MAMMALIA--_continued_.
We come now to animals less familiar to you, and none of which inhabit
Europe. We shall therefore pass more quickly over them.
ORDER 9. _Marsupialia (pouched)_.
_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials
are distinguished from other animals by a pouch which the mother has
under her belly, and in which the little ones take refuge at the
slightest alarm. You would be very much interested with their whole
story; but it has nothing to do with our present subject, which we
should soon lose sight of if we once began to wander away. This order,
so easily distinguished otherwise by that singular pouch, unfortunately
for us, offers nothing new for observation. It includes several species,
differing entirely from one another on the subject of nutrition, and
closely resembling some already described. Some are both carnivorous
and insectivorous, and are therefore armed with powerful canines, and
with molars like those of the hedgehog. Others are herbivorous, like
hares, and have almost the jaws of a rodent. Among the former we have
the opossum, celebrated by Florian in one of his prettiest fables. The
opossum inhabits South America. Charming little marsupials are to be
found in the Molucca Isles, whence come the nutmeg and the clove; these
are very like our squirrels, and live as they do, in trees, hunting
after fruit and insects. But the greatest number of marsupials belong
to Australia, the real native land of the order. They form by far the
larger portion of the mammalia with which that country is enriched;
the most celebrated amongst them being the kangaroo; an animal which
is now becoming common in European menageries, and which, excepting
in the matter of its pouch, is nothing but a magnified rabbit, as tall
as a man, and with a tail almost as long as itself. As a rabbit, you
know what its eating apparatus must be; and some day, no doubt, the
French Acclimatisation Society will enable us to judge of its flavor.
It is a kind of meat very likely to be seen on our dinner-tables
by-and-by; and, as you have plenty of time before you, probably you
may eat of it before you die.
ORDER 10. _Edentata (toothless)_.
These come more directly within our limits. They are classed according
to their teeth; yet if their name were to be trusted, they ought to
have no teeth at all. Whereas, alas! almost all of them have some, and
I am heartily ashamed of their scientific designation; but how can we
help it? The only really _Edentata, i. e_. toothless animals, amongst
them are the ant-eaters, who, considering the nature of their food, are
not much in want of teeth. They feed among the ant-hills, whence they
get their name; and as they are a tolerable size (from two to three feet
in length), it would really have been quite a hardship upon them to have
been forced to crunch the ants one by one at every meal. To get on
rapidly they catch them with their tongue; but what a tongue! Imagine a
kind of long earthworm, lodged in a snout which is elongated like a
bird's beak, and has a very small opening at the extremity. The ant
eater inserts this long, string-like tongue into the crowded ranks of
its victims, and, as its surface is glutinous, they stick to it by
hundreds at a time, and are swallowed at one gulp without a chance of
escape. This tongue, perfectly unique in its character, stretches out in
its murderous exertions to nearly three times the length of the animal's
long head. What a distance there seems between such a tongue as this and
your own little doorkeeper! But no wonder: we have now reached the
confines of the kingdom of _Mammalia,_ and the face of nature is
beginning to change.
The Armadillo, for instance, which comes next to the ant-eater, looks
far more like the tortoise or lizard than its noble mammalian brethren.
It is covered with scales; and, to look at it, you would say it was
a reptile, in spite of its higher internal organization. As for teeth,
it has certainly enough of them to give the lie to its name of
_edentata;_ but they are not very serviceable ones. They are called
molars, however, because they are situated in that part of the mouth
which is always assigned to molars; but they are miserable grindstones,
very unlike any of which we have hitherto treated. They are all of them
flattened cylinders, with no enamel bars to strengthen them; are small
and poor, and are placed at rather wide intervals from one another. The
poor armadillo munches with these, as best he can, slugs, tender roots,
and other prey of the same sort, with which he is obliged to content
himself, and which do not require very formidable tools.
