Lamarck's Theory of Progression illustrated.--Class of Facts which
give Color to it.--The Credulity of Unbelief.--M. Maillet and his
Fish-birds.--Gradation not Progress.--Geological Argument.--The
Present incomplete without the Past.--Intermediate Links of
Creation.--Organisms of the Lower Old lied Sandstone.--The
_Pterichthys_.--Its first Discovery.--Mr. Murchison's Decision
regarding it.--Confirmed by that of Agassiz.--Description.--The
several Varieties of the Fossil yet discovered.--Evidence of Violent
Death in the Attitudes in which they are found.--The _Coccosteus_
of the Lower Old Red.--Description.--Gradations from Crustacea to
Fishes.--Habits of the Coccosteus.--Scarcely any Conception too
extravagant for Nature to realize.
Mr. Lyell's brilliant and popular work, _The Principles of Geology_,
must have introduced to the knowledge of most of my readers the
strange theories of Lamarck. The ingenious foreigner, on the strength
of a few striking facts, which prove that, to a certain extent,
the instincts of species may be improved and heightened, and their
forms changed from a lower to a higher degree of adaptation to
their circumstances, has concluded that there is a natural progress
from the inferior orders of being towards the superior; and that
the offspring of creatures low in the scale in the present time,
may hold a much higher place in it, and belong to different and
nobler species, a few thousand years hence. The descendants of the
_ourang-outang_, for instance, may be employed in some future age in
writing treatises on Geology, in which they shall have to describe
the remains of the _quadrumana_ as belonging to an extinct order.
Lamarck himself, when bearing home in triumph with him the skeleton
of some huge salamander or crocodile of the Lias, might indulge,
consistently with his theory, in the pleasing belief that he had
possessed himself of the bones of his grandfather--a grandfather
removed, of course, to a remote degree of consanguinity, by the
intervention of a few hundred thousand _great-greats_. Never yet
was there a fancy so wild and extravagant but there have been men
bold enough to dignify it with the name of philosophy, and ingenious
enough to find reasons for the propriety of the name.
The setting-dog is _taught_ to set; he squats down and points at the
game; but the habit is an acquired one--a mere trick of education.
What, however, is merely acquired habit in the progenitor, is
found to pass into instinct in the descendant: the puppy of the
setting-dog squats down and sets _untaught_--the educational trick
of the parent is mysteriously transmuted into an original principle
in the offspring. The adaptation which takes place in the forms and
constitution of plants and animals, when placed in circumstances
different from their ordinary ones, is equally striking. The
woody plant of a warmer climate, when transplanted into a colder,
frequently exchanges its ligneous stem for a herbaceous one, as if
in anticipation of the killing frosts of winter; and, dying to the
ground at the close of autumn, shoots up again in spring. The dog,
transported from a temperate into a frigid region, exchanges his
covering of hair for a covering of wool; when brought back again to
his former habitat, the wool is displaced by the original hair. And
hence, and from similar instances, the derivation of an argument,
good so far as it goes, for changes in adaptation to altered
circumstances of the organization of plants and animals, and for the
unprovability of instinct. But it is easy driving a principle too
far. The elasticity of a common bow, and the strength of an ordinary
arm, are fully adequate to the transmission of an arrow from one
point of space to another point a hundred yards removed; but he would
be a philosopher worth looking at, who would assert that they were
equally adequate for the transmission of the same arrow from points
removed, not by a hundred yards, but by a hundred miles. And such,
but still more glaring, has been the error of Lamarck. Fie has argued
on this principle of improvement and adaptation--which, carry it as
far as we rationally may, still leaves the vegetable a vegetable, and
the dog a dog--that, in the vast course of ages, inferior have risen
into superior natures, and lower into higher races; that molluscs and
zoöphytes have passed into fish and reptiles, and fish and reptiles
into birds and quadrupeds; that unformed, gelatinous bodies, with an
organization scarcely traceable, have been metamorphosed into oaks
and cedars; and that monkeys and apes have been transformed into
human creatures, capable of understanding and admiring the theories
of Lamarck. Assuredly there is no lack of faith among infidels;
