St. George Jackson Mivart

“ Among the characters which serve to distinguish the marsupials, there are two to which I have already called attention in describing the kangaroo; namely, the marsupial bones and the inflected angle of the lower jaw.
Every mammal which has marsupial bones has the angle of its jaw inflected, or else has no angle to its jaw at all; while every animal which has both marsupial bones and an inflected jaw-angle possesses also those special characters of the reproductive system which distinguish the marsupials from all other mammals. ”

“ Man's own class, Mammalia, is divisible into some dozen orders, and all the bats form one such order (Cheiroptera) , into which no animal but a bat is admitted. The characters of this order are the possession of a truly flying membrane, sustained by very elongated fingers; and the bat is capable of being very shortly defined, namely, as a truly flying mammal.
Bats present no real resemblance whatever to birds, but are, of course, much more like ourselves (who are their class-fellows) than they are like any bird. ”

“ All who have ever examined a bat closely, and observed its fur, ears, and teeth, must, I think, have recognized it as a kind of beast. Its real affinities, however, serve excellently well to demonstrate how little mere external aspect can be trusted as a guide to fundamental relationship. ”

“ As to our third point—the geological relations of the kangaroo—we may say, then, that "the kangaroo is one of an order of animals which ranged over the Northern Hemisphere in triassic and oolitic times, one exceptional family lingering in Europe to the Eocene period, and in America to the present day. That the kangaroo itself is a form certainly become fossil in its own region, where, in times geologically recent, creatures allied to it, but of vastly greater bulk, frequented the Australian plains." ”

“ To find living, in a state of nature, any member of the kangaroo's order, we must at least cross the Atlantic.
When America was discovered by the Spaniards, among the animals found there, and afterward brought over to Europe, were opossums, properly so called—marsupials, of the family Didelphidæ, which extend over the American Continent, from the United States to the far South. These creatures were the first to make known to Europeans [4] that habit of sheltering the young in a pouch which exists in the kangaroo, and which habit has given the name Marsupialia to the whole order. ”

“ Existing reptiles, then, present us with no close resemblance to bat-structure; but when we come to extinct reptiles—reptiles which flourished during and anterior to the deposition of our chalk-cliffs—the secondary or mesozoic period—we there find reptiles to have existed which present the most striking analogies with existing bats in all that regards their modes of locomotion, and their structure as far as it is related to such modes of locomotion. ”

“ The flight of the bat compared with that of most birds is excessively fluttering; but it is a true and perfect flight, and therefore very different from the analogous action of other beasts called "flying," such as the flying-squirrels, the flying-opossums, and the flying-lemur. In these animals the skin of the flanks can indeed be extended outward to the arm and the leg, and when so stretched (as when these animals take long jumps) seems as a sort of parachute to sustain them somewhat in the air, and so far break their fall as to enable them to flit from one bough to another ”

“ Having now learned something of the structure, habits, and history of the kangaroo, we may proceed to consider its zoölogical, geographical, and geological relations, in order to arrive at the best answer we may to our initial question, "What is a kangaroo?" ”

“ The bat is essentially an animal of the air—all its structure is modified for flight, and it rarely descends to the surface of the ground. The mole, on the contrary, is essentially an animal of the earth—all its structure is modified for burrowing, and it rarely ascends to the surface of the ground. The contrast could hardly be more complete, and yet the bat and the mole are cousins—the mole, the hedgehog, and the shrew-mouse, belonging to a group of beasts with which the bats show no inconsiderable affinity. ”

“ The kangaroo browses on the herbage and bushes of more or less open country, and, when feeding, commonly applies its front-limbs to the ground. It readily, however, raises itself on its hind-limbs and strong tail (as on a tripod) when any sound, sight, or smell, alarms its natural timidity (Fig. 1) . ”

“ But we cannot do so as regards the bat, because up to the present time no fossil remains whatever have been found which connect bats with other creatures. Moreover, the development of the bat's wing, difficult as it is to conceive upon any view of evolution, seems to me to be especially difficult as the mere result of the survival of the fittest, when we consider the origin of the initial stages of the organ. ”

