the parts of which mutually correspond, and concur in producing
the same definitive action, by a reciprocal reaction. None of
these parts can change in form, without the others also changing;
and consequently, each of them, taken separately, indicates and
ascertains all the others.
Thus, if the intestines of an animal are so organised as to be
fitted for the digestion of flesh only, and that flesh recent, it
is necessary that its jaws be so constructed as to fit them for
devouring live prey; its claws for seizing and tearing it; its teeth
for cutting and dividing it; the whole system of its organs of
motion, for pursuing and overtaking it; and its organs of sense for
discovering it at a distance. It is even requisite that nature have
placed in its brain the instinct necessary for teaching it to conceal
itself, and to lay snares for its victims.
Such are the general conditions which nature imposes upon the
structure of carnivorous animals; and which every animal of this
description must indispensably combine in its constitution, for
without them its race could not subsist. But subordinate to these
general conditions, there exist others, having relation to the size,
the species, and the haunts of the prey for which the animal is
adapted; and from each of these particular conditions, there result
modifications of detail in the forms which arise from the general
conditions. Thus not only the class, but the order, the genus, and
even the species, are found expressed in the form of each part.
In fact, in order that the jaw may be able to seize, it must have
a certain form of condyle; that the resistance, the moving power,
and the fulcrum, should have a certain relative position in regard
to each other; and that the temporal muscles should be of a certain
size; the hollow or depression, too, in which these muscles are
lodged, must have a certain depth; and the zygomatic arch, under
which they pass, must not only have a certain degree of convexity,
but it must be sufficiently strong to support the action of the
masseter.
In order that the animal may be able to carry off its prey, it must
have a certain degree of vigour in the muscles which elevate the
head; whence there results a determinate form in the vertebræ from
which these muscles take their rise, and in the occiput into which
they are inserted.
In order that the teeth may be able to cut flesh, they must be
sharp-edged, and must be so in a greater or less degree, according
as they have flesh more or less exclusively to cut. Their base will
be solid, according to the quantity and size of the bones which they
have to break. The whole of these circumstances must necessarily
influence the development and form of all the parts which contribute
to move the jaws.
In order that the paws may be able to seize the prey, there must be
a certain degree of mobility in the toes, and a certain degree of
strength in the claws, from which there will result determinate forms
in all the phalanges, and a corresponding distribution of muscles and
tendons. The fore-arm, or cubitus, must possess a certain facility
of turning, from which there will also result determinate forms in
the bones of which it is composed. But the bones of the cubitus
being articulated to the humerus, a change in the proportions of the
former, will necessarily induce a corresponding change in the latter.
The shoulder-bones must have a certain degree of firmness in such
animals as make use of their fore-legs for seizing, and from this
there must also result a certain peculiarity in their form. The play
of all these parts will require certain proportions in all their
muscles, and the impressions made by these muscles so proportioned,
will determine still more particularly the forms of the bones.
It is easy to see that similar conclusions may be drawn with regard
to the posterior extremities which contribute to the rapidity of
the general motions; with regard to the composition of the trunk,
and the forms of the vertebræ, which exert an influence upon the
facility and flexibility of these motions; and, lastly, with regard
to the forms of the bones of the nose, of the orbit, and of the
ear, the connection of which with the perfection of the senses of
smell, sight, and hearing, is evident. In a word, the form of the
tooth regulates the forms of the condyle, of the scapula, and of the
claws, in the same manner as the equation of a curve regulates all
its properties; and as, by taking each property separately for the
base of a particular equation, we find both the ordinary equation,
and all the other properties whatever; so, the claw, the scapula, the
condyle, the femur, and all the other bones taken separately, give
the tooth, or are reciprocally given by it; and thus, by commencing
with any one of these bones, a person who possesses an accurate
knowledge of the laws of organic economy, may reconstruct the whole
animal.
This principle seems sufficiently evident, in the general acceptation
in which it is here taken, and does not require any fuller
demonstration; but when it comes to be applied, there will be found
many cases where our theoretical knowledge of the relations of forms
will not be sufficient, unless it be supported by observation and
experience.