their "vaulting" credulity o'erleaps revelation, and "falls on the
other side." One of the first geological works I ever read was a
philosophical romance, entitled _Telliamed_, by a M. Maillet, an
ingenious Frenchman of the days of Louis XV. This Maillet was by
much too great a philosopher to credit the scriptural account of
Noah's flood; and yet he could believe, like Lamarck, that the whole
family of birds had existed at one time as fishes, which, on being
thrown ashore by the waves, had got feathers by accident; and that
men themselves are but the descendants of a tribe of sea-monsters,
who, tiring of their proper element, crawled up the beach one sunny
morning, and, taking a fancy to the land, forgot to return.[H]
[Footnote H: Few men could describe better than Maillet. His
extravagances are as amusing as those of a fairy tale, and quite as
extreme. Take the following extract as an instance:--
"Winged or flying fish, stimulated by the desire of prey, or the
fear of death, or pushed near the shore by the billows, have fallen
among reeds or herbage, whence it was not possible for them to resume
their flight to the sea, by means of which they had contracted
their first facility of flying. Then their fins, being no longer
bathed in the sea-water, were split, and became warped by their
dryness. While they found, among the reeds and herbage among which
they fell, any aliments to support them, the vessels of their fins,
being separated, were lengthened and clothed with beards, or, to
speak more justly, the membranes, which before kept them adherent
to each other, were metamorphosed. The beard formed of these warped
membranes was lengthened. The skin of these animals was insensibly
covered with a down of the same color with the skin, and this down
gradually increased. The little wings they had under their belly,
and which, like their wings, helped them to walk in the sea, became
feet, and served them to walk on land. There were also other small
changes in their figure. The beak and neck of some were lengthened,
and those of others shortened. The conformity, however, of the first
figure subsists in the whole, and it will be always easy to know it.
Examine all the species of fowls, large and small, even those of
the Indies, those which are tufted or not, those whose feathers are
reversed, such as we see at Damietta--that is to say, whose plumage
runs from the tail to the head--and you will find species of fish
quite similar, scaly or without scales. All species of parrots, whose
plumages are so different, the rarest and the most singular-marked
birds, are, conformable to fact, painted like them with black, brown,
gray, yellow, green, red, violet color, and those of gold and azure;
and all this precisely in the same parts where the plumages of those
birds are diversified in so curious a manner."--_Telliamed_, p. 224,
ed. 1750.]
"How easy," says this fanciful writer, "is it to conceive the change
of a winged fish, flying at times through the water, at times through
the air, into a bird flying always through the air!" It is a law of
nature, that the chain of being, from the lowest to the highest form
of life, should be, in some degree, a continuous chain; that the
various classes of existence should shade into one another, so that
it often proves a matter of no little difficulty to point out the
exact line of demarcation where one class or family ends, and another
class or family begins. The naturalist passes from the vegetable
to the animal tribes, scarcely aware, amid the perplexing forms of
intermediate existence, at what point he quits the precincts of the
one to enter on those of the other. All the animal families have, in
like manner, their connecting links; and it is chiefly out of these
that writers such as Lamarck and Maillet construct their system.
They confound gradation with progress. Geoffrey Hudson was a very
short man, and Goliath of Gath a very tall one, and the gradations
of the human stature lie between. But gradation is not progress; and
though we find full-grown men of five feet, five feet six inches, six
feet, and six feet and a half, the fact gives us no earnest whatever
that the race is rising in stature, and that at some future period
the average height of the human family will be somewhat between ten
and eleven feet. And equally unsolid is the argument, that from a
principle of gradation in races would deduce a principle of progress
in races. The tall man of six feet need entertain quite as little
hope of rising into eleven feet as the short man of five; nor has the
fish that occasionally flies any better chance of passing into a bird
than the fish that only swims.
