INTRODUCTION. ix which in Megaderma (as in Pteropodide) is perforated by a foramen (Plate X. fig. 3a; Plate XI. fig. 2); in the Emballonuride postorbital processes are scarcely developed in any of the genera except in those included in the group Emballonure, where, in most of the species, they are very long, and almost circumscribe the orbit. In Megachiroptera, however, long postorbital processes, haying their bases traversed by a foramen, are well developed in nearly all the species; in the genus Pteropus, which includes the largest species of the order, they reach their highest development, and in several of the species there are corresponding processes from the zygomatic arches ; but in Péeropus lewcopterus alone is the orbital ring complete (seo p. 32 and Plate IV. fig. 1).
The nasal bones vary considerably in length and form. In the Megachiroptera they reach their greatest length, extending so far in front that the nasal opening is small and directed forwards (Plate IV. fig. 1). In Microchiroptera (except in the group G'lossophage) the nasals are generally short, especially in the leaf-nosed species of the Vespertilionine alliance, where the nostrils open on the upper surface of the muzzle; in the Rhinolophide they are raised in a vertical direction, supporting the highly developed foliaceous cutaneous appendages constituting the “ nose-leaf”’; in the Phyllostomide their form varies most considerably—in Vampyri and Glossophage long and narrow, in Stenodermata short and broad, or deficient, as in Chiroderma, where a deep fissure extends backwards between the orbits (Plate X XIX. fig. 3), or much elevated, increasing the thickness of the muzzle in front, as in Pygoderma (Plate XXVIIL. fig. 4). The greatest difference exists in the form and size of the premaxillary bones, in some cases even in those of species belonging to the same genus. In Pteropodide they are slender, but generally united in the centre; in Rhinolophide they are quite rudimentary, consisting of small osseous lamine projecting forwards from the nasal cartilages ; in Wycteride they are cartilaginous in Megaderma and small in Nycteris; in all the genera of Vespertilioncd@ they consist of slender ununited bones supported by the upper maxillaries, and separated by a wide space in front (Plate XIII. figs. 2a, 3; Plate XIV. figs. 36,46; Plate XV. figs.55,66). In those genera of Emballonuride which approach the Vespertilionide nearest in general structure, the premaxillary bones are also very feebly developed, and in one genus (Laphozous) they are cartilaginous, as in Megaderma ; nevertheless they are less widely separated in front, and in this respect lead towards the more perfectly developed premaxille of such
x INTRODUCTION, genera as Noctilio, Cheiromeles, Molossus, and Mystacina, in which they are deeply united together, as in the allied family Phyllostomide. In all the genera of the latter family (except Monophyllus, Ischnoglossa, Phyllonycteris, Lonchoglossa, and Glossonycteris, of the group Glossophage) the premaxillaries are well developed and united in the centre (Plate XXIV. figs. 2, 6), reaching their culminating point in the sanguiyorous group Desmodontes, where they support a pair of enormous trenchant incisors (Plate XXX. fig. 76). Zygomatic arches are well developed in Pteropodide (Plate IV. fig. 1) and Rhinolophide ; in the latter family they reach their greatest size in Triwnops*; in Emballonuride and Phyllostomide they are slender, and in several genera of the latter family (Carolla, Phyllonycteris, Glossonycteris, and Cheronycteris) wanting. The depth of the sagittal and occipital crests varies much in different species, even in those of the same genus, and evidently depends chiefly on the size of the muscles of mastication, which have their origin from the sides of the skull, the development of these muscles again depending on the nature of the food of the animal with which the form and size of the teeth are correlated. Thus in Desmodus rufus, which lives on the blood of animals, and in which the grinding-teeth are rudimentary, the crown of the skull is quite smooth, without trace of either occipital or sagittal crests. In the Megachiroptera the bony palate is broad behind, produced behind the last molars, and gradually narrowing backwards (PlatelV. fig. 6); in Microchiroptera it is abruptly narrowed in a line with the last molars, and produced backwards, forming the floor of the posterior nares (Plate XIV. fig. 5a, Plate XXIV. fig. 3) ; or in some genera of Phyllostomide (Stenoderma, Pygoderma, Ametrida) the horizontal plates of the palate-bones are partially or wholly deficient, and the palate is deeply cut as far forwards, in some species, as a line drawn between the first upper molars (Plate XXVIII. figs. 2-4). The two species included in the group Furie have been placed in separate genera, chiefly on account of the different development of the horizontal plate of the palate-bones, although otherwise very closely allied (see pp. 356, 357), so that it is doubtful how far this difference in structure can be regarded as a generic character. The auditory bulle ossee vary considerably in the different species in size, which appears to be correlated with that of the external ear, though exceptions to this rule are not wanting, as, for instance, * See my paper “On Osteology of Trienops persicus,” and plate, referred to above, footnote, p. vil.