For example, we are well aware, that hoofed animals must all be
herbivorous, since they have no means of seizing prey. It is also
evident, that, having no other use to make of their fore-legs than
to support their body, they do not require a shoulder so vigorously
organised as that of carnivorous animals; they have, therefore, no
acromion or clavicle, and their shoulder-blades are narrow. Having
also no occasion to turn their fore-arm, their radius is united to
the ulna by ossification, or at least articulated by a ginglimus
or hinge-joint, and not by arthrodia or ball and socket, to the
humerus. Their food being herbaceous, will require teeth furnished
with flat surfaces, for bruising seeds and plants. The crown of the
teeth must also be unequal, and, for this purpose, must be composed
of parts alternately consisting of bone and of enamel. Teeth of
this structure necessarily require horizontal motions to enable
them to triturate the food; and hence the condyle of the jaw cannot
be so strictly confined within its articulating cavity as in the
carnivorous animals, but must be flattened, and thus correspond with
a more or less flattened surface of the temporal bones. Further, the
temporal fossa, which will only have a small muscle to contain, will
be narrower, and not so shallow, as that of carnivorous animals.
All these circumstances are deducible from each other, according to
their greater or less generality, and in such a manner, that some of
them are essential and exclusively peculiar to hoofed animals, while
others, although equally necessary in these animals, are not entirely
peculiar to them, but may occur in other animals also, where the rest
of the conditions will permit their existence.
If we proceed to consider the orders or subdivisions of the class of
hoofed animals, and examine what modifications the general conditions
undergo, or rather what particular conditions are conjoined with
them, according to the respective characters of these orders, the
reasons of these subordinate conditions begin to appear less obvious.
We can still easily conceive, in general, the necessity of a more
complicated system of digestive organs in those species which have
a more imperfect masticatory system; and hence we may presume, that
these latter must be rather ruminating animals, in which there is
wanting such or such an order of teeth; and may also deduce from the
same consideration, the necessity of a certain form of the œsophagus,
and of corresponding forms in the vertebræ of the neck, &c. But I
doubt whether it would have been discovered, independently of actual
observation, that the ruminating animals should all have cloven
hoofs, and that they should be the only animals having them; that
there should be horns on the fore-head in this class alone; or that
such of them as have sharp canine teeth, should, in general, have no
horns.
However, since these relations are constant, we may be assured that
they have a sufficient cause; but as we are not acquainted with that
cause, we must supply the defect of theory by means of observation,
and in this way establish empirical laws which become nearly as
certain as those deduced from rational principles, when founded
upon observations, the authenticity of which is proved by frequent
repetition. Hence, at the present day, any one who observes only the
print of a cloven foot, may conclude that the animal which left this
impression ruminates; and this conclusion is quite as certain as
any other in physics, or in moral philosophy. This simple footmark,
therefore, indicates at once to the observer the forms of the teeth,
of the jaws, of the vertebræ, of all the bones of the legs, thighs,
shoulders, and pelvis of the animal which had passed. It is a surer
mark than all those of Zadig. That there are secret reasons, however,
for all these relations, is what observation alone is sufficient to
shew, independently of any general principles of philosophy.
In fact, when we construct a table of these relations, we remark
not only a specific constancy, if the expression may be allowed,
between a particular form of a particular organ, and some other form
of a different organ; but we also perceive a classic constancy of
conformation, and a corresponding gradation, in the development of
these two organs, which demonstrate their mutual influence, almost as
well as the most perfect deduction of reason.
For example, the dentary system of the hoofed animals, which are not
ruminant, is in general more perfect than that of the cloven-footed
or ruminating animals, because the former have either incisors, or
canine teeth, and almost always both in each jaw; and the structure
of their foot is in general more complicated, because they have more
toes or claws, or their phalanges less enveloped in the hoof,--or a
greater number of distinct bones in the metacarpus and metatarsus--or
more numerous tarsal bones--or a fibula more distinct from the
tibia--or, lastly, that all these circumstances are often united in
the same species of animals.
It is impossible to assign reasons for these relations; but we are
certain that they are not the effects of chance, because, whenever a
cloven-footed animal manifests, in the arrangement of its teeth some
tendency to approach the animals we now speak of, it also manifests
a similar tendency in the arrangement of its feet. Thus the camels,
which have canine teeth, and even two or four incisors in the upper
jaw, have an additional bone in the tarsus, because their scaphoid
bone is not united to the cuboid, and they have very small hoofs,
with corresponding phalanges. The musk animals, whose canine teeth
are much developed, have a distinct fibula along the whole length
of their tibia; while the other cloven-footed animals have only, in
place of a fibula, a small bone articulated at the lower end of the
tibia. There is, therefore, a constant harmony between two organs
apparently having no connection; and the gradations of their forms
preserve an uninterrupted correspondence, even in those cases in
which we cannot account for their relations.
