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 is caused.[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 genera Desmodus and Diphylla. With the latter he had no acquaintance, but he obtained Desmodus rufus in 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.
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 (g in [figure]) 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, and limit 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.