INTRODUCTION. x1 in Chalinolobus (Plate XIV. fig. 5a) and Miniopterus, where, although the ear-conch is small, the bulla ossew are remarkably large. The tympanic is thin-walled and very loosely connected with the surrounding bones, and does not develop an external canal; the spiral turns of the cochle are generally distinctly visible externally through the very thin walls of the capsule, and in some species number as many as four. In the Rhinolophide the auditory bulle ossece attain their greatest size (especially in the genus Rhinolophus, where they nearly meet in the middle line, the intervening basioccipital bone being reduced to a narrow isthmus); and it is noteworthy that in these Bats the tragus is not developed *. Paroccipital processes are present in most of the genera; they reach their greatest development in Megachiroptera, where they are rather long and narrow; in Microchiroptera they are comparatively much smaller, especially in the family Vespertilionida. The shoulder-girdle varies very slightly in the different families, having the same office to fill in all. The clavicle is always very strong, long, and curved; the scapula large, oval-triangular in outline ; the postscapular fossa greatly exceeds the anterior fossa, and is deeply concave for the origin of the large muscles arising therefrom ; the spine of the scapula is well developed, with a large acromion ; the coracoid is long and curved.
The humerus is long, but compared with the radius is scarcely two thirds its length; the form of its upper extremity varies very slightly ; the external and internal tuberosities are prominent, the internal being the larger ; the pectoral ridge is enormously developed for the insertion of the great pectoral muscle, and the inner side of its base is marked by the groove for the deltoid tendon; the shaft of the humerus is smooth and cylindrical; the distal extremity has, in all species, a large entocondyloid tuberosity, which, in some species (especially in the species of Rhinolophide) is very large, in the genus Y'ricnops developing a long styloid process}; the articular surface is marked by a deep sigmoid notch; there is no anconeal fossa nor supracondylar foramen. The ulna is rudimentary; its proximal extremity, which articulates with but a small part of the humerus posteriorly and externally, is anchylosed with the radius ; immediately beyond the joint it is reduced to a very slender splintlike bone more or less curved backwards and separated from the * See remarks on the tragus, infra, p. xix.
t See plate vi. figs. 4, 4, Journ. Asiat. Soc. Beng. pt. ii. (1872), referred to above, in footnote, p. vil.
xi INTRODUCTION.
radius, with which it coalesces about the middle. In all species a detached sesamoid bone exists in the tendon of the triceps muscle, and is generally found in skeletons. The radius forms, with the humerus, almost the whole elbow-joint; it is very long, in some species (Phyllorhina commersonii and Ph. tricuspidata, e. g.) a8 long as the head and body.
The proximal row of the carpus consists of a single bone (the united scaphoid, lunar, and cuneiform bones), which, with the extremity of the radius, forms the radiocarpal joint: in the distal row the trapezium, trapezoid, and os magnum vary much in size in the different families ; the unciform appears to be the most constant, and the pisiform is generally very small. But the chief differences in the bones of the carpus and their articulations are observable between those of the Megachiroptera, in which the thumb and second finger are so well developed, the latter generally with a distinct claw, and the Microchiroptera, in which the same digits are comparatively much smaller, and the second finger has a single rudimeutary phalanx only* unprovided with a claw. In the Megachiroptera the trapezium is by far the largest bone in the distal row; its inner surface is deeply grooved for articulation with the trochlear extremity of the metacarpal bone of the thumb; its distal extremity fills up the space between the base of the metacarpal bones of the thumb and first finger, with which it articulates, while its proximal end forms a rounded head, which is received into a deep depression between the united scaphoid and lunar bones. The trapezoid is very small and quadrate above, articulating with the outer portion only of the second metacarpal bone; the os magnum is next in size to the trapezoid, and the unciform is but slightly smaller than it; the pisiform is very small, with a circular upper extremity. In the Microchiroptera, even in the frugivorous species of Phyllostomide, the trapezium is much smaller than either the os magnum or unciform, and does not much exceed the trapezoid in size, while its articulation with the concave extremity of the metacarpal bone of the thumb is very simple, and its proximal extremity is not received into a deep concavity in the scapho-lunar bone; the trapezoid has a long wedge-shaped distal process, which, with the end of the trapezium, is received into the space between the extremities of the first and second metacarpal bones, the latter almost wholly articulating with it; the unciform is as large as the os magnum, and the pisi- * With the single exception of Rhinopoma, in which the index finger has two small phalanges (vide infra, p. xiii.)
