INTRODUCTION. XXV left lateral lobes. In Cynonycteris the right central lobe is much larger than the left; the gall-bladder lies in the left lateral fissure ; the caudate lobe is not quarter the size of that in Cynopterus, and extends upon scarcely one third of the inner surface of the kidneys. In Harpyia, which externally appears most nearly related to Cynopterus, the liver differs remarkably from that of all other genera of Megachiroptera in the slight depth of its fissures: the right and left lateral fissures do not extend halfway to the attached margin, and but slightly exceed in depth the remarkably large notch between the free margins of the central lobes ; the gall-bladder is contained in a concavity in the walls of the right lateral fissure, and its extremity is visible in the centre of the fissure on the convex surface of the liver; the caudate lobe is represented by a ridge-like prominence, and the right lateral lobe is considerably larger than the left, its posterior inferior free margin forming a triangular acutely pointed projection. In Epomophorus (E£. monstrosus and E. macrocephalus) the central lobes are not divided by a notch behind, the caudate lobe is short and obtuse, and the gall-bladder lies on the concave surface of the right central lobe. In Honycteris the right central lobe much exceeds the left, and the gall-bladder is lodged in a cavity in its outer side which enters the right lateral fissure; the caudate lobe is represented by a ridge only; the right lateral lobe is very large, with a deep concavity which contains half the kidney. In Notopteris (which presents such a very remarkable form of stomach) the liver on the whole resembles that of Eonycteris, but the gallbladder hangs back freely.
The form of the liver is generally more uniform in the different species of Microchiroptera. It will therefore be sufficient to describe it in one or two characteristic genera in each family. In Phyllorhina commersoni the left lateral lobe is equal to half the whole organ in size; the left central lobe is very small, and bounded behind and to the right by the right central, to the left by the left lateral; the large gall-bladder is contained in a hollow space between the adjacent edges of the central and left lateral lobes ; the Spigelian lobe is distinct, free, and quadrate, but not large; caudate lobe very short. In Mycteris the Spigelian lobe is very long and tongue-shaped, filling up the space between the cesophagus and the pyloric extremity of the stomach. In Nyctophilus the Spigelian lobe is also well developed and similar in shape ; the caudate lobe very short; the gall-bladder lies between the right central and the right lateral lobes. In Minzopterus the liver is very
XXV1 INTRODUCTION, deeply divided, and the posterior and right margin of the right central lobe is produced backwards as a long attenuated process ; the Spigelian lobe is rather small and pointed, the caudate extends nearly to the middle of the kidney. In Vesperugo the Spigelian lobe is very large and leaf-like. In Taphozous nudiventris the left lateral lobe is also very large, the Spigelian lobe of remarkable size, and the caudate lobe is moderately developed. In Rhynchonycteris and in Emballonura the general form of the liver is similar to that of Taphozous, the Spigelian lobe also very large, but the caudate is indistinct. In MJolossus the liver is generally similar to that of the preceding genera, but the caudate lobe is better defined. In the Phyllostomide the general form of the liver does not differ much from that of the Hmballonuride, except in the sanguivorous group Desmodontes, in which, as first pointed out by Prof. Flower, it differs not only from that of the other Bats, but also from that ‘of all Insectivora and Carnivora in being comparatively little divided into lobes. The umbilical fissure is distinct, but the lateral fissures are only notches in the free edge of the organ, imperfectly marking off two small and nearly equal central lobes. The left lateral lobe is large and crescentic, the right thick and rounded ; but neither the Spigelian nor the caudate lobes are distinct, being only indicated by a strong ridge on the under surface of the right lateral lobe” *.
In Carollia the left lateral lobe is larger than half the whole organ, and its concave right margin is much overlapped by the left central; the gall-bladder lies in a hollow on the right side of the right central lobe ; the Spigelian lobe is well developed and tongueshaped ; the caudate very short. In the truly frugivorous genus Artibeus the Spigelian lobe is remarkably small, and the caudate indistinct.
Curanrous System.
In extent, peculiar modifications, and sensitiveness the Cutaneous System reaches its highest development in this Order. Asa sensory organ its chief modifications in connection with the external ear, and with the nasal and labial appendages, have been described under the head of Nervous System. It remains therefore to consider its relative development as an organ of flight, and the position and form of the peculiar glandular structures into which it enters. The extent and shape of the volar membranes depend mainly on the form of the bones of the anterior extremities, and on the pre- * Medical Times and Gazette, 1872, ii. p. 60.