“ Now, our bat has not got such a mass of muscle on each side of the keel of its breastbone as has the bird, and for a very good reason. In the bat, as in ourselves, the muscles which antagonize those just noticed (and which draw the arms away from the breast) are situated in the back; but, in the bird, both the muscles which strike the wings downward, and those which raise them upward, are together placed upon the breast, and hence its much deeper and more conspicuous keel. ”

“ But in kangaroos we have animals requiring to use their front pair of limbs for the purposes of more or less delicate manipulation with respect to the economy of the "pouch." Accordingly, for such creatures to be able to inhabit such a country, the hind pair of limbs must by themselves be fitted alone to answer the purpose of both the front and hind limbs of deer and antelopes. It would seem, then, that the peculiar structure of the kangaroo's limbs is of the greatest utility to it ”

“ We must wait patiently for more light from paleontology. But we may wait very hopefully. We may do so because the wonderfully rich harvest of fossil remains now being gathered in North America supplies us with good and solid ground for hope. ”

“ The part connecting the legs with the tail is called the interfemoral membrane.
Looking more closely, however, we find that, though the four fingers of each hand are thus bound together, the thumb is free, standing out at a wide angle, and furnished with a very long and strong-hooked claw. Of the four fingers, it is only the first which is clawed.
The uses made by the bat of its singularly-formed limbs are, of course, in exact correspondence with their structure. The fore-limbs are true organs of flight; the hind-limbs and tail have a rudder-like action. ”

“ Again, in the little jumping insectivorous mammal, the shrew (Macroscelides) , we meet with excessively long hind-limbs and a jumping habit. More than this: if we examine its teeth, we find both in the upper cutting teeth and in the back teeth great resemblance to those of the kangaroo. And yet there is no real affinity between the kangaroo and such creatures, any more than there is between a non-marsupial truly carnivorous beast and a marsupial carnivore. ”

“ This shield, which ordinarily stands up in front of the opening into the windpipe, bends back and comes over that opening just when food is passing, and so, at the right moment, almost always prevents food from "going the wrong way." But, in the young kangaroo, the milk being introduced, not by any voluntary act of the young kangaroo itself, but by the injecting action of its mother, it is evident that, did such a state of things obtain in it as has been just described, the result would be speedily fatal. ”

“ The flying-lemur is the best furnished in this respect, as it has not only a very extensive "alar membrane," but a short expansion of skin connects together not only the fingers but the toes also (which is not the case in bats) , and has a true interfemoral membrane extending from the hind-legs to the tail.
Fig. 3.—A Flying Frog.
There is no other such instance in beasts, or in any existing reptiles; but web-footedness is carried to such an extreme degree in a certain frog found in Borneo as to give rise to the conjecture that it was a flying animal. ”

“ Captain Cook continues, "as I was walking in the morning, at a little distance from the ship, I saw myself one of the animals which had been described; it was of a light mouse-color, and in size and shape very much resembling a greyhound; it had a long tail also, which it carried like a greyhound; and I should have taken it for a wild-dog if, instead of running, it had not leaped like a hare or deer." Mr. Banks also had an imperfect view of this animal, and was of opinion that its species was hitherto unknown. The work exhibits an excellent figure of the animal. ”

“ Bats are most widely diffused over the surface of the globe, as their powers of flight might lead us to expect. Even Australia—so very peculiar in the character of the other beasts which inhabit it—possesses bats belonging to both of the bat families which are found in our own island. ”

“ The oldest fossil bat yet known is represented by a few teeth found in Eocene deposits in Suffolk. The oldest perfect fossil bat is the Vespertilio Parisiensis of the gypsum-bed of Montmartre, near Paris.
Some forms of existing beasts, however, which are now distinct enough, such as the ox and the pig, or the tapir and the horse, were preceded in early Tertiary times by others which were more or less intermediate in structure. This is not the case as regards hats. Bats, as soon as they appear at all, appear as thoroughly and as perfectly organized bats as are those living among us now. ”

