OPOSSUM AND YOUNG.⇒LARGER IMAGE
OPOSSUM AND YOUNG.⇒LARGER IMAGE
OPOSSUM AND YOUNG.
⇒LARGER IMAGE
Prehistoric Opossums—Description of the Animal—Their Teeth—Habits—THECOMMONOPOSSUM—Appearance—Use of its Tail—Food—The Young—How they are Reared—D’AZARA’SOPOSSUM—THECRAB-EATINGOPOSSUM—THETHICK-TAILEDOPOSSUM—MERIAN’SOPOSSUM—Pouchless Opossums—Their Young—THEMURINAOPOSSUM—THEELEGANTOPOSSUM—THEYAPOCK—Classification of Marsupial Animals—Geographical Distribution of the Sub-Order—Ancestry of the Marsupials—Fossil Remains.
Prehistoric Opossums—Description of the Animal—Their Teeth—Habits—THECOMMONOPOSSUM—Appearance—Use of its Tail—Food—The Young—How they are Reared—D’AZARA’SOPOSSUM—THECRAB-EATINGOPOSSUM—THETHICK-TAILEDOPOSSUM—MERIAN’SOPOSSUM—Pouchless Opossums—Their Young—THEMURINAOPOSSUM—THEELEGANTOPOSSUM—THEYAPOCK—Classification of Marsupial Animals—Geographical Distribution of the Sub-Order—Ancestry of the Marsupials—Fossil Remains.
THEMarsupial animals included in this family are not found in Australia or in Van Diemen’s Land, or in any part of the natural history province to which those countries belong. They are numerous, however, and are now living on the American continent; but formerly some inhabited Europe during that geological period which is called the Eocene. The Opossums are very rat-like in form, the largest species being about the size of a large Cat, but they have the snout more elongated; and in some species in which the individuals are large the body is proportionately stout, and on most there is a comfortable fur, with short and long hair. The tail is almost always very long, nearly destitute of hair, excepting at the root, and is covered with a scaly skin, there being a few scattered hairs. It is a useful organ, for the Opossums hang by it, and it assists them in climbing and descending trees, and in holding on, when they are young, to their parent. The ears are rather large and round, the eyes are placed rather high up in the face, and the long muzzle ends in a naked snout. The legs look short for the body. The feet are naked beneath; there are five toes, and the great toe is more or less opposable to the foot, and acts like a grasping thumb. Each toe is furnished with moderate-sized claws, excepting the inner toe of the hind foot, which is clawless. The Opossums are remarkable for the great number of their incisor teeth, there being ten in the upper and eight in the lower jaw, and they are arranged in a semicircular manner. The upper and two foremost incisors are rather longer than the rest, and are generally separated from them by a narrow space. They are nearly cylindrical and expanded at the tip. The canines are well developed, the upper ones being the largest. There are three premolars on each side of both jaws, and they have two roots, and are compressed and pointed. There is a posterior talon to them. The molars, eight in each jaw, have three roots, and those of the upper jaw have the crown of a triangular form and tubercular, whilst those of the lower jaw are longer than broad, and each has the appearance of five prickly cusps on its upper surface.
TEETH OF THE OPOSSUM.
TEETH OF THE OPOSSUM.
Some of the Didelphidæ have no marsupium, or pouch, or it is very slightly developed, and in these particular kinds the young, after having left the nipples, are carried on the back of the mother, retaining their position by twining their tails around hers. The mammæ are numerous: there may be as many as thirteen, an odd one being found in the centre of the ring of the other nipples.
The Opossums are active, sly, and very intelligent in certain things, and their food consists of insects, small reptiles, birds, and eggs. Living for the most part in trees, they secrete themselves inthe hollows of the branches and trunks during the daytime and sally forth in the night. They have a moderate-sized cæcum. It must be noticed that the great toe of the hind foot is well developed, has no nail, and enables the creature to grasp, and is thus very useful; and that they walk plantigrade. The ankle and leg have the same movements as in the Wombats, and the same general anatomy. If the members of the family are compared with those of the families which live in the Australian province, it will be found that they most resemble the Perameles and Dasyures. The Opossums may be divided into three groups: those whose pouch is well developed, those in which it is a mere fold, and those which have webbed feet and live in the water, like Otters.
SKELETON OF THE CRAB-EATING OPOSSUM.
SKELETON OF THE CRAB-EATING OPOSSUM.