INTRODUCTION. XXVii sence or absence of the tail. Certain modifications of these membranes, however, are met with which evidently do not depend upon the skeleton, but are related to the habits of the animals, and to the manuer in which the wing is folded in repose.
The volar membranes consist of :—(1) the “ antebrachial membrane,” which extends from the point of the shoulder along the humerus and more or less of the forearm to the base of the thumb, the metacarpal bone of which is partially or wholly included in it ; (2) the ‘‘ wing-membrane,” which is spread out between the greatly elongated fingers, and extends along the sides 0? the body to the posterior extremities, generally reaching to the feet; and (3) the ‘“‘ interfemoral membrane,” the most variable of all, which is supported between the extremity of the body, the legs, and the calcanea. (Vide Plates I., VI., XIII.)
The antebrachial and wing-membranes reach their highest development in those species which are fitted only for aerial locomotion, and which when at rest hang head downwards suspended by the claws of the hind feet, with the body enveloped in the wings. We find these membranes therefore well developed in the Pteropodide, in Nycteride especially, in most species of the Vespertilionide, and in nearly all the Phyllostomidee except the group Desmodontes. In Emballonuride, especially in the subfamily Molossine (the species of which are, of all Bats, the most fitted for terrestrial progression), the antebrachial membrane is reduced to the smallest size, and is not developed along the forearm, leaving also the thumb quite free, and the wing-membrane is very narrow and folded in repose completely under the forearm (see pp. 403, 444).
Owing to the peculiar manner in which the wing is folded in nearly all the species of Emballonuride, the margin of the membrane between the fourth and fifth fingers is deeply concave, and does not extend to the end of the terminal phalanx of the fifth finger. In all species of Megachiroptera the wing-membrane extends to the backs of the feet, in some species to the backs of the first phalanges of the toes ; whereas in Microchiroptera (with the exception of the genera Vampyrus and Lophostoma) it is attached to the sides of the legs or feet, rarely to the bases of the calcanea. In most species this membrane has its origin from the sides of the body more or less removed from the spine; but in Wotopteris and Cephalotes, and in the single species Chilonycteris (Pteronotus) davyt, it arises from the centre line of the back, to which it is connected by a short and very slender longitudinal membranous process ; and while the
XXVill INTRODUCTION.
back beneath is well covered with fur, the overlying wing-membrane is naked. In Pteropus melanopogon and its allies, and in Vespertilio macrotarsus and V. pilosus, the membranes arise near the spine. The development of the interfemoral membrane is evidently related to the nature of the food, as it reaches its greatest size in the insectivorous, but in nearly all the frugivorous and sanguivorous species is deeply cut out behind, or forms a narrow projection along the legs. Thus it is well developed in the families Rhinolophide, Nycteride, Vespertilionide, Emballonuride (except in Rhinopoma, believed to be partially if not wholly frugivorous), and in the insectivorous species of Phyllostomide ; while in the frugivorous and sanguivorous species of the same family, and in the Megachiroptera, it is very small or rudimentary.
In the insectivorous species it appears not only to aid their rapid doubling motions when in pursuit of their insect prey by acting as a rudder on the air (see p. 403), but also to assist them in the capture and retention of the larger insects, such as the smooth-bodied Coleoptera, as it becomes, when pressed forwards by the tail upon the abdomen, a very effective trap. Its small size in the frugivorous and sanguivorous species which do not require it, to which, indeed, its presence would be actually injurious as impeding their motions when searching for food when suspended by their feet, is easily understood, (See remarks on the interfemoral membrane of Molossi at p. 403, and on that of one of the frugivorous species of Phyllostomide at p. 503.) Odoriferous glands and pouches opening on the surface of the outer skin are developed in many species, but in most cases more so in males than in females, and so constitute very remarkable secondary sexual characters. They are chiefly found in the highly organized forms, as in the larger species of Megachiroptera, in the subfamily Phyllorhinine (Rhinolophide), inthe groups Vampyri and Stenodermata (Phyllostomide), and in the family Emballonuride. They may be classed as :— 1. Frontal pouches (Phyllorhina, p. 127, Pl. IX. fig. 8). 2. Gular glands and pouches (Taphozous, p. 378; Cheiromeles, p. 405, Pl. XXI.; Molossus, p. 410, Pls. XXI., XXII. ; Phyllostoma, p. 484).
