Chapter 42

SKULL OF DESMODUS.

In general characters these Bats approach the Stenoderms. The tail is entirely deficient; the interfemoral membrane forms a mere border to the legs; the ears are of moderate size and furnished with a small tragus; and the nasal appendage consists only of the part analogous to the horseshoe in other genera, the upper leaf being absent. The thumb is very long and strong. The only species of the genusDesmodus(D. rufus) measures about four inches in length, and some fifteen or sixteen inches in expanse of wing. The fur varies considerably in colour, but generally shows various tints of brown, from a reddish-brown, as in the specimen originally described by Prince Maximilian, through a plain brown, to ashy-brown and mouse-colour, variations which have induced zoologists to describe several distinct species, now, however, generally regarded as identical. This species in its various forms seems to be very generally distributed in all the warmer parts of South America, from Chili to Guiana. As already stated, it appears to be the only species that has been detected in the act of blood-sucking; and by some of the most recent authorities it and its near ally,Diphylla ecaudata, are believed to be the only South American Bats which are really guilty of that atrocity.

Dr. Hensel, who has discussed this matter at some length, in connection with his observations on the Bats of Brazil, remarks that the teeth of most of the Phyllostomidæ are like those of the true Carnivora, and the wounds inflicted by them, as may easily be observed by the captor of one of them, are of the same kind as those produced by the teeth of a small Carnivore. In the latter, as he says, there is no loss of substance; the bite consists usually of four punctures, where the canine teeth have pierced the skin, and severe bleeding occurs only when these teeth have penetrated to some depth, and injured one or more of the larger vessels.

DESMODUS.

But the wounds observed on Horses or Mules that have been bitten by blood-sucking Bats are, as already stated, of quite a different character. They form small oval surfaces, which are but slightly sunken, the surface of the cut not being perpendicular to that of the spot bitten, as would be the case in wounds produced by long canine teeth, but in a general way parallel to it. A similar wound would be produced by lifting a small portion of skin by means of a pair of forceps, and then passing a knife along the surface of the skin, as if to shave it, but so as to cut away the raised portion. By a cut or bite of this kind, notwithstanding its being so superficial, a portion of substance is always lost, a great number of fine cutaneous vessels are cut through, and an abundant and long-continued bleeding iscaused.[250]Such wounds, says Dr. Hensel, can be produced only by large, peculiarly shovel-like, and very sharp incisor teeth, and such teeth occur only in the allied generaDesmodusandDiphylla. With the latter he had no acquaintance, but he obtainedDesmodus rufusin abundance. He says it usually lives in cavities in the rocks, but sometimes in large hollow trees. “In capturing these animals,” he adds, “I have often had the opportunity of observing the wounds that they inflicted on the noses of my Dogs which tried to seize them, or on my own hands, and found that they perfectly resembled those of the Horses bitten by the blood-suckers. The creatures bite with the rapidity of lightning, and even when they seem merely to touch the skin, a piece of it is found to be deficient. They cannot therefore hold fast with their teeth, as all other Phyllostomidæ do, for these, when they are captured, in their rage seize with their teeth any object within their reach, and hold it for some time.” It would appear, especially from the rudimentary state of their molar teeth, that these Bats cannot be supposed to prey upon insects, no remains of which have ever been found in their stomachs, and their excrements consist solely of a black, pitch-like paste, evidently digested blood. This is evacuated near the entrance of the caves in which the creatures live, and while they are waiting until the darkness outside is sufficient for them to start on their piratical excursions. The floor at such a place is found covered with a layer of the above-mentioned black mass, which may attain a thickness of a foot or more. Dr. Hensel mentions that a large Dog, after paying a visit to one of the caverns haunted by these Bats, looked as if he had got long black boots on. The same writer is of opinion that the Bats must obtain the greater part of their food by capturing and sucking the blood of the smaller warm-blooded animals. As the large domestic animals are not indigenous to America, it is probable that they only furnish an occasional meal to some of the great swarms of these Bats that infest the country.

STOMACH OF DESMODUS.STOMACH OF LONG-EARED BAT.STOMACH OF PTEROPUS.