Geology abounds with creatures of the intermediate class: there
are none of its links more numerous than its connecting links; and
hence its interest, as a field of speculation, to the assertors of
the transmutation of races. But there is a fatal incompleteness in
the evidence, that destroys its character as such. It supplies in
abundance those links of generic connection, which, as it were,
marry together dissimilar races; but it furnishes no genealogical
link to show that the existences of one race derive their lineage
from the existences of another. The scene shifts, as we pass from
formation to formation; we are introduced in each to a new _dramatis
personæ_; and there exist no such proofs of their being at once
different and yet the same, as those produced in the _Winter's Tale_,
to show that the grown shepherdess of the one scene is identical with
the exposed infant of the scene that went before. Nay, the reverse
is well nigh as strikingly the case, as if the grown shepherdess had
been introduced into the earlier scenes of the drama, and the child
into its concluding scenes.
The argument is a very simple one. Of all the vertebrata, fishes
rank lowest, and in geological history appear first. We find their
remains in the Upper and Lower Silurians, in the Lower, Middle,
and Upper Old Red Sandstone, in the Mountain Limestone, and in
the Coal Measures; and in the latter formation the first reptiles
appear. Fishes seem to have been the master existences of two great
systems, mayhap of three, ere the age of reptiles began. Now fishes
differ very much among themselves: some rank nearly as low as worms,
some nearly as high as reptiles; and if fish could have risen into
reptiles, and reptiles into mammalia, we would necessarily expect to
find lower orders of fish passing into higher, and taking precedence
of the higher in their appearance in point of time, just as in the
_Winter's Tale_ we see the infant preceding the adult. If such be
not the case--if fish made their first appearance, not in their
least perfect, but in their most perfect state--not in their nearest
approximation to the worm, but in their nearest approximation to
the reptile--there is no room for progression, and the argument
falls. Now it is a geological fact, that it is fish of the higher
orders that appear first on the stage, and that they are found to
occupy exactly the same level during the vast period represented by
five succeeding formations. There is no progression. If fish rose
into reptiles, it must have been by sudden transformation--it must
have been as if a man who had stood still for half a lifetime should
bestir himself all at once, and take seven leagues at a stride. There
is no getting rid of miracle in the case--there is no alternative
between creation and metamorphosis. The infidel substitutes
progression for Deity; Geology robs him of his god.
But no man who enters the geological field in quest of the wonderful,
need pass in pursuit of his object from the true to the fictitious.
Does the reader remember how, in Milton's sublime figure, the body
of Truth is represented as hewn in pieces, and her limbs scattered
over distant regions, and how her friends and disciples have to
go wandering all over the world in quest of them? There is surely
something very wonderful in the fact, that, in uniting the links
of the chain of creation into an unbroken whole, we have in like
manner to seek for them all along the scale of the geologist;--some
we discover among the tribes first annihilated--some among the
tribes that perished at a later period--some among the existences
of the passing time. We find the present incomplete without the
past--the recent without the extinct. There are marvellous analogies
which pervade the scheme of Providence, and unite, as it were,
its lower with its higher parts. The perfection of the works of
Deity is a perfection entire in its components; and yet these are
not contemporaneous, but successive: it is a perfection which
includes the dead as well as the living, and bears relation, in its
completeness, not to time, but to eternity.
We find the organisms of the Old Red Sandstone supplying an important
link, or, rather, series of links, in the ichthyological scale,
which are wanting in the present creation, and the absence of which
evidently occasions a wide gap between the two grand divisions
or series of fishes--the bony and the cartilaginous. Of this,
however, more anon. Of all the organisms of the system, one of the
most extraordinary, and the one in which Lamarck would have most
delighted, is the _Pterichthys_, or winged fish, an ichthyolite which
the writer had the pleasure of introducing to the acquaintance of
geologists nearly three years ago, but which he first laid open to
the light about seven years earlier. Had Lamarck been the discoverer,
he would unquestionably have held that he had caught a fish almost
in the act of wishing itself into a bird. There are wings which want
only feathers, a body which seems to have been as well adapted for
passing through the air as the water, and a tail by which to steer.