The most questionable member of this class is the Unau, or Two-toed
Sloth. It only wants incisors to be as toothless as ourselves! and the
first time I saw it I took it for a little bear. It is true I was then
younger than you are now; for the bear, who is one of our nearest
neighbors, ought not to have been confounded with the unhappy being
before us, one of the drudges of the animal creation; though M. de
Blainville (who had not my excuse) proposed placing it still nearer
to us, namely, amongst the _Quadrumana_. Observe that instead of hands
it has at the end of its fore-limbs only two enormously curved claws,
which have somewhat the appearance of a gigantic fork accidentally
twisted. Accordingly its illustrious sponsor offered it to the world as
an _irregular quadrumane_. I believe so, indeed! This _quadrumane_
without hands--this _edentate_ whose molars are preceded by magnificent
canines--this enigma of nature, created for the confusion and despair of
all classification--does, I must in all humility confess, completely
upset the rule I laid down so stringently when speaking of the horse, as
to the objects for which canine teeth were framed. The canine teeth of
the sloth are more developed than its molars, and yet I cannot tell you
what they are there for at all. It feeds upon the leaves of trees; and
old travellers in South America, where it inhabits, have told us that,
when it has once hoisted itself up a tree, it will strip it to its last
leaf, and afterwards drop to the ground to avoid the trouble of crawling
down. This was what first obtained for it the villanous name of sloth, a
title which is certainly justified by its gait when on the ground; for
it is so ill-made that it cannot stand upright on its legs, but moves
clumsily forward by dragging itself on its elbows. It seems, however,
that when once in a tree it is a different creature altogether, and
can scramble lightly from branch to branch. Moreover, if its claws
cannot reasonably be reckoned as hands, they are at all events excellent
hooks; and when it is springing about thus in the forest, suspended
to the branches by its long arms, one might be tempted, while watching
it from below, to decide in favor of M. de Blainville's opinion. I saw
it originally myself in a cage.
As to the sloth's relationship to the armadillo, this rests upon a
detail which bears directly upon our subject. The molars in both animals
are cylindrical and smooth, this is a trifle, but what would you have?
The animal had to be classed somehow; since naturalists have not had
the wit to make detached companies, as they do in regiments of soldiers.
ORDER 11. _Amphibia (two-lived)_.
We are going farther and farther away. Here are animals who are nearly
half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have
two lives: one in the water, which is their true life, and where they
are in their element; the other upon land, where they can only crawl;
for their paws, which are but half developed, are destined to perform
the office of fins, and the hinder ones are extended flatly behind them,
and act like a fish's tail. They are divided into two families, the seal
and the walrus. The first feed on fish, and have the same internal
organization as the _Carnivora_, as well as the same dental
conformation. Some species have even exactly thirty-two teeth, as we
have. The jaw of the walrus is the least regular, and the incisors are
generally wanting, especially in the full-grown animal; for it appears
they lose them very young, as you lost your milk teeth, only, unluckily
for the walrus, his never grow again. On the other hand, he has two
canines in his upper jaw, which, next to the elephant's tusks, are the
largest we have yet met with. They are sometimes as much as two feet
long, and incline downwards with a curve, like the two bars of a
pick-axe. They would play the walrus the same trick that the incisors of
rodents are apt to do when they have not work enough to wear them down;
that is, stop up the entrance of its mouth, were it not that the lower
jaw is contracted in front, in order to fit into the space between the
two canines, which thus form a sort of passage in which it manoeuvres
freely. As you may suppose, the walrus cannot insert prey of any great
size into this contracted passage; but that is no matter, as he lives
partly on seaweeds, and partly--indeed principally--on shell-fish; his
molars being specially adapted for breaking shells. They are short
massive cylinders--the upper ones fitting into the lower as a pestle
into a mortar.
After the walrus comes a strange animal which has been ranked among
Cetaceans (we shall see why presently), but which it would be better
not to separate from the Amphibians, since an Amphibian order has been
made, for it crawls from time to time upon land: this is the Manatee,
or Sea-cow. It comes still nearer a fish than the others. Its forelimbs
are absolute fins, with mere vestiges of nails at their edges; it has
no hind ones, and its body, which is quite cylindrical, ends in a fin
tail in the shape of a shovel. The sea-cow feeds on plants and herbage,
and lives at the mouths of great rivers, going up them occasionally
to great distances, their banks serving it for pasture ground. In some
respects it is half brother to the hippopotamus and the great grass
eating _Pachydermata_, to whom it comes so near in internal
organization, and above all in the structure of its molars, that M.
de Blainville seriously proposed ranking it among the elephants, though
as an _irregular elephant_, as you may suppose. But then Cuvier
had even placed the seal among the _Carnivora_, by the side of
the cat, whose whiskers it possessed, and of the dog, whom it resembled
in the formation of its head. A naturalist's office is sometimes very
perplexing, I assure you; and as we are touching on this subject, I
cannot resist telling you that the sea-cow laid claim to, on so many
sides, had by right a free admission to the celebrated order of
_Primates_, although it looks exactly like a large barrel elongated
at the two ends. It suckles its young at the breast like man and the
monkey; and if Linnæus flinched from this rather too absurd parentage,
old navigators were less scrupulous. Observing this creature in the
distance, sporting on the waves, the upper part of its body quite out
of the sea, the sailors, whose eye is not of the most refined, and who
have no objections generally to the marvellous, imagined they saw a
new species of human beings; and hence arose those stories of mermaids
and sirens which have been told from the days of Homer downwards, and
the traditions of which have not yet quite died out in seaport towns.