THE COMMON OPOSSUM.[123]
This is a large kind, and is about the size of a common Cat, and its long, large, pointed head, ending in a naked snout, and having eyes encircled in dusky brown fur amongst the white hair and fur of the head, gives it a very cunning and thoughtful appearance. The ears are black. The tail is long and prehensile, the end being white and the rest black, and the legs and feet are brownish. It is a great climber, and uses its tail almost as much as some of its Monkey companions. Running along the branches, it will often suspend itself by its tail, and give a swing and let go, thus launching its body to a distance, and then it catches at the boughs with its feet and unclawed but prehensile hind toe-thumb. In coming down trees it uses the tail to steady itself, and to prevent too rapid a fall; and in climbing, the ever-ready tail prevents mishaps, should the clawed toes not grasp sufficiently. The natural food of this Opossum is probably vegetarian, but it is a great birds’-nester; it will eat roots and fruits, but the early settlers found it very destructive to their poultry, for it catches the birds and sucks their blood, not eating the flesh: consequently, it has been much hunted, and as the fur and skin are sometimes used, the destruction of the Opossum has been great. It is a curious creature, and seems to have gained experience in its struggle with man, and as many stories are told of its cleverness as there are about Reynard the Fox and the Indian Jackal. It will sham death in a most persevering manner, and is at the same time very tenacious of life.
The skull has strong temporal ridges, which form a sagittal crest, and the arch of the zygoma is well grown. The animal has a longer facial part of the skull and a smaller brain-case than the other Dasyures, and the brain has large olfactory or front lobes. The cerebral hemispheres are small, and there are no convolutions. This is essentially a North American animal, and is found from Mexico to the Southern States inclusive.
The female brings forth from twelve to sixteen young at a time, and her nest, which is formed of dry grass, is usually at the root of a tree or bush. When first born, the young are said not to bemore than a grain in weight, and blind, naked, and shapeless. They find the teats in the mother’s pouch, unless she places them on to them with her mouth, and they cling on so as not to be separated except by violence. In about five days, so rapid is their growth, they have reached the size of a Mouse, and all their parts are developed. They then leave the pouch, and return to suckle and when danger appears. During this time the female shows great attachment to her young; and Mr. Waterhouse, from whose work these descriptions are taken, states that she will suffer any torture rather than permit the pouch to be opened.
CRAB-EATING OPOSSUM.
CRAB-EATING OPOSSUM.
AZARA’S OPOSSUM.[124]
This is a smaller animal than the common or Virginian Opossum, but its tail is long in proportion to its body. It is the South American representative of its larger fellow species, and is found over a very wide extent of country. It was noticed by the celebrated naturalist D’Azara in Paraguay; Mr. Darwin found it at Maldonado, La Plata; and specimens have been obtained from the Brazils, Santa Fé de Bogota, and Bolivia. This is because it is not entirely a forest animal, but is found occasionally in the open country. It may be distinguished from the common Opossum by three distinct black marks on its head, by its large tail, one-third of which is covered with fur like that on the body. The rest of this important member is scaly, with small hairs springing from between, thescales being black in the second third, and white at the tip in colour. The habits of this Opossum are nocturnal, and it lies concealed by day in burrows in the ground or in thickets. At night it climbs trees to feed upon fruits and birds’ eggs. It will chase and catch sleeping birds, and suck their blood like a Weasel.
THE CRAB-EATING OPOSSUM.[125]
A small Opossum, with a long black tail tipped with white, and a dull-coloured fur to its body, lives in Brazil and Guiana, and has a very omnivorous disposition. Preferring swampy situations, it lives mostly on the trees, hunts small birds and insects, and even catches a reptile now and then, but its fondness for the Crustacea of the swamps is proverbial, and hence its name of Crab-eater.
Another species is interesting from being found in the part of California which adjoins Mexico. The Short-headed Opossum also belongs to this group, and is from the same locality. Besides these, there are several smaller pouch-bearing Opossums, without the long hair of those just mentioned, and they are from Brazil, Guiana, and Surinam—for instance, the Quica, the Naked-tailed, and the Four Spotted kinds. The Philander Opossum is a bird-hunter, and lives in Surinam.
The next group of Opossums have no pouch, but there may be folds of the skin protecting the mammæ.
