The Cambridge Natural History Part 11

FAM. 1. DASYURIDAE.--This family consists of Marsupials which are generally pentadactylous, but with occasionally the hallux missing. The tail is long but not prehensile. The pouch is present or absent. The teeth vary in the different genera, but {150} the upper incisors are never less than three, and may be as many as five in the upper jaw and six in the lower. The canines are trenchant. There is no caec.u.m.

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FIG. 77.--Front view of skull of Koala (_Phascolarctos cinereus_), ill.u.s.trating Diprotodont and herbivorous dent.i.tion. (From Flower.)

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FIG. 78.--Longitudinal section of the skull of the Thylacine (_Thylacinus cynocephalus_). . _a_, Angular process of mandible; _AS_, alisphenoid; _BO_, basioccipital; _BS_, basisphenoid; _cd_, condyle of mandible; _ET_, ethmoturbinal; _Ex.O_, exoccipital; _Fr_, frontal; _ME_, ossified portion of mesethmoid; _MT_, maxilloturbinal; _Mx_, maxilla; _Na_, nasal; _OS_, orbitosphenoid; _Pa_, parietal; _Per_, periotic; _Pl_, palatine; _PMx_, premaxilla; _PS_, presphenoid; _Pt_, pterygoid; _SO_, supraoccipital; _Sq_, squamosal; _Vo_, vomer. (From Flower's _Osteology_.)

The genus _Thylacinus_ contains but a single species, which is now limited to Tasmania, and is generally known as the Tasmanian Wolf. It has the build of an ordinary Wolf, and is of about the same size. The hinder part of the body is marked with a series of black transverse bands. The hallux is entirely wanting; the pouch opens backwards. The marsupial bones are minute and unossified. The dental formula is I 4/3 C 1/1 Pm 3/3 M 4/4 = 46. There are four mammae. This animal, now confined to Tasmania, {151} is getting rarer on account of its sheep-killing propensities, and the consequent war of extermination declared upon it by the colonists. It will, however, feed upon other animals; and it is related that the first specimen ever captured had in its stomach the remains of an Echidna! Mr. Thomas thinks that the persistence of this and of some of the other larger carnivorous Marsupials in Tasmania after their extinction in Australia is not unconnected with the advent of the Dingo. But it is stated that the Thylacine is quite capable of keeping even a pack of dogs at bay.

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FIG. 79.--Tasmanian Devil. _Sarcophilus ursinus._ 1/10.

The genus _Sarcophilus_ has been frequently confounded with the next, but it is kept apart by Mr. Thomas, who follows Cuvier in this. An alternative generic name is _Diabolus_, which, like the first name, refers to the habits and character of the single species which this genus contains. The genus is more like _Thylacinus_ than is _Dasyurus_. The hallux is wanting, and the teeth, though fewer in number (42), resemble those of the Thylacine more closely than do those of the Dasyure. The species is called _S.

ursinus_, the popular name being Tasmanian Devil. It is black with a variable number of white patches on the body. It is of about the size of a Badger, and is, like the Thylacine, a nocturnal animal. The Tasmanian Devil is said to be one of the most ferocious of animals, and to express its ferocity by a "yelling growl."

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FIG. 80.--Skull of _Dasyurus_. (Lateral view.) _al.sph_, Alisphenoid; _ang_, angular process of mandible; _fr_, frontal; _ju_, jugal; _lcr_, lachrymal; _max_, maxilla; _nas_, nasal; _oc.cond_, occipital condyle; _par_, parietal; _par.oc_, paroccipital process; _p.max_, premaxilla; _s.oc_, supraoccipital; _sq_, squamosal; _sq_', zygomatic process of squamosal. (From Parker and Haswell's _Zoology_.)

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FIG. 81.--Dasyure. _Dasyurus viverrinus_. 1/5. (After Vogt and Specht.)