STOMACH OF DESMODUS.

STOMACH OF LONG-EARED BAT.

STOMACH OF PTEROPUS.

That the Desmodus is specially organised for a peculiar diet is shown by the extraordinary structure of its stomach, which, as described by Professor Huxley, whose observations are confirmed by Professor Peters, differs from that of any other Mammal. The gullet (ginfigure) is exceedingly narrow, and opens into a transversely elongated tubular stomach, which passes directly on the right side into the intestine (i), the duodenum and stomach not being separated by any pyloric constriction, andlimit of the stomach in this direction being indicated solely by the insertion of the gall-ducts at a point only one-fifth of an inch from the opening of the gullet. The other, or cardiac division of the stomach, on the contrary, is enormously developed, forming an elongated and convoluted cæcum (c) several inches long, and becoming considerably wider than at its origin. In one specimen examined, the body of the Bat measured only three inches and one-fifth in length; the intestine, from the pylorus to its termination, was eleven inches long; while the above-mentioned cæcal portion, when straightened out, was six inches and a half in length, or twice as long as the body, and nearly two-thirds the length of the intestine. Professor Peters describes the cardiac cæcum in the specimen examined by him as only from one to two inches long. It may, perhaps, have belonged to a distinct species. The stomach in the Frugivorous Pteropidæ is elongated and tubular, no doubt for the reception of the huge quantity of vegetable food which they require to support their existence. In the ordinary Insectivorous Bats the organ is small and globular, with the pyloric and cardiac orifices near each other, the nourishment afforded by their usual diet being in a tolerably concentrated form and firm condition. The extraordinary cæcum of the blood-suckers, no doubt, serves as a reservoir for their fluid nutriment, in which it may be stored for a time almost unchanged, and gradually subjected to the process of digestion.

The second species of blood-sucking Bat mentioned in the earlier part of this article,Diphylla ecaudata, agrees with the Desmodus in its dentition and general characters, but is entirely destitute of interfemoral membrane, and has the lower incisors pectinate.

The following table of the classification of Bats here adopted will assist the reader in the comprehension of the information given in the preceding pages:—