INTRODUCTION. xiii form is much larger than in Megachiroptera. On the dorsal aspect of the wrist, in Phyllostoma hastatum, there are three well-developed sesamoid bones—one on the radial side, protecting the radiocarpal joint internally, another covers the metacarpo-carpal joint of the thumb, while the third and largest overlies the articulation of the os magnum with the second and third metacarpal bones. The manus is, in all the species, composed of five digits. The first, fourth, and fifth respectively consist of a metacarpal bone and two phalanges; in the second and third the number of phalanges is different in certain families.
The first finger (or thumb) always terminates in a claw, which, with the proximal phalanx, is most developed in Megachiroptera* and in the frugivorous species of Phyllostomide. The second finger reaches its highest development in Megachiroptera, consisting of a metacarpal bone and three phalanges, the terminal phalanx being provided with a claw (except in Honycteris, Notopteris, and Cephalotes). In these three genera (which include only a single species each) the third phalanx is short but quite distinct, and is included in the wing-membrane. In nearly all the species of Microchiroptera, on the other hand, there is asingle rudimentary phalanx only in the second finger; and in Rhinopoma microphyllum alone are two phalanges found. The presence, therefore, of three phalanges in the middle finger is characteristic of the Megachiropterat. In the Rhinolophide there is no distinct phalanx in the second finger; a slight thickening like a joint terminates the osseous portion of the metacarpal bone, but I have not been able to distinguish a true articular surface. In the Nycteride, Vespertilionide (except Thyroptera), and Phyllostomide there is a short but generally distinct phalanx ; in Thyroptera (in other respects also a most anomalous genus, vide infra, p. xiv) the second finger is represented by a rudimentary metacarpal bone only. In the Emballonuride, especially in the genera in which the first phalanx of the third finger is folded (in repose) forward upon the upper surface of the metacarpal bone, the second finger is formed by the metacarpal alone; in Woctilio (which so * The species of this Suborder, when feeding, grasp the fruit between the claws of the thumb and second finger. These fingers are, to a certain extent, opposable in these Bats, and this is evidently rendered possible by the different form and mode of articulation of the trapezium and trapezoid bones, compared with the same parts in Microchiroptera.
+ This character has been accidentally omitted from my definitions of the Suborders at p. 2.
xiv INTRODUCTION.
closely approaches the Phyllostomide through Chilonycteris) there is a very imperfect joint, with a slender bony phalanx about 0-15 inch long, and in Rhinopoma (as above remarked) there are two distinct phalanges. In the very remarkable genus Calops (Rhinolophide) alone is the metacarpal bone of this finger longer than thatof the third. The third or middle finger is by far the longest, and, except in the Phyllostomide, has two phalanges, as in the fourth and fifth fingers. In the Phyllostomide, and in the anomalous genera Thyroptera and Mystacina, there is a third phalanx, which evidently corresponds to the cartilaginous extremity of the second phalanx in the other families of Microchiroptera; for in some of the larger species of Molossi there is an imperfect joint terminating the osseous portion of the second phalanx of this finger, and in Molossus perotis (the largest of that group) I have observed a distinct joint dividing this bone into two. Compared with the fifth finger, this finger reaches its greatest length in the Hmballonuride and Phyllostomide. In the genera Taphozous and Diclidurus, and in the group Molossi, the metacarpal bone equals or slightly exceeds the whole length of the fifth finger. The metacarpal bone of the third finger is generally longer than that of the fifth ; but in the genera Pteropus and Rhinolophus, in the Nycteride, and in many of the genera of Phyllostomide it is shorter than it.
While the metacarpal bones of the fourth and fifth fingers are generally but slightly shorter, and in some cases exceed in length that of the third finger, the phalanges of the same fingers vary greatly in length in different families and in different species of the same family. In Megachiroptera, as in the case of the other fingers also, they reach their highest development, and equal, or even slightly exceed, the proximal phalanx in length. In Microchiroptera they are well developed in Rhinolophide and in Nycteride, considerably shorter in proportion to the length of the metacarpals in Phyllostomide, and least developed in Hmballonuride, especially in the group Molossi and in the genera Taphozous and Diclidurus. In these genera the terminal phalanx of the third finger is very short and its distal third cartilaginous. As the antero-posterior diameter of the wing depends on the length of the fourth and fifth fingers, and its lateral extent on the third finger, this family is characterized by the length and narrowness of the wings, which confers on the individuals of each species the power of exceedingly rapid flight, contrasting remarkably with the comparatively slow oar-like motion of the broad wings of the species of Pteropodide.
