of the nostrils (fig. 5). Cephalotes, with one species, ranging from Celebes to the Solomon group, has the dentition i. 1/1, c. 1/1, p. 2/3, m. 2/3, premaxillae not united in front, nostrils simple, muzzle short, index finger without a claw, tail short. As in Gelasinus, the wing-membrane arises from the middle line of the back, to which it is attached by a longitudinal thin process of skin; the wings are naked, but the back covered with hair. Leipenyx is an allied West African genus with one species.

Fig. 5.—Head of Papuan Tube-Nosed Bat (Gelasinus major). From G. E. Dobson.

The foregoing belong to the typical subfamily Pteropodinae, while the remainder represent a second group, Carponycterinae (or Macroglossinae), characterized by having the facial part of the skull produced, the molar teeth narrow, and scarcely raised above the gum, and the tongue exceedingly long, attenuated in the anterior third, and armed with long recurved papillae near the tip. The single representative of the first genus, Notopteris macdonaldi, inhabiting Fiji, New Guinea and the New Hebrides, is distinguished from other bats of this family by the length of its tail, which is nearly as long