The next genus of this family, _Dasyurus_, comprises five species, which range over the whole of the Papuan and Australian sub-regions. The general form is Viverrine, and the hallux is sometimes present though small. The dental formula is as in the last genus, but the teeth "are more insectivorous in their character." There are six or eight mammae. The members of this genus are grey or brown, and spotted with white; they are all arboreal, and feed largely upon birds and their eggs. Mr. Thomas has pointed out that in two species, _D. viverrinus_ and _D. geoffroyi_, the striae upon the foot-pads are absent, and that therefore these at least are probably not so purely arboreal as the rest. The animals are not diurnal, and during the day hide themselves in the hollow trunks of trees. They are spoken of as "Native Cats," but have the general habits of Martens. _D.

maculatus_ is common in Tasmania, but is rare in Australia, thus "approaching the condition now exhibited by the Thylacine and {153} Tasmanian Devil, namely, complete extermination in Australia, where both once lived." _D. hallucatus_ shows an approach to _Phascologale_ in its five-toed hind-feet and slender build.

_Phascologale_ is a genus which, like the last, is usually arboreal (although not _P. virginiae_ of North Queensland), but is of much smaller size, the species not exceeding the dimensions of a rat. They have no spots, but there is sometimes a stripe down the back. There are thirteen species, which have the same range as the last genus. The hallux is present though small, but the pouch is "practically obsolete," though there is a small fold of skin behind the teats. The rhinarium is naked; the tail is long, "bushy, crested, or nearly naked." The mammae are four to ten in number. The dental formula is as in _Dasyurus_, and the teeth are not very different in form; sometimes the last premolar is wanting. "The members of this genus," remarks Mr. Thomas, "evidently take the place in the Australian region filled in the Oriental by the Tupaiae, and in the Neotropical by the smaller Opossums."

The genus _Sminthopsis_ comprises not more than four species, even smaller than the last. The largest species, _S. virginiae_, is only 125 mm. in length. The hallux is present, and there is a well-developed pouch. There are forty-six teeth, as in the Dasyures. The feet are narrow with granulated or hairy soles, whereas in _Phascologale_ they are broad with smooth soles. The mammae are eight or ten. The genus ranges through Australia and Tasmania.

The genus _Antechinomys_ has but a single species, which is a native of Queensland and New South Wales. The build is Jerboa-like, and the animal is, as might be inferred, terrestrial. The ears are very long, and the limbs elongated; the hallux is absent; the teeth are exactly as in _Sminthopsis_.

_Antechinomys_ has thirteen dorsal and seven lumbar vertebrae; three sacrals and twenty-five caudals, the latter number being in excess of that of its allies. The stomach is nearly globular, with approximated orifices; the intestine measured 6.8 inches, a little more than twice the length of the animal itself. _A. lanigera_ is a native of East Central Australia, and appears to be entirely terrestrial in habit, and to progress by a series of leaps--at any rate when going at full speed.

Professor Spencer, who found examples of this rare species, gives {154} an interesting description of its habits. _Antechinomys_ has much the look of the Australian Rat, _Hapalotis mitch.e.l.li_; and as the two animals lead a similar kind of life, the resemblance is not unexpected. Professor Spencer wonders why these creatures are saltatory in habit. The country which they inhabit is arid, but with patches of gra.s.s and shrubs. For a big kangaroo the advantage of the power of leaping over such obstacles may be obvious, but not for the small and slender _Antechinomys_. The chief foes of this rare Marsupial appear to be predatory birds; and Professor Spencer thinks that the saltatory mode of progression may be more baffling to such pursuers than even a rapid run.

The genus _Dasyuroides_ has been lately inst.i.tuted by Professor Spencer for a Marsupial from Central Australia somewhat intermediate between _Sminthopsis_ and _Phascologale_. As there is but one species, the generic will be considered with the specific characters. _D. byrnei_ is an animal of about the size of the Common Rat. The hallux is absent. The tail is fairly thick, but not "incra.s.sated." There are six mammae, and the pouch is but slightly developed, with two low lateral folds. The dent.i.tion is I 4/3 C 1/1 Pm 3/2 M 4/4. This Marsupial is nocturnal, and burrowing in habit.