THE THICK-TAILED OPOSSUM.[126]
As its name implies, this pouchless Opossum has a very thick tail. Moreover, it has smaller ears than the other Opossums, and has a short head and short legs. The fur is made up of harsh hairs, which are close to the body, and there is but little under fur. Its colour is yellow-brown, but the eye and muzzle are brownish, and the tail, with the terminal two-thirds, is black, with the exception of a small white spot at the end. It inhabits Brazil and Paraguay, and extends southwards to the River Plate. One of the Opossums was kept by D’Azara, who found it quiet, tame, and stupid; but having been fed on raw meat, and a parrot happening to come too close, it killed the bird in a moment. There are folds of skin in the lower part of the abdomen, but no pouch, and there are six mammæ.
Another of the Opossums is called Merian’s Opossum, orDidelphys dorsigera, and it inhabits Surinam. It was described by Madame Merian in 1717, who represented it in her great book on insects with its young clustered on its back and hanging on to the mother’s tail, which was curved over its back, with their little tails.
MERIAN’S OPOSSUM.
MERIAN’S OPOSSUM.
It is very curious that the young of these pouchless Opossums should resemble those of the whole order in being comparatively little advanced in their development at the time of their birth. The young are at first strongly attached to the teats of the mother, and when they are sufficiently strong and grown to leave them, occasionally she takes them off from the nipples and places them on her back. Here they cling on with their tails to hers. Hence the name of back-bearing, or Dorsigera, which is given to this kind.
YAPOCK.
YAPOCK.
It was at first supposed that this method of carrying the young was restricted to this species, but subsequent experience has shown that several kinds do the same thing.
Two or three other species of Opossum are interesting from their small size and habits. Thus the Murina Opossum (Didelphys murina), with a very long tail, inhabits Guiana, Brazil, Peru, and Mexico. The body is about five inches in length, and the tail is either slightly longer or about the same. Yet this little thing attacks birds and insects; it burrows in the ground, and climbs trees to get its insect food.
The Elegant Opossum (Didelphys elegans), of Chili, is still smaller than the last, and frequents the thickets growing on the rocky hills near Valparaiso. They are numerous, or were so when Mr. Darwin observed them, and are easily caught in traps baited with cheese or meat. The tail appeared to be rarely, if at all, used as a prehensile organ; yet they could run up trees with some degree of facility. It is an interesting fact that some of the smallest Opossums prey upon Lizards and Snakes as large, and even heavier, than themselves.
The last section of the Opossums contains the Water Opossum.
THE YAPOCK.[127]
This animal has a perfect pouch, and has large hind feet, the toes of which are united by a web. The fore feet are moderate-sized, and the pisiform bone is unusually long. Its habits are aquatic.The Yapock has large naked ears, and a long, almost naked, tail, and is altogether rather larger than the common Rat. Its method of life is very much the same as that of the Otter. It is a good diver, and feeds upon crustaceous and other aquatic animals. It is a native of Guiana and Brazil.
The Marsupial animals assume the general shape and habits of many orders of Mammalia which have no marsupium, and which live in the other great natural history provinces. Thus there are Marsupial animals like Dogs, Rats, Squirrels, Flying Squirrels, Deer, &c. They have, therefore, many methods of life as a group, and, as might be expected, the brain and nervous system present many differences in them. In all, the front lobes of the brain which deal with the sense of smell are very large, and in some, such as in the Carnivorous Marsupials, they are exposed, and not covered by the main mass of the brain. In the Kangaroos, however, these olfactory lobes are hidden more or less. These last also have well-marked convolutions on the brain which are nearly wanting in those first mentioned.
The Marsupial animals just considered have been classified to a certain extent during their descriptions, but it is necessary to recapitulate. They are arranged in groups of genera or species, or into families. They are as follows:—
ORDER MARSUPIALIA.—SUB-ORDER MARSUPIATA.
Family
MACROPODIDÆ
Genus
Macropus
Kangaroos.[128]
„
Dendrolagus
Tree Kangaroos.
„
Hypsiprymnus
Potoroos.
„
Hypsiprymnodon
The Hypsiprymnodon.
„
PHASCOLOMYIDÆ
„
Phascolomys
The Wombat.
„
PHALANGISTIDÆ
„
Phascolarctus
The Koala.
„
Phalangista
The Cuscus.
Dormouse Phalanger.
Phalangers.
„
Petaurus
Flying Phalangers.
„
Tarsipes
Tarsipes.
„
PERAMELIDÆ
„
Perameles
Bandicoots.
„
Chœropus
Chœropus.
„
DASYURIDÆ
„
Myrmecobius
Ant-eaters.
„
Phascogale
Phascogale.
„
Dasyurus
Dasyures.