To have been passed from man to the whale, touching the elephant on
the road, is a long way to travel, especially when, after all, one is
only a huge barrel of amphibious fat; and you may judge from this that
it is not always an easy thing to classify animals.
ORDER 12. _Cetacea (whale-kind)_.
Cetaceans are whales; and if I had been consulted on the matter, I
should have joined this order and the last together, under whatever
name was thought most appropriate. The passage from the seal to the
whale through the walrus and the sea-cow is an easy and natural one,
the two latter being obviously the connecting links; and in spite of
certain diversities of food, they form in reality one family-party,
as do the marsupials.
But it is too late in the day to talk of this, my dear child, and you
and I cannot pretend to alter what is taught in the schools.
But you are astonished, are you not? to hear that the whale is not a
fish: and no wonder. It is with it, however, as with the armadillo;
it is a fish with a higher organisation inside. The interior of this
enormous mass is a faithful reproduction, as a whole, of that of the
shrew-mouse; and when we come to talk of fishes you will have some
faint idea of the prodigious distance which this places between the
whale and his countrymen of the ocean.
As far as we are concerned, the chief difference is in their way of
breathing. The cetaceans breathe like ourselves, and are obliged to
come to the surface of the water to take air; while fishes have a
special apparatus, which I will explain to you presently, which enables
them to breathe in the water. This is a disadvantage to the cetacean
in his fish life; nevertheless, of all the mammals (as may easily be
imagined) he is the one who can remain longest under the water. With
us, for instance, the best divers one ever heard of, those who go to
the bottom of the sea after the pearl-oyster, can scarcely stay below
longer than two minutes; and even during that short time the veins of
the head become so overcharged with the blood, which cannot return to
the lungs owing to its forced inactivity, that when the diver comes
back to the surface it is by no means unusual to see him streaming
with blood from both nose and ears. The cetaceans remain under water
for half an hour at a time without seeming to suffer in the least; and
Breschet, a clever French naturalist, has given a very satisfactory
explanation of this wonderful faculty. In dissecting a cetacean, he
discovered all along the vertebral column an extensive network of large
veins, which are not found in other mammals, and which seemed designed
to serve as a refuge place for the blood during the time the animal
remains submerged. According to him, this network would act as a
reservoir, to which any overplus in the head or important organs would
flow through vessels communicating therewith, and which might swell
out as it pleased, without any risk to the inert bed of fat against
which it lies. From thence the blood rushes to the lungs, as soon as
the animal's return to the air enables them to play as usual. It must
be admitted, at the same time, that all this involves the necessity
of a much less active life than that of land mammals, that is to say,
a consumption of oxygen much smaller in proportion than theirs; for
were you to be furnished down your back with the finest network
reservoir in the world for venous blood, it would still not enable you
to remain half an hour without breathing.
There is nothing remarkable in the digestive apparatus of the cetaceans
except about the mouth, which is, as you know, the essentially variable
point among animals. To begin with, the cetacean tongue has the most
original appearance possible. Indeed, it is not a tongue, but a large
carpet, spread over the floor of the animal's mouth, and bears not the
faintest trace of resemblance to that nimble delicate porter, who does
you such good service. Imagine a thick soft lump absolutely crammed
with fat, and completely immovable, because it is glued down along its
whole length to the bottom of the mouth, and you will have a good idea
of this strange tongue, which in the whale, the largest of the
cetaceans, attains to the length of twenty-five feet and the width of
twelve, and of itself alone furnishes the whale-fishers with from five
to six tons of oil. This is a great deal farther from us than even the
long string which serves as a tongue to the ant-eater; and you feel
at once that we are getting among strangers.
With respect to teeth, I have now a melancholy piece of news to tell
you. We have done with them; we have seen the last of incisors, canines,
and molars, henceforth you will hear no more about those valuable
instruments. The teeth of the cetaceans, with whom this painful
falling-off begins, are no more teeth than his tongue is a tongue.