INTRODUCTION. xv In the genus 7’rienops alone a very peculiar short bony process projects from the outer side of the proximal extremity of the terminal phalanx of the fourth finger. (See p. 124, and plate in Journ. Asiat. Soc. Bengal, referred to in footnote above.) As might be expected from their aerial mode of locomotion, the pelvic girdle of Chiroptera is very weak. The iliac bones are long and narrow. In most species the pubic bones of opposite sides are very loosely united in front in males, in females they are widely separated; in the Rhinolophide alone do these bones form a symphysis. The eminentia ileo-pectinea develops in all species a long pectineal process ; in the subfamily Phyllorhinine alone this process is united with a similar one proceeding backwards from the anterior extremity of the ilium, bridging the space between, and forming a large preacetabular foramen, larger than the obturator foramen which is placed posterior and slightly inferior to it. (See plate vi. figs. 7,8, 14, in Journ. Asiat. Soc. Bengal, referred to above.) This form of the pelvis (first described and figured by the writer) appears to be unique among mammals, and occurs in no other known species of Bats.
The acetabulum is small and directed outwards and slightly upwards,and with this is related the peculiar position of the leg, which is rotated outwards and upwards, so that when the animal is resting on the ground the knee is directed upwards as in a grasshopper. In striking contrast with the great development of the anterior extremities, the posterior limbs are small and generally weak, the combined length of the femur, tibia, and foot rarely equalling that of the forearm alone. The femur is, like the humerus, slender and cylindrical, with a small head and very short neck ; the trochanters are prominent and nearly equal in size ; its form differs very slightly throughout the species. The bones of the leg and foot are more variable. In the subfamily Molossine alone, in which the legs are short and strong, is there a well-developed fibula. In all other species this bone is either very slender or cartilaginous and ligamentous in its upper third, or reduced to a small bony process above the heel, as in Megaderma, or altogether absent, as in Nycteris.
The foot consists of a very short tarsus, and of long, slender, laterally compressed toes, with much-curved claws; the os calcis terminates (in nearly all the species) in a long cartilaginous process, the caleanewm, which acts as a support to the posterior margin of the interfemoral membrane, and is most developed in those species
Xvi INTRODUCTION.
in which the interfemoral is very large and the tail rudimentary or perforating the membrane and appearing upon its upper surface, as in most of the genera of Emballonuride, and in the groups Mormopes and Vampyri of Phyllostomide.
The first toe is composed of a metacarpal bone, a proximal and an ungual phalanx, and is slightly shorter than the other four toes, which have each an additional phalanx, except in the subfamily Phyllorhinine and in the anomalous genus Thyroptera, where all the toes have the same number of phalanges as the first toe and are equal to it in length. In the very remarkable genus Cheiromeles the first toe is thumb-like and separated from the others; in the Molossi the first and fifth toes are much thicker than-the intermediate toes.
Moscutar Sysrrm.
Few striking differences are observable in the muscular system of the Chiroptera. As Dr. Macalister remarks, “a strong family likeness pervades the entire series; the differences are chiefly slight, though often suggestive, varieties of detail”*. As the few differences known are of little importance in their bearing on the systematic arrangement of the species, it will be sufficient here to refer to the principal work on the subject, of which the title is given in the footnote below.
Nervous System.
Witnout entering upon a general description of the nervous system in Chiroptera, I purpose, under this head, to consider the chief modifications in the organs of touch and hearing which have so important relations to the systematic arrangement of the species, and which probably reach the highest development among Mammals in this Order.
In the Rhinolophide, Nyctertde, and Phyllostomide peculiar foliaceous cutaneous expansions surround or extend backwards behind the nasal apertures (see Plates VI., XI., XXX.). In no other species of Mammals have analogous structures been found, and their functions and homologies appear to be imperfectly understood. A careful investigation of the structure, relative position, mode of origin, and nervous supply of these processes leads me to believe that they are delicate organs of an exalted sense of touch, analogous to * “The Myology of the Chiroptera.” By Alexander Macalister, M.B., &c. Phil. Trans. Roy. Soc. 1872, pp. 125-171, plates 13-16.