And yet there are none of the fossils of the Old Red Sandstone which
less resemble any thing that now exists than its _Pterichthys_. I
fain wish I could communicate to the reader the feeling with which I
contemplated my first-found specimen. It opened with a single blow
of the hammer; and there, on a ground of light-colored limestone,
lay the effigy of a creature fashioned apparently out of jet, with a
body covered with plates, two powerful looking arms, articulated at
the shoulders, a head as entirely lost in the trunk as that of the
ray or the sun-fish, and a long, angular tail. My first-formed idea
regarding it was, that I had discovered a connecting link between
the tortoise and the fish--the body much resembles that of a small
turtle; and why, I asked, if one formation gives us sauroid fishes,
may not another give us chelonian ones? or if in the Lias we find
the body of the lizard mounted on the paddles of the whale, why not
find in the Old Red Sandstone the body of the tortoise mounted in
a somewhat similar manner? The idea originated in error; but as it
was an error which not many naturalists could have corrected at the
time, it may be deemed an excusable one, more especially by such of
my readers as may have seen well-preserved specimens of the creature,
or who examine the subjoined prints. (Nos. I. and II.) I submitted
some of my specimens to Mr. Murchison, at a time when that gentleman
was engaged among the fossils of the Silurian System, and employed
on his great work, which has so largely served to extend geological
knowledge regarding those earlier periods in which animal life first
began. He was much interested in the discovery: it furnished the
geologist with additional data by which to regulate and construct
his calculations, and added a new and very singular link to the
chain of existence in its relation to human knowledge. Deferring to
Agassiz, as the highest authority, he yet anticipated the decision
of that naturalist regarding it, in almost every particular. I had
inquired, under the influence of my first impression, whether it
might not be considered as a sort of intermediate existence between
the fish and the chelonian. He stated, in reply, that he could
not deem it referrible to any family of reptiles; that, if not a
fish, it approached more closely to the Crustacea than to any other
class; and that he had little doubt Agassiz would pronounce it to
be an ichthyolite of that ancient order to which the _Cephalaspis_
belongs, and which seems to have formed a connecting link between
crustacea and fishes.[I] The specimens submitted to Mr. Murchison
were forwarded to Agassiz. They were much more imperfect than some
which I have since disinterred; and to restore the entire animal from
them would require powers such as those possessed by Cuvier in the
past age, and by the naturalist of Neufchatel in the present. Broken
as they were, however, Agassiz at once decided from them that the
creature must have been a fish.
[Footnote I: The aborigines of South. America deemed it wonderful
that the Europeans who first visited them should, without previous
concert, agree in reading after the same manner the same scrap of
manuscript, and in deriving the same piece of information from
it. The writer experienced on this occasion a somewhat similar
feeling. His specimens seemed written in a character cramp enough
to suggest those doubts regarding original meaning which lead to
various readings; but the geologist and the naturalist agreed in
perusing them after exactly the same fashion--the one in London, the
other in Neufchatel. Such instances give confidence in the findings
of science. The decision of Mr. Murchison I subjoin in his own
words--his numbers refer to various specimens of _Pterichthys_: "As
to your fossils 1, 2, 3, we know nothing of them here, (London,)
except that they remind me of the occipital fragments of some of
the Caithness fishes. I do not conceive they can be referrible to
any reptile; for, if not fishes, they more closely approach to
crustaceans than to any other class. I conceive, however, that
Agassiz will pronounce them to be fishes, which, together with the
curious genus _Cephalaspis_ of the Old Red Sandstone, form the
connecting links between crustaceans and fishes. Your specimens
remind one in several respects of the _Cephalaspis_."]