They are like so many nails set in a row in the jaw, and can only be
of use in retaining prey, not in grinding it; so that of the many
processes your bit of bread has to go through before it becomes a part
of yourself, there is one which is dispensed with here altogether,
namely, mastication. Cetaceans swallow their food without chewing it.
Besides, they have not got a whole set even of these unmasticating
teeth. Dolphins and porpoises, those faithful companions of the sailor,
around whose vessel they come playing and tumbling in the seas of all
countries, are the only ones who have them in both jaws. And these are
the small fry of the order; they do not usually exceed six or ten feet
in length.
The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals
the true whale in size, and whose head alone forms nearly the half of
its body, has teeth in the lower jaw only. This lower jaw, whose two
sides are joined together for half their length (a new deviation, very
unlike anything we have found before), is so little proportioned to
the gigantic head which contains it, that it is almost lost to sight,
and seems like a small plank slipped under a great square block.
Such as it is, however, it possesses many very respectable teeth, of
which some weigh as much as two pounds; and with these the cachalot,
whose ferocity is tremendous, tears in pieces everything that comes
near it, sometimes even the boats of the fishermen who risk their lives
in the dangerous pursuit of capturing them. By a singular arrangement,
of which this is the only known instance, there is, opposite each of
the cachalot's teeth, a corresponding cavity in the upper jaw, into
which they fit closely, turning the monster's muzzle into the most
formidable pair of pincers to be found in the animal kingdom. Another
curiosity in the order is the tooth of the Narwhal, a modest cetacean,
who is not much more than twenty feet long!
I speak of _the tooth_, because the creature has commonly but
one; a cylindrical-pointed tooth, spirally furrowed, whose length
varies from six to ten feet, and which comes straight out from the
extreme front of the upper jaw, like a soldier's pike. There are two
sockets at this extremity of the jaw, each furnished with a tooth-germ;
but as a general rule the germ on the left side is the only one which
develops, the other lying asleep in its socket, where it is choked up
and never appears. Behind this long pike, which, like the tusk of the
elephant, attracts to itself all the ivory in the body, lies a
completely unfurnished mouth; so that the owner of this magnificent
weapon, invaluable as a war-tool, but quite inapplicable to the purpose
of supporting life, is obliged to feed on small fishes and
_mollusks_. We have not yet spoken about these latter, but if you
have ever seen slugs and snails you will know what a _mollusk_ is.
The same wretched food falls to the lot of the whale also, that giant
of the ocean, whose open mouth forms an aperture twenty feet in extent.
Geoffroy St. Hilaire, in his indefatigable endeavors to trace out
points of resemblance connecting together animals the most unlike in
outward appearance, discovered, along the lower jaw of a young whale,
certain traces of teeth, indicating a last effort on the part of nature
to carry out her usual plan in furnishing the jaws of mammals; but,
like the right-hand tooth of the narwhal, these vain attempts soon
disappear, overgrown and lost in the tissue of the bone, so that the
whale offers us a true type of an _edentate_, classable with the
ant-eater, if one dared, and some people have dared, which by this
time will not surprise you. A classifying professor is utterly
merciless, whether he gets hold of the poor beasts by the mouth or by
the paw: they may protest with all the rest of their body against the
peg on which they are hung; so much the worse for them! If one were
to listen to what they have all got to say, it would be impossible to
classify even one.
To return to the whale. As a compensation for the teeth which she found
herself unable to give him, nature has manufactured on the two sides
of his upper jaw the most extraordinary apparatus without exception
to be found in the mammal mouth. You know what is called the
_whalebone_ used in stay-making, &c. The name is quite correct;
for those little flexible black strips, which support the figure so
nicely, began life in wandering over the polar or Australasian seas,
fastened to the palate of some monstrous whale.