3. Shoulder-pouches and glands (Zpomophorus, p. 5, Pl. IT. fig. 3 ; Pteropus, p. 16; Cynonycteris, p. 74).
4. Thoracic glands (Ametrida, p. 531, Pl. XXX. fig. 2). 5. Pubic and anal glands and follicles (Rhinolophide, p. 99 ; Megaderma, p. 154; Noctilio, p. 393; Eonycteris, p. 95).
INTRODUCTION. XXIX 6. Wing-pouches (Saccopteryx, p. 369).
The form and relative development of these structures in male and female will be found described under the head of each species in which they occur.
Among the Microchiroptera the odoriferous secretions of these glandular organs appear to act principally in bringing the sexes together in the dark retreats in which they hide, as they are always found most abundant during the rutting-season ; but in the large Species of Megachiroptera, as in Pteropus, which roost in trees exposed to the attacks of passing enemies, and in which they are also developed in the female, but to a less extent, the strong musky odour exhaled, and which fills the air in the neighbourhood of their haunts, is evidently protective. (See also my paper “ On Secondary Sexual Characters in Chiroptera,” P. Z. 8. 1873, pp. 241-252.) GENERATIVE ORGANS.
The penis is pendulous in all Bats, and in many species provided with a well-developed bone. Its form varies sometimes considerably even in species of the same genus. Thus in Rhinolophus luctus the glans penis is very large and cylindrical, and the urethra opens on the upper surface at a distance of more than 0:2 inch from its distal extremity, to which it extends forwards in an open groove; in most other species of the genus the urethra opens at or near the extremity of the glans; also in Vesperugo, in the species of the subgenus Hesperoptenus the form of the penis (described at p. 241) is quite different from that of other species of the genus. In Vesperugo noctula and in Scotophilus pallidus there is a long and slender bone. In WNoctilio the glans is long and conical, and the urethra opens on its upper surface about 0:1 inch behind the conical extremity, the orifice guarded above by a small fleshy process, from which a groove runs backwards to the point of attachment of the prepuce. In most species of Microchiroptera the prepuce projects considerably beyond the glans, and its great development in Vesperugo abramus is characteristic of that species (see p. 227). In Megachiroptera, with few exceptions, the species have a broad spatulate bone in the glans penis. This is especially well developed in the genus Pteropus, in which it appears to form the greater part of the glans. In Honycteris, although the glans seems fleshy, there is a broad bone concealed within, and the opening of the urethra is triangular. In Harpyia the penis bone is slender, more like that in some of the Microchiroptera.
XXX INTRODUCTION.
In all species of Chiroptera the testes pass periodically into a temporary scrotum formed out of the skin of the perineum (see Plate XIII. fig. 1).
The preputium clitoridis is long in the species of the Emballonurine alliance, and appears to reach the greatest development in Noctilio (see p. 393), in which it is nearly as long as the penis of the males. In the species also included in this alliance the opening of the vulve is longitudinal; whereas in the Vespertilionine alliance and in the Megachiroptera the vulve open transversely, and the preputium clitoridis is short. In Cheiromeles torquatus and in Noctilio leporinus the clitoris is perforated by the urethra. The form of the uterus varies considerably in different genera, and even in different species of the same genus. In Megachiroptera the uterus is deeply divided into two cornua, which extend almost to the os uteri. Externally the body of the uterus appears to be nearly as long as the cornua; but this is due to the union of the adjoining sides of the cornua forming a common septum.
In Microchiroptera the cornua are very long in many species— Megaderma spasma and Phyllorhina speoris, e.g., where the uterus externally resembles that of the Megachiroptera; but I have not found the internal septum carrying the cornua almost to the os uteri as described above, and the body of the uterus is much longer. In other species (Scotophilus temminckii, Miniopterus schreibersii, Taphozous nudiventris, and Molossus abrasus, e. g.), the body of the uterus is still longer, almost as long as the cornua. In Corinorhinus macrotis the uterus is club-shaped, with two broad and short horns ; while in the far-remoyved species Vesperugo serotinus and Artibeus planirostris the uteri agree in their simple and undivided condition. GEOGRAPHICAL D1sTRIBUTION.
Although most abundant in the tropics and in the warmer parts of the temperate zones of both Hemispheres, representatives of the order are to be found in every region where flying insects abound, extending even to the confines of the Arctic Circle. No Bats have been found in Iceland, in St. Helena, in the Galapagos Archipelago*, or in Kerguelen Land, nor do they appear to inhabit any of * Jn reply to my inquiries Mr. Darwin has very kindly given me the following information :—“ With respect to Bats at the Galapagos, I would assuredly have recorded their presence had any been seen. Of course it does not follow from this that there are none; yet, as I never collected in any place with so few insects, it is probable the Bats are really absent.”