Its food consists of insects.[93]

_Myrmecobius_ is so different from the last-described genera (DASYURINAE) that it is usually separated from them as a sub-family MYRMECOBIINAE. The animal is of a bright rufous colour, banded posteriorly with white. There is no hallux, though the metatarsal belonging to that digit is present.

There are four mammae.[94] On the chest is a naked patch of some extent, upon which open the ducts of a complex gland, which has been described and figured by myself.[95] There is no pouch, but a tract of skin shows indications of a pouch-like structure. The teeth are extraordinarily numerous, fifty to fifty-four; the formula being I 4/3(4) C 1/1 Pm 3/3 M 5/6. Their resemblance to those of certain Jura.s.sic Marsupials is dealt with on p. 100.[96] In this matter lies of {155} course the chief interest of the genus, which may be "an unmodified survivor from Mesozoic times, and therefore from a time long before the Didelphyidae, Peramelidae, and Dasyuridae were differentiated one from the other." Another ancient feature (found in Jura.s.sic mammals) is a mylo-hyoid groove upon the lower jaw, which, however, is not always present, and its existence has therefore been denied. The single species, _M. fasciatus_, is partly arboreal and partly terrestrial in habit, and feeds upon ants. It is a Western and Southern Australian form.

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FIG. 82.--Banded Australian Anteater. _Myrmecobius fasciatus._ 1/5.

FAM. 2. DIDELPHYIDAE.--All the members of this family are pentadactylous.

The teeth are fifty in number, arranged thus: I 5/4 C 1/1 Pm 3/3 M 4/4. The caec.u.m is small; the pouch is generally absent; the tail generally long and prehensile.

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FIG. 83.--Virginian Opossum. _Didelphys virginiana._ 1/5. (After Vogt and Specht.)

The genus _Didelphys_ contains most of the forms belonging to this family, including as it does some twenty-three species. The Opossums are mainly arboreal animals, insectivorous in their food; but the larger species eat reptiles, birds, and their eggs. Several of the small species carry their young, when able to leave the teats, on {156} their back, the tails of the young being wrapped round that of the mother. It is not only the pouched species which carry their young in something of this fashion. Azara's Opossum, an animal as big as a cat, is said to carry its eleven young ones (themselves as large as rats) on the back, though their foothold does not appear to be strengthened by intertwining the tails. Even with this huge family on her back, the mother can climb trees with considerable alacrity.

The mammae are seven to twenty-five in number. The genus has been lately split up into a number of genera, _Marmosa_, _Dromiciops_, _Peramys_, etc.

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FIG. 84.--Thick tailed Opossum. _Didelphys cra.s.sicaudata._ 1/5.

_Chironectes_ is hardly different from _Didelphys_. It has webbed hind-feet, and is aquatic in habit. The one species of the genus is known as the Yapock, and is a Central and South American form. It is of about the size of a large rat, and appears to be an expert diver after the fish upon which it lives.

FAM. 3. PERAMELIDAE.--The Bandicoots, although clearly belonging to the Polyprotodont Marsupials, yet agree with the Diprotodonts in the fact that the second and third toes of the feet are bound up in a common integument, which is not the case with the Diprotodont _Caenolestes_. The hind-feet are longer than the front; of the former limb, two or three of the fingers alone are long and functional; the others are rudimentary or absent. Tail long, hairy, and non-prehensile. Dent.i.tion I 5/3 C 1/1 Pm 3/3 M 4/4 = 48, or sometimes, owing to the absence of a pair of upper incisors, 46. There is a caec.u.m.

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FIG. 85.--Bones of ma.n.u.s. A, of _Ch.o.e.ropus castanotis_. 2. B, of Bandicoot (_Perameles_). 1. _c_, Cuneiform; _l_, lunar; _m_, magnum; _R_, radius; _s_, scaphoid; _td_, trapezoid; _tm_, trapezium; _u_, unciform; _U_, ulna; _I-V_, digits. (From Flower's _Osteology_.)

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FIG. 86.--Rabbit Bandicoot. _Peragale lagotis._ 1/5.