Now, by thus adopting the method of observation as a supplementary
means, when theory is no longer able to direct our views, we arrive
at astonishing results. The smallest articulating surface of bone, or
the smallest apophysis, has a determinate character, relative to the
class, the order, the genus, and the species to which it belonged;
insomuch, that when one possesses merely a well preserved extremity
of a bone, he can, by careful examination, and the aid of a tolerable
analogical knowledge, and of accurate comparison, determine all these
things with as much certainty as if he had the entire animal before
him. I have often made trial of this method upon portions of known
animals, before reposing full confidence upon it, in regard to fossil
remains; and it has always proved so completely satisfactory, that
I have no longer any doubts regarding the certainty of the results
which it has afforded me.
It is true, that I have enjoyed all the advantages which were
necessary for the undertaking; and that my favourable situation, in
the Museum of Natural History at Paris, and assiduous research for
nearly thirty years, have procured me skeletons of all the genera
and sub-genera of quadrupeds, and even of many species in some
genera, and of several varieties of some species. With such means,
it was easy for me to multiply my comparisons, and to verify in all
their details the applications which I have made of the various laws
deducible from such circumstances as have been stated.
We cannot here enter into a more lengthened detail of this method,
and must refer to the large work on Comparative Anatomy, in which all
its rules will be found. In the mean time, an intelligent reader may
gather a great number of these from the work upon Fossil Bones, if he
take the trouble of attending to all the applications of them which
we have there made. He will see, that it is by this method alone that
we are guided, and that it has almost always sufficed for referring
each bone to its species, when it was a living species--to its genus,
when it was an unknown species--to its order, when it was a new
genus--and to its class, when it belonged to an order not hitherto
established--and to assign it, in the three last cases, the proper
characters for distinguishing it from the nearest resembling orders,
genera, and species. Before the commencement of our researches,
naturalists had done no more than this with regard to animals, which
they had the opportunity of examining in their entire state. Yet, in
this manner, we have determined and classed the _remains_ of more
than a hundred and fifty mammiferous and oviparous quadrupeds.
_View of the General Results of these Researches._
Considered with regard to species, upwards of ninety of these animals
are most assuredly hitherto unknown to naturalists; eleven or twelve
have so perfect a resemblance to species already known, that the
slightest doubt cannot be entertained of their identity; the others
exhibit many traits of resemblance to known species, but their
comparison has not yet been made with sufficient precision to remove
all doubts.
Considered with regard to genera, of the ninety hitherto unknown
species, there are nearly sixty that belong to new genera. The other
species rank under genera or subgenera already known.
It may not be without use, also, to consider these animals with
regard to the classes and orders to which they belong. Of the hundred
and fifty species, about a fourth part are oviparous quadrupeds, and
all the rest mammifera. Of these last, more than the half belong to
non-ruminant hoofed animals.
Notwithstanding what has been done, it would still be premature to
establish upon these numbers any conclusion relative to the theory
of the earth, because they are not in sufficient proportion to the
numbers of genera and species which may be buried in the strata of
the earth. Hitherto the bones of the larger species have been chiefly
collected, these being more obvious to agricultural labourers; while
the bones of the smaller species are usually neglected, unless when
they chance to fall into the hands of a naturalist, or when some
particular circumstance, such as their excessive abundance in certain
places, attracts the attention even of the common people.
_Relations of the Species of Fossil Animals with the Strata in which
they are found._
The most important consideration, that which, in fact, is the chief
object of all my researches, and which establishes their legitimate
connection with the Theory of the Earth, is to ascertain in what
strata each species is found, and whether there may be some general
laws, relative either to the zoological subdivisions, or to the
greater or less resemblance of the species to those of the present
day.
The laws which have been recognised with respect to these relations
are very distinct and satisfactory.
In the first place, it is clearly ascertained that the oviparous
quadrupeds appear much more early than the viviparous; that they are
even more abundant, larger, and more varied, in the ancient strata
than at the surface of the globe, as it exists at present.
The Ichthyosauri, the Plesiosauri, several species of Tortoise, and
several species of Crocodile, are found beneath the chalk, in the
deposits commonly called _Jura formations_. The Monitors of Thuringia
would be still older, if, according to the Wernerian School, the
copper-slate in which they are contained, along with a great variety
of fishes supposed to have belonged to fresh-water, is to be placed
among the oldest beds of the secondary formations. The enormous
crocodiles and the great tortoises of Maestricht, are found in the
chalk formation itself; but these are marine animals.
