Sub-Order 2. Microchiroptera

The members of this sub-order are mostly insectivorous though occasionally "frugivorous or sanguivorous" Bats. The molars are multicuspid with sharp cusps. The palate is not continued back behind the last molar. The second finger has but one phalanx, or none; occasionally there are two. It has no claw. The ear has its two sides separate from their point of origin upon the head. The group is of Old-World distribution.

Fam. 1. Rhinolophidae.—The Bats of this family possess the leafy outgrowths around the nostrils. The ears are large, but have no tragus. The index finger has no phalanx at all. The premaxillary bones are quite rudimentary, and are suspended from the nasal cartilages. In addition to the pectoral mammae they have two teat-like processes situated abdominally. The tail is long, and extends to the end of the interfemoral membrane.

The genus Rhinolophus has a large nose leaf, and an antitragus to the ear. The first toe has two joints, the remaining toes have three joints each. The dentition is I 1/2 C 1/1 Pm 2/3 M 3/3. There are nearly thirty species of the genus, which are restricted to the Old World. Two species occur in this country, viz. R. ferrum equinum, the Great Horse-shoe Bat, and the Lesser Horse-shoe Bat, R. hipposiderus. The name is of course derived from the shape of the nose leaf.

The genus Hipposiderus and some allied forms are placed away from Rhinolophus and its immediate allies in a sub-family Hipposiderinae. The type genus Hipposiderus, or, as it ought apparently to be called, Phyllorhina, is Old World in range, like all the other members of the family.

The nose leaf is complicated, and there are only two phalanges in all the toes; there is no antitragus to the ear. A curious feature in the osteology of the genus, and indeed of the sub-family, is the fact that the ileo-pectineal process is connected with the ilium by a bony bridge; this arrangement is unique among mammals.

The genus Anthops, only known from the Solomon Islands, and represented there by but a single species (A. ornatus), has an extraordinarily complicated nose leaf. The tail, like that of the Oriental Coelops, likewise represented by a single species (C. frithii), is rudimentary.

Triaenops, Ethiopian and Malagasy, has, like the Australian Rhinonycteris, a well-developed tail. Triaenops has also a highly-complicated nose leaf.

Fam. 2. Nycteridae.—This family is to be distinguished from the Rhinolophidae by the fact that the ear has a small tragus, and by the small and cartilaginous premaxillae. In addition to these two characters it may be added that the nose leaf is well developed, but is not so complicated as in the last family. The type genus Nycteris is Ethiopian and Oriental, nine species being African, and only one, N. javanica, being, as the specific name denotes, from the East. Megaderma is to be distinguished by the loss of the upper incisors. There is no tail, and the ears are particularly large. They are carnivorous Bats, and M. lyra, called the "Indian Vampire Bat," chiefly affects frogs as an article of diet.

Fam. 3. Vespertilionidae.—This family has not the nose leaf of other families. The apertures of the nostrils are simple, round, or crescentic apertures. The ear has a tragus, and the tail is not produced to any great degree behind the interfemoral membrane. There are two phalanges to the index digit.

This family in numbers of species is vastly in excess of any other family of Bats. The most recent estimate, that of P. L. and W. L. Sclater, allows 190. But the generic types are by no means so numerous as in the Phyllostomatidae. This is a significant fact when we reflect upon the geographical range of the two families. The Vespertilionidae range over the whole earth, while the Phyllostomatidae are practically limited to the South American continent, only just getting into the Nearctic region. They inhabit, therefore, a more restricted area, and, in consequence of competition, have specialised more freely than the widely-spread and therefore not crowded Vespertilionidae.

The genus Vesperugo is by far the largest genus of this family, embracing no less than seventy species. The tail is shorter than the head and body together; the ears are separate, and moderate or short in size; the tragus is generally short and obtuse. The dentition is I 2, C 1, Pm 2 or 1, M 3. It is a remarkable fact that this genus, unlike most Bats, produces two young at a time. The genus is universal in range, and one species, the Serotine Bat, known in this country, even ranges from the New World to the Old; but with so small a creature the possibility of accidental transportation by man must not be left out of sight. The British species are—V. serotinus, the Serotine already mentioned; V. discolor, a single example only of which has occurred, and may have been introduced; V. noctula, the habits of which were described by Gilbert White; V. leisleri; and the Pipistrelle, V. pipistrellus, which is the best-known member of the genus in this country.

The genus Vespertilio contains some forty-five species, and is world-wide in range. It has one more premolar in the upper jaw than has Vesperugo. There are no less than six British species, of which V. murinus is the largest species of Bat recorded from this country, but is not quite certainly indigenous.

Plecotus has very long ears. The dentition is I 2/3 C 1/1 Pm 2/3 M 3/3. The tragus is very large. There are but two or possibly three species, of which one is North American, and the other is the Long-eared Bat, P. auritus, of this country, but ranging as far as India. The shrill voice, inaudible to some ears, of this Bat has been heard of by everybody.

Synotus includes the British Barbastelle, S. barbastellus, as well as an Eastern form. It differs from the last genus principally by the loss of a lower premolar. The ears, too, are not so large. Otonycteris, Nyctophilus, and Antrozous are allied genera; the last is Californian, the others Old-World forms.

Kerivoula (or Cerivoula) has a long, pointed, narrow tragus. The tail is as long as or longer than the head and body. The dentition is as in Vespertilio; but the upper incisors are parallel instead of divergent as in that genus. The brilliantly-coloured K. picta is, on account of this very fact, the best-known species. The name Kerivoula, a corruption of the Cinghalese "Kehel vulha," signifies plantain bat. This Bat has been described as looking, when disturbed in the daytime, more like a huge butterfly than a Bat, which is naturally associated with sombre hues. Other species occur in the Oriental, Australian, and Ethiopian regions.

