Encyclopaedia Britannica, 11th Edition, "Chicago, University of" to "Chiton" / Volume 6, Slice 2

by Various

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 as the forearm. The dentition is i. 2/1, c. 1/1, p. 2/3, m. 2/2, while the index finger has no claw, and the wings arise from the spine. Eonycteris, with the dentition i. 2/2, c. 1/1, p. 3/3, m. 2/3, is also represented by a single species, E. spelaea, from Tenasserim, Burma, and the Malay Peninsula and Islands, which has somewhat the appearance of a Roussettus, but the absence of a claw in the index finger and the presence of the characteristic tongue and teeth at once distinguish it. Carponycteris (Macroglossus) and Melonycteris, the former with several and the latter with a single species, are closely allied Indo-Malay and Papuan genera, the index finger in both having a claw, but the number of the teeth being the same as in Eonycteris. C. minimus is the smallest known species of the suborder, much smaller than the serotine bat of Europe, with the fore-arm scarcely longer than that of the long-eared bat. It is nearly as common in certain parts of Burma as Cynopterus marginatus, and extends eastwards through the Malay Archipelago as far as New Ireland, where it is associated with Melonycteris melanops, distinguished by its larger size and the total absence of the tail. An allied small Carpopycteris inhabits India. Trygenycteris (Megaloglossus) woermanni, of West Africa, is the only member of the group occurring west of the Himalaya. Callinycteris of Celebes, with the dentition i. 2/2, c. 1/1, p. 2/2, m. 3/3, has a short tail and no index-claws, while Nesonycteris of the Solomons, with the dentition i. 2/1, c. 1/1, p. 3/3, m. 3/3, differs by the absence of the tail.

Microchiroptera.

The second and larger suborder, the Microchiroptera, includes all the insectivorous species, the majority of which are of relatively small size as compared with the Megachiroptera. In these bats, with a few specialized exceptions, the crowns of the Insect-eating bats. cheek-teeth are surmounted by sharp cusps, divided by transverse grooves. In the skull the bony palate narrows abruptly and is not continued backwards laterally behind the last molar; there is one rudimentary phalange (rarely two or none) in the index finger, which is never terminated by a claw; the outer and inner sides of the ear commence interiorly from separate points of origin; the tail, when present, is contained in the interfemoral membrane, or appears on its upper surface; the stomach, except in the blood-sucking group, is simple; and the spigelian lobe of the liver large, and the caudate generally small.

The bats included in this suborder are so numerous in genera (to say nothing of species) that only some of the more important types can be mentioned.

Brief references have already been made to the manner in which in many or most of these bats the tail aids in the capture of prey. From the observations of C. Oldham, it appears that these bats, when walking, carry the tail downwards and forwards, so that the membrane connecting this organ with the hind-legs forms a kind of pouch or bag. If a large insect be encountered the bat seizes it with a snatch, and slightly spreading its folded wings and pressing them on the ground in order to steady itself, brings its feet forwards so as to increase the capacity of the tail-pouch, into which, by bending its neck and thrusting its head beneath the body, it pushes the insect. Although the latter, especially if large, will often struggle violently, when once in the pouch it but rarely escapes, from which it is subsequently extracted and devoured. It is assumed that the same method of capture is employed when on the wing; and a naturalist who has observed the long-eared bat picking moths off willows states that the bat always hovers when taking off the moth, and bends up the tail so as to form a receptacle for the insect as it drops.

Fig. 6.—Head of Mitred Horseshoe Bat (Rhinolophus mitratus). From Dobson.

In the Rhinolophidae, Horse-shoe and Leaf-nosed bats of the Old World, the nose-leaf is developed and surrounds the nasal apertures, which are situated in a depression on the upper surface of the muzzle so as to look upwards; the ears are large and generally separate, without trace of a tragus or earlet; the premaxillae are rudimentary, suspended from the nasal cartilages, and support a single pair of small incisors; the molars have acute W-shaped cusps; the skull is large, and the nasal bones which support the nose-leaf much expanded vertically and laterally. In females a pair of teat-like appendages are found in front of the pubis; and the long tail extends to the margin of the interfemoral membrane. The middle finger has two phalanges, but the index is rudimentary. The fibula is rudimentary.

The Rhinolophidae are the most highly organized of insectivorous bats, in which the osseous and cutaneous systems reach the fullest development. Compared with theirs, the bones of the extremities and the wings of other bats appear coarsely formed, and their teeth seem less perfectly fitted to crush the hard bodies of insects. The complicated nasal appendages reach their highest development, and the differences in their form afford characters in the discrimination of the species, which resemble one another closely in dentition and the colour of the fur.

Fig. 7.—Head of Squirrel Leaf-Bat (Phyllorhina calcarata). From Dobson.

In the first subfamily, Rhinolophinae, the first toe has two, and the other toes three phalanges each; and the ilio-pectineal spine is not connected by bone with the antero-inferior surface of the ilium. In the horseshoe bats, Rhinolophus, the dentition is i. 1/2, c. 1/1, p. 2/3, m. 3/8, the nose-leaf has a central process behind and between the nasal orifices, with the posterior extremity lanceolate, and the antitragus large. Among the numerous forms R. luctus is the largest, and inhabits elevated hill-tracts in India and Malaysia; R. hipposiderus of Europe, extending into south England and Ireland, is one of the smallest; and R. ferrum-equinum represents the average size of the species, which are mainly distinguished from one another by the form of the nose-leaf. The last-named species extends from England to Japan, and southward to the Cape of Good Hope, but is represented by a number of local races. When sleeping, the horseshoe bats, at least in some instances, suspend themselves head downwards, with the wings wrapped round the body after the manner of fruit bats. The posture of ordinary bats is quite different, and while the lesser horseshoe (R. hipposiderus) alights from the air in an inverted position, other bats, on first coming to rest, do so with the head upwards, and then reverse their position.