INTRODUCTION. XXXI the islands of the Low Archipelago, But they are present in most other oceanic islands of any extent; few of the islands of the Pacific west of the Low Archipelago are without some species of the frugivorous Pteropodide, even the small Savage Island, south-east of the Navigators’ group, being inhabited by Pteropus keraudrenii. Of the six families into which the Chiroptera are divided, two only (the Vespertilionide and Emballonuride) extend into both the Eastern and Western Hemispheres ; and even of these the species of the latter family inhabiting America are quite distinct from those of the Old World, and the genera nearly so, Nyctinomus alone being common to both; while of the sixteen genera of Vespertilionide, two only (Vespertilio and Vesperugo) are generally distributed, and one species alone (Vesperugo serotinus) is certainly known to inhabit both the Old World and America *.
It is worthy of note that, of the single genus of Emballonuride which is common to both Hemispheres, four species only out of twenty-one inhabit America, and these are all closely related to one another, and very far removed from any of the Old-World species. Of the remaining families, the Pteropodide, Rhinolophide, and Nycteride are strictly limited to the Old World, the Phyllostonide to America.
The Eastern and Western Hemispheres are therefore, on the whole, eminently distinct in their Chiropterous fauna; and it will be found, when we come to examine the distribution of the genera of each family, that each zoological region has its characteristic species also.
The Pteropodide are distributed throughout the Ethiopian, Oriental, and Australian Regions (except Tasmania and New Zealand); but of the genera one only, Cynonycteris, extends throughout all these Regions. Zpomophorus is strictly limited to that part of the Ethiopian Region included within the continent of Africa. Cynopterus is almost limited to the Oriental Region, a single anomalous species, C. latidens (which differs widely from all the other species in the form of its teeth), being found in the Moluccas. Honycteris is, as yet, known from the Indo-Malayan Subregion alone; Macroglossus has the only species of this family * This fact has not been previously noticed. It has hitherto been generally understood among zoologists that the American species of Bats were totally distinct from those of the Old World. It is probable that Vesperugo abramus and V. borealis also extend into America (see remarks on the distribution of these species, infra, pp. 193, 208, 229).
XXXil INTRODUCTION.
common to both the Oriental and Australian Regions ; Notopteris appears to be limited to the Polynesian Subregion; Harpyia and Cephalotes are characteristic of the Austro-Malayan Subregion. The distribution of the genus Pteropus (which includes more than half the whole number of the species of Pteropodide) is more remarkable than that of any of the other genera of Chiroptera, and is comparable only to that of the Lemurs. The Comoro Islands in the Mozambique Channel form its westward limit, thence the species extend throughout the Malagasy Subregion, even to the small hurricane-swept island of Rodriguez, and northwards through the Amirantes and Seychelle Islands to India, where their westward limit is found at the southern frontier of Baluchistan (see p. 52); from India they extend eastwards throughout the Oriental and Australian Regions (except Tasmania and New Zealand), inhabiting Polynesia as far eastwards as Samoa and Savage Island (see p. 16). Although 1000 miles of unbroken ocean divide the Seychelle Islands from the Chagos group (the nearest intermediate land to India), the Indian and Madagascar species (Pteropus medius and Pt. edwardsit) are very closely allied; while, on the other hand, not a single species crosses the narrow channel between the Great Comoro Island and the African coast.
The Ehinolophide are limited to the tropical and warmer parts of the temperate zones of the Eastern Hemisphere from Ireland to Japan, from South Africa to New Ireland and Australia. No species has as yet been recorded with certainty from any part of the Polynesian Subregion, from Tasmania, or from New Zealand. With the exception of Rhinolophus ferrum-equinum, which extends throughout the Ethiopian and warmer parts of the Palearctic Regions, the species of this family inhabiting each of the zoological regions comprised within the area of its distribution are distinct and characteristic. No species of the subfamily Phyllorhinine extends into the Palearctic Region; Celops is limited to the Oriental Region, and Rhinonycteris to the Australian: these last two genera, however, include but a single species each. The very remarkable forms Phyllorhina commersonii and Ph. cyclops belong to the Ethiopian Region, but the former species alone extends also into the Malagasy Subregion.
The Nycteride are limited to the Ethiopian and Oriental Regions, one species only passing slightly beyond the limits of the latter Region (see p. 158), and none have as yet been found in the Malagasy Subregion of the former. The Ethiopian species of the