SUB-ORDERI.—MEGACHIROPTERA.Family I.—PTEROPIDÆ.Group 1.—Pteropi.—Tongue moderate; molars well developed. Genera.—Pteropus, Cynopterus, Cynonycteris, Harpyia, Epomophorus, Hypsignathus, and Cephalotes.Group 2.—Macroglossi.—Tongue very long; molars very small. Genera.—Macroglossus, Eonycteris, and Notopteris.SUB-ORDERII.—MICROCHIROPTERA.A.—Vespertilionine Alliance.Family II.—RHINOLOPHIDÆ.Sub-family 1.—Rhinolophinæ.—First toe with two, remainder with three phalanges. Genus.—Rhinolophus.Sub-Family 2.—Phyllorhininæ. Toes equal, each of two phalanges. Genera.—Cœlops, Phyllorhina, Rhinonycteris, and Triænops.Family III.—NYCTERIDÆ.Sub-family 1.—Nycterinæ.—Nasal apparatus concealed; tail long. Genus.—Nycteris.Sub-family 2.—Megaderminæ.—Nose-leaf distinct; tail short. Genus.—Megaderma.Family IV.—VESPERTILIONIDÆ.Group 1.—Vespertiliones.—Crown of head flat, or nearly so; upper incisors close to canines; ears moderate, separate. Genera.—Vespertilio, Vesperugo, Chalinolobus, Scotophilus, Nyeticejus, Atalapha, and Kerivoula.Group 2.—Plecoti.—Head and incisors as above; ears very large, generally united. Genera—Plecotus, Synotus, Histiotus, Otonycteris, Coriuorhinus, Nyctophilus, and Antrozous.Group 3.—Miniopteri.—Crown greatly elevated; upper incisors separated from canines. Genera.—Natalus, Miniopterus, and Thyroptera.B.—Emballonurine Alliance.Family V.—EMBALLONURIDÆ.Sub-family 1.—Emballonurinæ.—Tail slender; upper incisors weak.Group 1.—Emballonuræ.—Frontal bones convex. Genera.—Furia, Saccopteryx, Rhynchonycteris, and Emballonura.Group 2.—Taphozoi.—Frontal bones with a concavity; pre-maxillary bones separate in front. Genera.—Coleura, Taphozous, Diclidurus.Group 3.—Rhinopomata.—Frontal bones concave; pre-maxillaries united (a small nose-leaf). Genus.—Rhinopoma.Group 4.—Noctiliones.—First phalanx of middle finger extended in repose. Genus.—Noctilio.Sub-family 2.—Molossinæ.—Tail thick; upper incisors strong.Group 5.—Molossi.—Middle finger with two phalanges. Genera.—Mormopterus, Molossus, Nyctinomus, and Chiromeles.Group 6.—Mystacinæ.—Middle finger with three phalanges. Genus.—Mystacina.Family VI.—PHYLLOSTOMIDÆ.Sub-family 1.—Lobostominæ.—Nostrils in front of muzzle; chin with erect cutaneous ridges. Genera.—Chilonycteris, Pteronetus, Mormops.Sub-family 2.—Phyllostominæ.—Nostrils on upper surface of muzzle; chin with warts.Group 1.—Vampyri.—Molars with W-shaped cusps; four upper incisors; muzzle long; tongue moderate. Genera.—Macrotus, Lonchorhina, Macrophyllum, Vampyrus, Schizostoma, Lophostoma, Trachyops, Phyllostoma, Carollia, Rhinophylla.Group 2.—Glossophagæ.—Like the Vampyri, but tongue very long, and lower lip divided by a deep groove. Genera.—Glossophaga, Monophyllus, Ischnoglossa, Phyllonycteris, Lonchoglossa, Glossonycteris.Group 3.—Stenodermata.—Muzzle short; molars with a cutting outer edge; four upper incisors. Genera.—Stenoderma, Artibeus, Phyllops, Vampyrops, Pygoderma, Ametrida, Chiroderma, Sturnira, Brachyphylla, Centurio.Group 4.—Desmodontes.—No true molars; two upper incisors. Genera.—Desmodus, Diphylla.

SUB-ORDERI.—MEGACHIROPTERA.

Family I.—PTEROPIDÆ.

Group 1.—Pteropi.—Tongue moderate; molars well developed. Genera.—Pteropus, Cynopterus, Cynonycteris, Harpyia, Epomophorus, Hypsignathus, and Cephalotes.Group 2.—Macroglossi.—Tongue very long; molars very small. Genera.—Macroglossus, Eonycteris, and Notopteris.

SUB-ORDERII.—MICROCHIROPTERA.

A.—Vespertilionine Alliance.

Family II.—RHINOLOPHIDÆ.

Sub-family 1.—Rhinolophinæ.—First toe with two, remainder with three phalanges. Genus.—Rhinolophus.Sub-Family 2.—Phyllorhininæ. Toes equal, each of two phalanges. Genera.—Cœlops, Phyllorhina, Rhinonycteris, and Triænops.

Sub-family 1.—Rhinolophinæ.—First toe with two, remainder with three phalanges. Genus.—Rhinolophus.

Sub-Family 2.—Phyllorhininæ. Toes equal, each of two phalanges. Genera.—Cœlops, Phyllorhina, Rhinonycteris, and Triænops.

Family III.—NYCTERIDÆ.

Sub-family 1.—Nycterinæ.—Nasal apparatus concealed; tail long. Genus.—Nycteris.Sub-family 2.—Megaderminæ.—Nose-leaf distinct; tail short. Genus.—Megaderma.

Sub-family 1.—Nycterinæ.—Nasal apparatus concealed; tail long. Genus.—Nycteris.

Sub-family 2.—Megaderminæ.—Nose-leaf distinct; tail short. Genus.—Megaderma.

Family IV.—VESPERTILIONIDÆ.