This earliest appearance of fossil bones seems, therefore, already
to indicate, that dry lands and fresh waters had existed before the
formation of the chalk deposits. But neither at this period, nor
while the chalk was forming, nor even long after, have any bones of
land-mammifera been encrusted; or, at least, the small number of
these, which are alleged to have been found in strata of these dates,
forms but a trifling exception.
We begin to find bones of marine mammifera, namely, of lamantins and
seals, in the coarse shelly limestone which covers the chalk in the
neighbourhood of Paris; but there are still no bones of terrestrial
mammifera.
Notwithstanding the most assiduous investigation, I have not been
able to discover any distinct trace of this class in any of the
deposits preceding those which rest upon the coarse limestone.
Certain lignites and molasses do in fact contain them; but I am very
doubtful whether these deposits are all, as is commonly supposed,
anterior to that limestone. The places where these bones have
been found are so limited, both in extent and in number, as to
induce us to suppose some irregularity, or some repetition of the
formation containing them. On the contrary, the moment we arrive
at the deposits which rest upon the coarse limestone, the bones of
land-animals present themselves in great abundance.
As it is reasonable to believe that shells and fishes did not exist
at the period of the formation of primitive rocks, we are also led
to conclude that the oviparous quadrupeds began to exist along with
the fishes, and at the commencement of the period during which the
secondary rocks were formed; but that the land-quadrupeds did not
appear upon the earth, at least in any considerable number, till
long after, and until the coarse limestone strata, which contain the
greater number of our genera of shells, although of species different
from ours, had been deposited.
It is remarkable that those coarse limestone strata which are used
at Paris for building, are the last formed strata which indicate a
long and quiet continuance of the sea upon our continents. Above
them, indeed, there are found formations containing shells and other
marine productions; but these consist of collections of transported
matters, sand, marls, sandstones, and clays, which rather indicate
transportations that have taken place with more or less violence,
than strata formed by tranquil deposition; and, if there be some
rocky and regular strata of pretty considerable magnitude, beneath or
above these transported matters, they generally exhibit indications
of having been deposited from fresh water.
Almost all the known bones of viviparous quadrupeds, therefore, have
been found either in those fresh-water formations, or in the alluvial
formations; and consequently there is every reason to conclude that
these quadrupeds have only begun to exist, or, at least, to leave
their remains in the strata of our earth, after the last retreat of
the sea but one, and during the state of things that preceded its
last irruption.
But there is also an order in the disposition of these bones with
regard to each other; and this order further announces a very
remarkable succession in the appearance of the different species.
All the genera which are now unknown, the Palæotheria, Anaplotheria,
&c., with the position of which we are thoroughly acquainted, belong
to the oldest of the formations of which we are now speaking, those
which rest immediately upon the coarse limestone. It is chiefly these
genera which occupy the regular beds that have been deposited from
fresh-water, or certain alluvial beds of very ancient formation,
generally composed of sand and rolled pebbles, and which were perhaps
the earliest alluvium of that ancient world. Along with these there
are also found some lost species of known genera, but in small
numbers, and some oviparous quadrupeds and fishes, which appear to
have been all inhabitants of fresh-water. The beds which contain them
are always more or less covered by alluvial beds, containing shells,
and other marine productions.
The most celebrated of the unknown species, which belong to known
genera, or to genera closely allied to those which are known, such as
the fossil elephants, rhinoceroses, hippopotami, and mastodons, do
not occur along with those more ancient genera. It is in the alluvial
formations alone that they are discovered, sometimes accompanied
with marine shells, and sometimes with fresh-water shells, but never
in regular stony beds. Every thing that is found along with these
species is either unknown like themselves, or at least doubtful.
Lastly, the bones of species which are apparently the same as those
that are still found alive, are never discovered, except in the last
alluvial deposits formed on the sides of rivers, or on the bottoms
of ancient pools or marshes now dried up, or in the substance of beds
of peat, or in the fissures and caverns of some rocks; or, lastly, at
small depths below the surface, in places where they may have been
buried by the falling down of debris, or even by the hand of man; and
their superficial position renders these bones, although the most
recent of all, almost always the worst preserved.
It must not, however, be thought that this classification of the
various geological positions of fossil remains, is as certain as that
of the species, or that it is equally capable of demonstration. There
are numerous reasons which prevent this from being the case.
In the first place, all my determinations of species have been made
upon the bones themselves, or by means of good figures; whereas it
has been impossible for me personally to examine all the places in
which these bones have been discovered. I have very frequently been
obliged to content myself with vague and ambiguous accounts, given by
people who were not themselves well aware of what it was necessary to
observe; and, more frequently still, I have been unable to procure
any information whatever on the subject.