[Illustration: _PLATE I._]
I have placed one of the specimens before me. Imagine the figure
of a man rudely drawn in black on a gray ground, the head cut off
at the shoulders, the arms spread at full, as in the attitude of
swimming, the body rather long than otherwise, and narrowing from
the chest downwards, one of the legs cut away at the hip-joint, and
the other, as if to preserve the balance, placed directly under
the centre of the figure, which it seems to support. Such, at a
first glance, is the appearance of the fossil. The body was of very
considerable depth, perhaps little less deep proportionally from back
to breast than the body of the tortoise; the under part was flat;
the upper rose towards the centre into a roof-like ridge; and both
under and upper were covered with a strong armor of bony plates,
which, resembling more the plates of the tortoise than those of the
crustacean, received their accessions of growth at the edges or
sutures. The plates on the under side are divided by two lines of
suture, which run, the one longitudinally through the centre of the
body, the other transversely, also through the centre; and they would
cut one another at right angles, were there not a lozenge-shaped
plate inserted at the point where they would otherwise meet. There
are thus five plates on the lower or belly part of the animal. They
are all thickly tubercled outside with wart-like prominences, (see
Plate I., fig. 4;) the inner present appearances indicative of
a bony structure. The plates on the upper side are more numerous
and more difficult to describe, just as it would be difficult to
describe the forms of the various stones which compose the ribbed
and pointed roof of a Gothic cathedral, the arched ridge or hump of
the back requiring, in a somewhat similar way, a peculiar form and
arrangement of plates. The apex of the ridge is covered by a strong
hexagonal plate, fitted upon it like a cap or helmet, and which
nearly corresponds in place to the flat central plate of the under
side. There runs around it a border of variously formed plates, that
diminish in size and increase in number towards the head, and which
are separated, like the pieces of a dissected map, by deep sutures.
They all present the tubercled surface. The eyes are placed in
front, on a prominence considerably lower than the roof-like ridge
of the back; the mouth seems to have opened, as in many fishes, in
the edge of the creature's snout, where a line running along the
back would bisect a line running along the belly; but this part
is less perfectly shown by my specimens than any other. The two
arms, or paddles, are placed so far forward as to give the body a
disproportionate and decapitated appearance. From the shoulder to
the elbow, if I may employ the terms, there is a swelling, muscular
appearance, as in the human arm; the part below is flattened, so
as to resemble the blade of an oar, and terminates in a strong,
sharp point. The tail--the one leg on which, as exhibited in one
of my specimens, the creature seems to stand--is of considerable
length, more than equal to a third of the entire figure, and of an
angular form, the base representing the part attached to the body,
and the apex its termination. It was covered with small tubercled,
rhomboidal plates, like scales, (see Plate I., fig. 3;) and where the
internal structure is shown, there are appearances of a vertebral
column, with rib-like processes standing out at a sharp angle. The
ichthyolite, in my larger specimens, does not much exceed seven
inches in length; and I despatched one to Agassiz, rather more than
two years ago, whose extreme length did not exceed an inch. Such
is a brief, and, I am afraid, imperfect sketch of a creature whose
very type seems no longer to exist. But for the purposes of the
geologist, the descriptions of the graver far exceed those of the
pen, and the accompanying prints will serve to supply all that may
be found wanting in the text. Fig. 1, in Plate I., and fig. 2, in
Plate II., are both restorations--the first of the upper, and the
second of the under, part of the creature. It may, however, encourage
the confidence of the naturalist, who for the first time looks upon
forms so strange, to be informed that Plate I., with its two figures,
was submitted to Agassiz during his recent brief stay in Edinburgh,
and that he as readily recognized in it the species of the two kinds
which it exhibits, as he had previously recognized the species of the
originals in the limestone.