„
Thylacinus
Dog-headed Thylacinus.
„
DIDELPHIDÆ
„
Didelphys
Opossum.
„
Chironectes
Yapock.
The Macropodidæ, Phalangistidæ, Peramelidæ, and Dasyuridæ are found living somewhere or other in the Australian distributional province, which includes the mainland, Tasmania to the south, and the Molucca and Arru Islands to the north, bounded by the Straits of Lombok, and Celebes, New Guinea, New Ireland, Timor, Amboyna, Banda, and Waigeoe. Each family is not represented fully, however, in all the remarkably separated divisions of the province. Thus the genera Macropus and Dendrolagus of the first family, Petaurus and Phalangista of the third, Perameles of the fourth, and Phascogale of the Dasyuridæ have been found in New Guinea; but in other islands, such as Celebes, and in those from Lombok to Timor, the genus Cuscus alone is represented. In the Moluccas, Cuscus and the genus Petaurus are found. In Van Diemen’s Land about one-half of the species are peculiar to the island, and the remainder are found also on the eastern districts of the mainland. It has Kangaroos, Potoroos, Wombats, Phalangers, Bandicoots, and three out of the four genera of Dasyuridæ. Western Australia, which is such a remarkable botanical province, and is so separated by desert and sand from the east, has numerous Kangaroos, Potoroos, Phalangers, Bandicoots,Phascogales, Dasyures; and, in common with South Australia, a Chœropus, whilst the genus Tarsipes is peculiar to it. The Wombat is found in Van Diemen’s Land and some of the islands in Bass Strait. It is found in the south and east of the mainland of Australia, but not to the west and north. Mr. Waterhouse notices that the Marsupials of the eastern districts are for the most part distinct from those of the opposite side of the continent, there being, when his great work, which has been so constantly referred to in this description, was written, but eight species out of upwards of sixty inhabiting the two provinces. South Australia is the habitat of more common species than elsewhere. The northern part of Australia has more species peculiar to it than the other divisions, and some of its Dasyuridæ especially, and species of Cuscus also, are found in the Arru and other islands to the north. The metropolis of the sub-genus Cuscus is in the Moluccas, where two species are widely distributed, or one is restricted to certain islands.
The other divisions of the genus are represented by the Vulpine Phalanger, an animal with long loose fur, which inhabits New South Wales, Western Australia, and North Australia; by Cook’s Phalanger, of New South Wales and Van Diemen’s Land. The genus Perameles, the Bandicoots, has species in Van Diemen’s Land, Australia, New Guinea, and in the Arru Islands, and the genus Petaurus has a corresponding distribution. The Didelphidæ are found in the United States, California, Mexico, Peru, Guiana, Brazil, Paraguay, Banda Oriental, and Chili; and Brazil is the country where they abound the most in species and individuals, the number diminishing to the north and south.
The Marsupials have a great ancestry, and some of them lived when the continents and oceans of the earth were in very different relative positions to those they now occupy. Indeed, it is most probable that the fossil remains of the most ancient mammal belong to this order. There is a small double-fanged molar tooth of a mammal which was found by Plieninger, in 1847, contained in a jumble of shells and of the remains of reptiles and fishes in strata beneath the Lias formation of Diegerloch, near Stuttgart. It and another which was discovered close by, by the same professor, belonged to animals which were dead when this topmost stratum of the Trias, immediately beneath the Lias, was being formed. They are Triassic in age, therefore, and they somewhat resemble the back teeth of a fossil which was found subsequently in the Purbeck strata of England, and which evidently belonged to a Marsupial more or less resembling the existing Kangaroo-Rats or Potoroos, of the genus Hypsiprymnus. Later on, Professor W. Boyd Dawkins, F.R.S., discovered a small tooth belonging to the same extinct genus as that which included Plieninger’s fossil, namely, Microlestes; and its resemblance to one of Hypsiprymnus is even greater. Its position was high up in the Trias of Watchet in Somersetshire. Mr. Charles Moore, of Bath, had previously found many specimens of teeth of the same family in a fissure, down which they had been washed by the Triassic sea.
A lower jaw of a small Mammal was found in the Trias of North America by Emmons; and it has on one side three incisors, one long canine, then a diastema, three premolars, and seven molars with three points. It is therefore one of the Myrmecobius group.