The genus _Peragale_, the Rabbit-Bandicoots, consists of two species entirely Australian in range. The enormous ears (whence "Rabbit" Bandicoot) distinguish this genus from _Perameles_. The pouch opens backwards, and there are eight mammae. _P. lagotis_, the only species about whose ways of life anything is {158} known, burrows in the soil, whence it extracts grubs; it is also a gra.s.s-feeder, and it is said that its likeness to a Rabbit in appearance is strengthened by its similarity in flavour!

_Perameles_ is a genus consisting of twelve species, which are found in Tasmania, Australia, and New Guinea. Like the last genus, from which it does not widely differ in other points, _Perameles_ consists of species which combine insectivorous and vegetarian habits. One species is said to become in captivity an expert in catching mice. The pouch opens backwards, and there are six or eight mammae.

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FIG. 87.--Pig-footed Bandicoot. _Ch.o.e.ropus castanotis._ 1/3.

The last genus of this family is _Ch.o.e.ropus_, containing but one species, _Ch. castanotis_. It is confined to the Australian continent. It is to be distinguished from the last two by the fact that there are only two functional digits, the second and third, in the fore-limb; the fourth is rudimentary; the other two are absent. It burrows, and is omnivorous like its allies. The two metacarpals that are developed are very long and closely apposed; they have hence a remarkably pig-like aspect, and justify its name. The pouch opens backwards, and there are eight mammae.

FAM. 4. NOTORYCTIDAE.--This family contains but a single genus and species, the recently-discovered _Notoryctes typhlops_.[97]

{159} We may regard as family-characters the pentadactyle limbs, the existence of three pairs of incisors in the lower and four in the upper jaw; and the tritubercular nature of the upper molars. _Notoryctes typhlops_, the "Marsupial Mole" as it has been termed, was originally discovered by Professor Stirling in Central South Australia. It is a burrowing creature, clothed in a silky fur of a pale golden red, without external ears. It has been compared in appearance with _Chrysochloris_, the Cape Golden Mole, and the eminent palaeontologist, Professor Cope, has even insisted upon a real genetic affinity. Edentate affinities have also been suggested. But _Notoryctes_ has a small pouch opening backwards as in other Polyprotodonts,[98] and as it also possesses marsupial bones it must undoubtedly be referred to the Marsupialia. The animal shows many curious adaptations to its underground mode of life. Certain of the vertebrae in the neck and in the lumbar region are firmly welded together, giving of course a strength of push, and suggesting the Armadillos; the claws of the third and fourth front-toes are greatly enlarged, and must be efficient digging organs. The track of the animal is like that of a railway in mountainous country; it burrows for a short distance, emerges, and then descending beneath the surface re-emerges. The red colour of the fur is said to be in harmony with the arid soil in which it lives. The native name of the creature is "Urquamata." It feeds upon ants and other insects.

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FIG. 88.--Australian Marsupial Mole. _Notoryctes typhlops._ .

EXTINCT POLYPROTODONTS.--Of extinct Polyprotodonts (apart from those Mesozoic forms which are considered on p. 100) extinct species of _Thylacinus_ and _Dasyurus_ are known from {160} Australia. The most interesting fact in connexion with the Tertiary Polyprotodonts is the existence in South America of such genera as _Prothylacinus_ and _Amphiproviverra_, which are not merely Polyprotodonts but definitely Dasyures, and not referable to the Didelphyidae.

These forms have been included in an order, SPARa.s.sODONTA. But it is not by any means certain whether these forms are rightly placed in the neighbourhood of the carnivorous Marsupials; it is possible that they ought to be relegated to the Creodonta or to their allies. Their structure is in fact somewhat intermediate between those two groups. The teeth seem to be carnivorous and Marsupial-like in form; but as already mentioned, in connexion with the general structure of teeth, more than a single premolar is replaced. These animals in fact, in so far as regards their teeth, are midway between the Marsupials and the typical Eutheria. The angle of the lower jaw is inflected, but the palate is not marked by deficient ossification. At least this is not the case with all the members of the group. Whether the small _Microbiotherium_, which is made the type of a family, is rightly referred here is not certain. This animal had palatine vacuities as well as an inflected angle to the lower jaw.