Miniopterus has a premolar less in the upper jaw; it has a long tail as in the last genus. One species, M. scheibersi, has almost the widest range of any Bat, it being found from South Europe to Africa, Asia, Madagascar, and Australia.

Natalus is an allied form from Tropical America and the West Indies. It is chiefly to be separated from Kerivoula by the short tragus to the ear.

Thyroptera is also South American. It is distinguished by the curious sucker-like discs upon the thumb and foot. These "resemble in miniature the sucking cups of cuttle-fishes." The Madagascar genus, Myxopoda, with but one species, has also an adhesive but horse-shoe-shaped pad upon the thumb and foot.

Scotophilus has shortish ears with a tapering tragus. The tail is shorter than the head and body, and is nearly contained within the interfemoral membrane. The dentition is I 1/3 C 1/1 Pm 1/2 M 3/3, with another upper incisor in the young. It is African, Asiatic, and Australian.

This genus appears to be connected with Vesperugo by Mr. Dobson's proposed genus, or sub-genus as it is generally held to be, Scotozous. The genus Nycticejus, founded for the inclusion of Scotozous dormeri, an Indian species, should, according to Dr. Blanford, replace on grounds of priority the name Scotophilus. But as this name (Nycticejus) is one introduced by Rafinesque, whose work was so uncertain and untrustworthy, it seems preferable to retain the better-known name of Scotophilus, introduced by William Elford Leach.

The genus Chalinolobus has short, broad ears with an expanded tragus. A distinct fleshy lobule projects from the lower lip on either side of the mouth. The tail is as long as the head and the body. The dental formula is I 2/3 C 1/1 Pm 2/2 or 1/2 M 3/3. The genus occurs in Africa, Australia, and New Zealand; but the African species, with diminished premolars and pale coloration, have been distinguished as Glauconycteris.

Fam. 4. Emballonuridae.—The Bats belonging to this family have no nose leaf. The tragus is present, but often very small. The ears in this family are often united. There are two phalanges in the middle finger. The tail is partly free, either perforating the interfemoral membrane and appearing upon its upper surface, or prolonged beyond its end. The face is obliquely truncated in front, the nostrils appearing beyond the lower lip.

Emballonura is Australian, Oriental, and Mascarene in range. The ears arise separately, and there is a fairly developed and narrow tragus. The tail perforates the interfemoral membrane. The dental formula is I 2/3 C 1/1 Pm 2/2 M 3/3.

Rhinopoma has the ears united; the incisors are reduced by one on each side of each jaw, and the premolars are similarly reduced, but only in the upper jaw.

Noctilio is an American genus of two or three species, which has one pair of markedly large upper incisors, which completely conceal the outer pair. On these grounds this Bat was removed from its allies and placed by Linnaeus among the Rodents, an instance of the disadvantage of the artificial scheme of classification. The species named N. leporinus has been shown to feed upon fish.

Furia, Amorphochilus, Rhynchonycteris, Saccopteryx, Cormura, and Diclidurus are other Neotropical genera of the same family.

The genus Taphozous has a tail which perforates the interfemoral membrane, appearing on its upper surface; it is capable of being withdrawn. The premaxillaries are cartilaginous. The dentition is I 1/2 C 1/1 Pm 2/2 M 3/3. The upper incisors often disappear. Many species of the genus have a gular sac, opening anteriorly between the jaws. This is better developed in the males. The genus ranges from Africa through Asia to New Guinea and Australia. There are some twelve species.

The genus Molossus has short legs and well-developed fibulae. The tail is thick and fleshy, and is prolonged far beyond the margin of the interfemoral membrane. The ears are united together above the nose; the tragus is minute. The dentition is I 1/1 or 1/2 C 1/1 Pm 1/2 or 2/2 M 3/3. This genus, which is confined to the tropical and subtropical portions of America, has long and narrow wings. The Bats can thus fly rapidly, twist about with ease, and capture strongly-flying insects. There are a large number of species.

Nyctinomus is an allied genus, and also has many species. These range through both hemispheres. The chief differences from Molossus are that the premaxillary bones are separate in front or united by cartilage, and that the incisors may be three in the lower jaw.

Fam. 5. Phyllostomatidae.—The Bats of this family are extremely numerous and almost entirely confined to South America. None of them occur outside the New World. There are some thirty-five genera. The members of the family are to be distinguished by the presence of the nose leaf, by the well-developed premaxillae, and by the possession of three phalanges by the middle finger. They are large, and the tragus of the ear is well developed.

Vampyrus of South America contains the large species V. spectrum, which, mainly on account as it seems of its "forbidding aspect," was supposed to be a bloodsucker. This genus has two incisors on each side of the upper jaw.

The genus Glossophaga represents another type of structure in this family. The tongue is long and extensile, and is much attenuated towards the tip, where it is covered with strong and recurved papillae. This structure was at one time thought to indicate a bloodsucking habit; but its use appears to be merely that of scooping out the soft insides of fruits, upon which the Bat mainly lives. The incisors are only one on each side of the upper jaw. The really bloodsucking Bats of this family belong to the genera Desmodus and Diphylla. The former is the Vampire, the species being known as Desmodus rufus. These Bats have no tail; there is no true molar tooth; the canines are large, and the single pair of upper incisors quite caniniform, and very sharp and strong. These are the main teeth for aggression. In accordance with its diet of blood, the Vampire has a peculiarly modified intestine. The gullet is provided with a bore so small that nothing but fluid food could pass down it; the stomach is intestiniform in shape.