“ THE group of animals called "Bats" is one full of interest to those specially occupied with the study of animal structure—the anatomist, the physiologist, and the philosophical zoölogist. At the same time it must be confessed that bats are far from exciting that general interest which in fact they merit. ”

“ Such is the general structure of an adult kangaroo. At birth it is strangely different from what it ultimately becomes.
It is customary to speak of the human infant as exceptionally helpless at birth and after it, but it is at once capable of vigorous sucking, and very early learns to seek the nipple. The great kangaroo, standing some six feet high, is at birth scarcely more than an inch long, with delicate naked skin, and looking like part of an earthworm. But, in such feeble and imperfectly developed condition, the young-kangaroo cannot actively suck. ”

“ Now, in the first place, very noticeable is the much greater diversity of structure found in the kangaroo's order than in any other order of mammals. While each of the latter is of one predominate type of structure and habit, we have found in the marsupials the greatest diversity in both.
Some marsupials are, we have seen, arboreal, some are burrowing, some flit through the air, while others range over and graze upon grassy plains. Some feed on vegetable food only, others are as exclusively insectivorous or carnivorous, and their teeth vary much in number and structure. ”

“ No other known beast besides walks upon a single toe in each hind-foot, save the horse family (horses, asses, and zebras) , and they walk upon a different one, namely, that which answers to our middle-toe, while Chæropus walks on the next outer one or fourth. No known beast besides Chæropus walks upon two toes in each foot, save hoofed creatures, such as the ruminants and their allies; but in them it is the third and fourth toes that are used, while in Chæropus it is the second and third toes. ”

“ The kangaroo is said to be able to clear even more than fifteen feet at one bound.
Rapidity of locomotion is especially necessary for a large animal inhabiting a country subject to such severe and widely-extending droughts as in Australia. The herbivorous animals which people the plains of Southern Africa—the antelopes—are also capable of very rapid locomotion. In the antelopes, however, as in all hoofed beasts, all the four limbs (front as well as hind) are exclusively used for locomotion. ”

“ The bat exhibits to us the body of a beast, specially modified to live the life of a bird, and at the same time serves to give us a fair conception of certain ancient reptilian forms, the remains of which are found deeply buried in deposits made untold ages ago—in the secondary rocks. ”

“ Now, the whole group of flying-foxes is strictly confined to the tropical regions of the Old World and Australia. In the same way the family of leaf-nosed bats, like those of England—the Rhinolophidœ,—is limited to the Old World, though reaching there much higher latitudes than do the flying-foxes. ”

“ The kangaroo breeds freely in this country, producing one at a birth. We have young ones every year in our Zoölogical Gardens. A large number of them are reared to maturity, and altogether our kangaroos thrive and do well. One born in our gardens was lately in the habit of still entering the pouch of its mother, although itself bearing a very young one within its own pouch. ”

“ Another kind of bat found in England is called the leaf-nosed bat, because in it not the ear but the nose is the seat of extraordinary skin-development—productions of skin curiously folded surrounding and surmounting the external nostrils. ”

“ But relics of creatures more closely allied to the kangaroo existed in times ancient historically, though, geologically speaking, very recent. Just as in the recent deposits of South America we find the bones of huge beasts, first cousins to the sloths and armadilloeswhich live there now, so in Australia there lived beasts having the more essential structural characters of the kangaroo, yet of the bulk of the rhinoceros. ”

“ We have, then, in Australia what may be termed a triassic land, still showing us in life to-day the more or less modified representations of forms which elsewhere have long since passed away from among us, leaving but rare and scattered fragments—relics "sealed within the iron hills." ”

“ Remains of beasts more or less closely resembling some of those existing now in Australia are found low down in the secondary rocks, namely, in the Triassic and Oolitic formations. Generally speaking, however, beasts such as those which now exist are not found deeper than the Tertiary strata, and this is the case with bats. ”

“ As to its civilized hunters, the same author tells us that kangaroos are hunted by dogs which run entirely by sight, and partake of the nature of the greyhound and deerhound, and, from their great strength and fleetness, are so well adapted for the duties to which they are trained, that the escape of the kangaroo, when it occurs, is owing to peculiar and favorable circumstances ”