Group 1.—Vespertiliones.—Crown of head flat, or nearly so; upper incisors close to canines; ears moderate, separate. Genera.—Vespertilio, Vesperugo, Chalinolobus, Scotophilus, Nyeticejus, Atalapha, and Kerivoula.Group 2.—Plecoti.—Head and incisors as above; ears very large, generally united. Genera—Plecotus, Synotus, Histiotus, Otonycteris, Coriuorhinus, Nyctophilus, and Antrozous.Group 3.—Miniopteri.—Crown greatly elevated; upper incisors separated from canines. Genera.—Natalus, Miniopterus, and Thyroptera.

B.—Emballonurine Alliance.

Family V.—EMBALLONURIDÆ.

Sub-family 1.—Emballonurinæ.—Tail slender; upper incisors weak.Group 1.—Emballonuræ.—Frontal bones convex. Genera.—Furia, Saccopteryx, Rhynchonycteris, and Emballonura.Group 2.—Taphozoi.—Frontal bones with a concavity; pre-maxillary bones separate in front. Genera.—Coleura, Taphozous, Diclidurus.Group 3.—Rhinopomata.—Frontal bones concave; pre-maxillaries united (a small nose-leaf). Genus.—Rhinopoma.Group 4.—Noctiliones.—First phalanx of middle finger extended in repose. Genus.—Noctilio.Sub-family 2.—Molossinæ.—Tail thick; upper incisors strong.Group 5.—Molossi.—Middle finger with two phalanges. Genera.—Mormopterus, Molossus, Nyctinomus, and Chiromeles.Group 6.—Mystacinæ.—Middle finger with three phalanges. Genus.—Mystacina.

Sub-family 2.—Molossinæ.—Tail thick; upper incisors strong.Group 5.—Molossi.—Middle finger with two phalanges. Genera.—Mormopterus, Molossus, Nyctinomus, and Chiromeles.Group 6.—Mystacinæ.—Middle finger with three phalanges. Genus.—Mystacina.

Family VI.—PHYLLOSTOMIDÆ.

Sub-family 1.—Lobostominæ.—Nostrils in front of muzzle; chin with erect cutaneous ridges. Genera.—Chilonycteris, Pteronetus, Mormops.Sub-family 2.—Phyllostominæ.—Nostrils on upper surface of muzzle; chin with warts.Group 1.—Vampyri.—Molars with W-shaped cusps; four upper incisors; muzzle long; tongue moderate. Genera.—Macrotus, Lonchorhina, Macrophyllum, Vampyrus, Schizostoma, Lophostoma, Trachyops, Phyllostoma, Carollia, Rhinophylla.Group 2.—Glossophagæ.—Like the Vampyri, but tongue very long, and lower lip divided by a deep groove. Genera.—Glossophaga, Monophyllus, Ischnoglossa, Phyllonycteris, Lonchoglossa, Glossonycteris.Group 3.—Stenodermata.—Muzzle short; molars with a cutting outer edge; four upper incisors. Genera.—Stenoderma, Artibeus, Phyllops, Vampyrops, Pygoderma, Ametrida, Chiroderma, Sturnira, Brachyphylla, Centurio.Group 4.—Desmodontes.—No true molars; two upper incisors. Genera.—Desmodus, Diphylla.

Sub-family 1.—Lobostominæ.—Nostrils in front of muzzle; chin with erect cutaneous ridges. Genera.—Chilonycteris, Pteronetus, Mormops.

Sub-family 2.—Phyllostominæ.—Nostrils on upper surface of muzzle; chin with warts.Group 1.—Vampyri.—Molars with W-shaped cusps; four upper incisors; muzzle long; tongue moderate. Genera.—Macrotus, Lonchorhina, Macrophyllum, Vampyrus, Schizostoma, Lophostoma, Trachyops, Phyllostoma, Carollia, Rhinophylla.Group 2.—Glossophagæ.—Like the Vampyri, but tongue very long, and lower lip divided by a deep groove. Genera.—Glossophaga, Monophyllus, Ischnoglossa, Phyllonycteris, Lonchoglossa, Glossonycteris.Group 3.—Stenodermata.—Muzzle short; molars with a cutting outer edge; four upper incisors. Genera.—Stenoderma, Artibeus, Phyllops, Vampyrops, Pygoderma, Ametrida, Chiroderma, Sturnira, Brachyphylla, Centurio.Group 4.—Desmodontes.—No true molars; two upper incisors. Genera.—Desmodus, Diphylla.