On the two sides of the upper jaw the membrane which covers the palate
sends out rows of broad, thin, horny plates, which are from eight to
ten feet long (they have sometimes been seen twenty-five feet) in the
centre of each side, but which decrease gradually towards the
extremities. These are plates of whalebone (sometimes called whale's
whiskers), and the industry of man has turned them to a thousand
different uses; and you will open your eyes in astonishment when I
tell you that 800 or 900 of them have been sometimes counted on each
side of one mouth. Think of the number of stays that could be furnished
from the whalebone plates of one whale! It is true, they were not
exactly designed for this purpose originally. At the tips and on the
edges of these plates, the elastic fibres of which they are composed
unravel and peel off, and hang down from the lip like tufts of
horsehair. The Arctic seas, which the whale inhabits, are, like other
seas, full of innumerable troops of various little sea-animals, and
it is these which are destined to the honor of nourishing this gigantic
mass of flesh. When the colossus wishes to take a meal, he stretches
his mouth to its utmost width, and the salt water rushing in as into
a gulf, carries with it the imprudent little fry, who disappear then
and there for ever, being retained by the fringe-like sieve of the
whalebone. But as, in this way of eating, the stomach of the whale,
however large, would be terribly overgorged with water, he is furnished
with another apparatus for preventing the inconvenience. All the
superfluous water is rejected by the _pharynx_, and springs up
in spouts of fifteen or twenty feet high, through the nostrils,
_i.e._ the nasal openings, sometimes called "vents," sometimes
"blow-holes," which are pierced exactly at the top of the head. This
is a peculiarity common to all cetaceans, who have thence received the
name of "blowers," alluding to the powerful blast which is necessary
to send those majestic columns of water into the air; but it takes a
much milder form with the lesser cetaceans, such as dolphins and
porpoises. There is but a slight jet with them: the water escapes
comparatively quite quietly from the nostril-vents, trickling away
down the animal's sides.
I hope you consider that I have told you something new this time, my
dear child, and that our machine is beginning to change its appearance
very materially. I told you before that we had reached the outskirts
of the mammal kingdom. When we got to the armadillo we were within a
stone's throw of the reptiles, and here, one step more would take us
to the fishes. But we must first consider the birds, who are a very
superior set of animals to either of the latter; and we have accordingly
an order of mammals (Monotremes) which, as you will now find, opens
the road on that side also.
There are but two sorts, and both of them are natives of Australia,
which is, as you may have heard, the land of the wonderful in natural
history, and their existence was unknown to the learned men of Europe
till within the last sixty years. The most extraordinary of the two
is the _Ornithorhynchus_, or, to translate the hard Greek word
into English, the _Duck-bill_. Its mouth is a true duck's bill,
a downright horny beak, and its short paws sprawling sideways with a
membrane joining the toes together below, and coming a good deal beyond
them in front, seem intermediate between the flippers of the seal and
the webbed feet of a water-bird. The first naturalist who had anything
to do with the ornithorhynchus, Blumenbach the German, who gave it its
pretty name, did not think it was able to suckle its young, so much
did it differ from mammals in some respects, though looking so like
them on the whole. And presently a report arose in the learned world
that the new animal which had been classed at all risks among mammals
(it having the close fur and almost the body of the otter), a report
arose, I say, that this ornithorhynchus of Blumenbach laid eggs like
a real duck. The uproar in the Academies was tremendous. As early as
1829, indeed, a learned Englishman, Sir Everard Home had sent over to
France an authenticated drawing, as he said, of an ornithorhynchian
egg, to the delight of the hunters after analogies among animal races;
while Cuvier looked sadly askance at the intruder, whose arrival threw
his animal outlines into confusion, there being no place in them for
such a beast. Happily for the poor animal, he has ended by almost
settling the matter for himself. The ornithorhynchian egg has never
turned up. But in the animal's nest have been found baby
ornithorhynchuses, newly born, under two inches long (the full-grown
animal being more than a foot and a half), and not a trace of eggshells
near. Further investigations showed that the mother ornithorhynchus
nursed her young with milk, for curdled milk was found in their
stomachs; so the Australian phenomenon has been restored triumphantly
to the Mammalian order, whence Geoffroy St. Hilaire had excluded both
it and its companion, the _echidna_, a sort of hedgehog, provided
like the ornithorhynchus with a bird-like bill, only more of the
canary-bird sort; and like it, also, approximating to the bird tribe
by other details which do not belong to our subject. And so the matter
stands at present; and all we venture to say is that classification
had a very lucky escape.
And now, my dear child, that I have made you acquainted in detail with
your nearest neighbors, the last of whom, nevertheless, are strangely
unlike you outside, however they may resemble you within, I shall take
the liberty of going more quickly over the ground, and shall point out
in the mass only the more important changes which lead from one class
of animals to another. I should be found fault with if I tried to make
you too learned, and you yourself might be tempted to tell me, to my
sorrow, that you had heard about enough.