[Illustration: _PLATE II._]
Agassiz, in the course of his late visit to Scotland, found six
species of the _Pterichthys_[J]--three of these, and the wings of a
fourth, in the collection of the writer. The differences by which
they are distinguished may be marked by even an unpractised eye,
especially in the form of the bodies and wings. Some are of a fuller,
some of a more elongated, form; in some the body resembles a heraldic
shield, of nearly the ordinary shape and proportions; in others the
shield stretches into a form not very unlike that of a Norway skiff,
from the midships forward. In some of the varieties, too, the wings
are long and comparatively slender; in others shorter, and of greater
breadth: in some there is an inflection resembling the bend of an
elbow; in others there is a continuous swelling from the termination
to the shoulder, where a sudden narrowing takes place immediately
over the articulation. I had inferred somewhat too hurriedly, though
perhaps naturally enough, that these wings, or arms, with their
strong sharp points and oar-like blades, had been at once paddles and
spears--instruments of motion and weapons of defence; and hence the
mistake of connecting the creature with the Chelonia. I am informed
by Agassiz, however, that they were weapons of defence only, which,
like the occipital spines of the river bull-head, were erected in
moments of danger or alarm, and at other times lay close by the
creature's side; and that the sole instrument of motion was the tail,
which, when covered by its coat of scales, was proportionally of a
somewhat larger size than the tail shown in the print, which, as in
the specimens from whence it was taken, exhibits but the obscure
and uncertain lineaments of the skeleton. The river bull-head, when
attacked by an enemy, or immediately as it feels the hook in its
jaws, erects its two spines at nearly right angles with the plates
of the head, as if to render itself as difficult of being swallowed
as possible. The attitude is one of danger and alarm; and it is a
curious fact, to which I shall afterwards have occasion to advert,
that in this attitude nine tenths of the _Pterichthys_ of the Lower
Old Red Sandstone are to be found. We read in the stone a singularly
preserved story of the strong instinctive love of life, and of the
mingled fear and anger implanted for its preservation--"The champions
in distorted postures threat." It presents us, too, with a wonderful
record of violent death falling at once, not on a few individuals,
but on whole tribes.
[Footnote J: Agassiz now reckons ten distinct species of
_Pterichthys_--_P. arenatus_, _P. cancriformis_, _P. cornutus_, _P.
major_, _P. Milleri_, P. latus, _P. oblongus_, _P. productus_, _P.
testudinarius_, and _P. hydrophilus_; of these, nine species belong
to the Lower, and one--the _Pterichthys hydrophilus_--to the Upper
Old Red Sandstone.]
[Illustration: _PLATE III._]
Next to the _Pterichthys_ of the Lower Old Red I shall place its
contemporary the _Coccosteus_ of Agassiz, a fish which, in some
respects, must have somewhat resembled it. Both were covered with
an armor of thickly tubercled bony plates, and both furnished
with a vertebrated tail. The plates of the one, when found lying
detached in the rock, can scarcely be distinguished from those of the
other: there are the same marks, as in the plates of the tortoise,
of accessions of growth at the edges--the same cancellated bony
structure within, the same kind of tubercles without. The forms of
the creatures themselves, however, were essentially different. I
have compared the figure of the _Pterichthys_, as shown in some of
my better specimens, to that of a man with the head cut off at the
shoulders, one of the legs also wanting, and the arms spread to the
full. The figure of the _Coccosteus_ I would compare to a boy's kite.
(See Plate III., fig. 1.) There is a rounded head, a triangular body,
a long tail attached to the apex of the triangle, and arms thin and
rounded where they attach to the body, and spreading out towards
their termination like the ancient one-sided shovel which we see
sculptured on old tombstones, or the rudder of an ancient galley.[K]
The manner in which the plates are arranged on the head is peculiarly
beautiful; but I am afraid I cannot adequately describe them. A ring
of plates, like the ring-stones of an arch, runs along what may
be called the hoop of the kite; the form of the keystone-plate is
perfect; the shapes of the others are elegantly varied, as if for
ornament; and what would be otherwise the opening of the arch, is
filled up with one large plate, of an outline singularly elegant. A
single plate, still larger than any of the others, covers the greater
part of the creature's triangular body, to the shape of which it
nearly conforms. It rises saddle-wise towards the centre: on the
ridge there is a longitudinal groove ending in a perforation, a
little over the apex, (Plate III., fig. 2;) two small lateral plates
on either side fill up the base of the angle; and the long tail, with
its numerous vertebral joints, terminates the figure.