After the age of the Trias, when there was much continuous land surface, Europe was broken up into a coral island tract, during the age of the collection of the Jurassic deposits. The islands were tenanted by many small Marsupials, four species of which have been discovered in the deposits of Stonesfield slate at the bottom of the Great Oolite. They belong to the extinct genera Amphitherium, Phascolotherium, and Stereognathus, and the first somewhat resembled the Myrmecobius of recent times; but all that can be said is that they belonged to Marsupial animals. Piled on the Stonesfield slates are many hundred feet of strata, and high up amongst them, in the Swanage and Purbeck districts, are deposits in which Messrs. Brodie and Beckles have found portions of the skeletons of numerous insectivorous Marsupials, of which the genera Spalacotherium, Plagiaulax, Triconodon, and Galestes are the most important. They were small, as a rule, and there has been much debate regarding their affinities with modern insectivorous forms, and they are still surrounded with doubt.
The appearance of the Mammalia without pouches took place in the Eocene age, and in the Old and New World, and contemporaneously with them lived in France a kind of Opossum, some of whose bones were found in the strata of Montmartre, near Paris; and in later Tertiary strata other relics have been found. These are the only instances of a fossil Didelphid occurring out of the New World; and there, where the Opossums are now characteristic animals, they were present in the last geological age, for in the Brazilian latest deposits remains of several species of Didelphys have been found.Remains of these fossil Opossums have been found in the North American Pliocene deposits. The more ancient deposits of Australia have not yielded the remains of any of the animals which are now so peculiar to the province, but in the bone caves of the Wellington Valley, some two hundred and ten miles west of Sydney, Sir Thomas Mitchell discovered a mass of bones, forming a breccia with limestone, which contained numerous and most interesting Marsupial remains. In deposits of the same late age, and in bogs and gravels in Queensland, other remains were found. They were described by Sir R. Owen in one of his greatest works, and they belong to the Australian families of Marsupials, and not to the American Didelphidæ. As was usual elsewhere before the appearance of man on the earth, and contemporaneously with him for awhile, many of the kinds which resemble more or less those now living, or would be classified in the same family, and perhaps in the same genus, are gigantic. Owen distinguished among the bones those of large fossil Marsupials which belong to the Macropodidæ, and which may be arranged as subdivisions of the genus Macropus or Kangaroos, and of a powerful creature called Thylacoleo, or Pouched Lion, which must be admitted as a new section of the Macropodidæ, and whose habits were probably carnivorous, although there is much diversity of opinion on the subject, some of the most distinguished anatomists believing the creature to have been of an innocent disposition, although appearances are much against it. It is more closely allied to Plagiaulax, of the English Purbeck beds, than to any other form, and they well fit in between the genera Macropus and Hypsiprymnus.
A huge Marsupial, with a skull three feet in length, with teeth, in front especially, on the Kangaroo plan, and with longer fore limbs and shorter hind ones than the last-named animal, was described by Owen. The pelvis, however, has but two sacral vertebræ, and its ilio-pubic process would ally it with the Macropodidæ. This Diprotodon was an herbivorous animal, and was of the size of a Rhinoceros. This great Marsupial had fore limbs which possessed the power of rotation, and it was not without some characters which are seen amongst the Wombats. It appears to have had a great range, for its remains have been found in the caverns in the Wellington Valley, at Welcome Springs, South Australia, Hergolt’s Springs, 500 miles north of Adelaide, near Melbourne, in the valley of the Condamine River, and widely over Queensland. A slightly smaller animal, called the Nototherium, also existed with the larger one.
The species of this genus have no lower incisive tusks, and a very short chin; the angle of the jaw is curved inwards, and there were only four molar teeth on each side in both jaws, and they were with two strong roots or fangs. It was probably one of the Macropodidæ. Others of this family are allied to Dendrolagus, and form the genera Protemnodon and Sthenurus. The Wombat was represented in the age of the great Marsupials; and both large and small species, one being of the size of the Tapir, have been described from bones and teeth which were found in the cave deposits of Australia. Remains of a Marsupial animal, probably of the Vulpine Phalanger, were found in the same caves, as were also some referable to the genus Perameles, or Bandicoots, and to the Potoroos. Several fossil species of the family Dasyuridæ have been found in the Australian caves, and one of them is referable to a section of the genus Dasyurus, which at present is restricted to Van Diemen’s Land, it being somewhat likeDasyurus ursinus; moreover, probably, there was a species of Thylacinus present also. So far as is known from the researches of Owen amongst this wonderful cave fauna, no members of the family Didelphidæ occur there. They were American then, as they are now.