We have already remarked that of these families the Vespertilionidæ may be regarded as the types of the whole order; they realise all the notions that we form in our minds when we speak of “a Bat,” and this with the greatest simplicity, or with the smallest amount of complication from subordinate characters. Next to them in this respect come some of the Emballonuridæ. The other families group themselves round these, or the whole of the other Microchiroptera may be said to surround the Vespertilionidæ. Mr. Dobson, accepting the notion of the origin of organic forms by a process of evolution, assumes an unknown group of ancestral forms (Palæochiroptera) from which in the first place the Vespertilionidæ and Emballonuridæ diverge, forming the roots of his two “alliances.” From the Emballonuridæ proceed the Phyllostomidæ, and from the Vespertilionidæ the Nycteridæ and Rhinolophidæ. From this point of view these Bats may be regarded as allied to the Insectivora through some unknown common ancestors; but what these may have been, or by what stages the Bat-type originated from the ordinary quadruped, it is very difficult to imagine. The facts of geographical distribution go far, however, to confirm the view that the Vespertilionidæ and Emballonuridæ are the central and oldest types of Bats; their distribution is world-wide, and even some nearly allied forms are found in very distant parts of the world. The other families are more restricted in their range, the Nycteridæ and Rhinolophidæ being confined to the Eastern, and the Phyllostomidæ to the Western hemisphere, and chiefly to the warmer zones, whereas the Vespertilionidæ extend much further to the north.

The Pteropidæ, or Frugivorous Bats, however, cannot well be brought into this scheme of descent. They stand completely isolated from the rest of the order, and their peculiar distribution would almost seem to indicate that their origin and relationships were distinct from those of the other Bats. Their range, which sweeps round the shores of the Indian Ocean from the Cape of Good Hope to Australia, and extends, perhaps somewhat exceptionally, into the islands of the Pacific, although it cannot be said to coincide with that of the Lemuroids, being so much wider, at least includes the whole of the localities in which the latter are met with; and if the Lemuroids are really, as seems probable, segregated descendants of a great fauna which inhabited the supposed sunken continent of “Lemuria,” the same origin may fairly be ascribed to the Pteropidæ, and their wider distribution may be accounted for by their much greater power of locomotion. In connection with this it is interesting to note the strong Lemurian resemblances presented by many of the Pteropidæ; and further, the sort of common point of junction between the Lemuroids, the Pteropids, and the Insectivora, furnished by that curious animal theGaleopithecus, or Flying Lemur, which is also still an inhabitant of a region haunted by Lemuroids and Pteropine Bats. The Pteropidæ thus seem to stand quite apart from the other Bats. From a genealogical point of view, which indeed is that which we always take of the relationships of animals, whether we believe in the doctrine of descent or not, we may ask whether the two sub-orders of Bats have not been realised in their present form through two quite different series of modifications.

The appeal to fossil evidence, which in some cases leads to satisfactory results, gives us no clue to the origin of the different groups of Bats. Of the Pteropidæ no fossil remains are known. Of the other families the most ancient remains are, as might be expected, those of the Vespertilionidæ, several species of which have been found in Miocene beds at Mayence and in the south of France, and even in the Eocene gypsum deposits of the Paris basin. Other bones identical with those of species now living in the same localities have been detected in bone-caves in various parts of Europe. Bones of aRhinolophushave occurred in the cavern of “Kent’s Hole,” near Torquay; and the celebrated bone-caves Brazil have furnished numerous remains of Bats, all of which, however, are referable to the peculiarly South American family Phyllostomidæ. Thus, so far as we are acquainted with them, the fossil remains of Bats, even the most ancient, indicate only forms more or less nearly related to those still existing in the same localities, and furnish us with no means even of speculating upon the course of events by which, so to speak, the type of the Chiroptera was evolved.

W. S. DALLAS.

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