[Footnote K: I have since ascertained that these seeming arms or
paddles were simply plates of a peculiar form.]
Does the reader possess a copy of Lyell's lately published elementary
work, edition 1838? If so, let him first turn up the description of
the Upper Silurian rocks, from Murchison, which occurs in page 459,
and mark the form of the trilobite _Asaphus caudatus_, a fossil of
the Wenlock formation. (See _Sil. Sys._, Plate VII.) The upper part,
or head, forms a crescent; the body rises out of the concave with a
sweep somewhat resembling that of a Gothic arch; the outline of the
whole approximates to that of an egg, the smaller end terminating
in a sharp point. Let him remark, further, that this creature was a
_crustaceous_ animal, of the crab or lobster class, and then turn up
the brief description of the Old Red Sandstone in the same volume,
page 454, and mark the form of the _Cephalaspis_, or buckler-head--a
_fish_ of a formation immediately over that in which the remains
of the trilobite most abound. He will find that the fish and the
crustacean are wonderfully alike. The fish is more elongated, but
both possess the crescent-shaped head, and both the angular and
apparently jointed body.[L] They illustrate admirably how two
distinct orders may meet. They exhibit the points, if I may so speak,
at which the plated fish is linked to the shelled crustacean. Now,
the _Coccosteus_ is a stage further on; it is more unequivocally a
fish. It is a _Cephalaspis_ with an articulated tail attached to the
angular body, and the horns of the crescent-shaped head cut off.
[Footnote L: Really jointed in the case of the trilobite; only
apparently so in that of the _Cephalaspis_. The body of the
trilobite, like that of the lobster, was barred by transverse,
oblong, overlapping plates, and between every two plates there was a
joint; the body of the _Cephalaspis_, in like manner, was barred by
transverse, oblong, overlapping scales, between which there existed
no such joints. It is interesting to observe how nature, in thus
bringing two such different classes as fishes and crustacea together,
gives to the higher animal a sort of pictorial resemblance to the
lower, in parts where the construction could not be identical without
interfering with the grand distinctions of the classes.]
Some of the specimens which exhibit this creature are exceedingly
curious. In one, a coprolite still rests in the abdomen; and a common
botanist's microscope shows it thickly speckled over with minute
scales, the indigestible exuviæ of fish on which the animal had
preyed. In the abdomen of another we find a few minute pebbles--just
as pebbles are occasionally found in the stomach of the cod--which
had been swallowed by the creature attached to its food. Is there
nothing wonderful in the fact, that men should be learning at this
time of day how the fishes of the Old Red Sandstone lived, and that
there were some of them rapacious enough not to be over nice in their
eating?
The under part of the creature is still very imperfectly known:
it had its central lozenge-shaped plate, like that on the under
side of the _Pterichthys_, but of greater elegance, (see Plate
III., fig. 3,) round which the other plates were ranged. "What an
appropriate ornament, if set in gold!" said Dr. Buckland, on seeing
a very beautiful specimen of this central lozenge in the interesting
collection of Professor Traill of Edinburgh,--"What an appropriate
ornament for a lady geologist!" There are two marked peculiarities
in the jaws of the _Coccosteus_, as shown in most of the specimens,
illustrative of the lower part of the creature, which I have yet
seen. The teeth, instead of being fixed in sockets, like those of
quadrupeds and reptiles, or merely placed on the bone, like those of
fish of the common varieties, seem to have been cut out of the solid,
like the teeth of a saw or the teeth in the mandibles of the beetle,
or in the nippers of the lobster, (Plate III., fig. 4;) and there
appears to have been something strangely anomalous in the position
of the jaws--something too anomalous, perhaps, to be regarded as
proven by the evidence of the specimens yet found, but which may
be mentioned with the view of directing attention to it. "Do not
be deterred," said Agassiz, in the course of one of the interviews
in which he obligingly indulged the writer of these chapters, who
had mentioned to him that one of his opinions, just confirmed by
the naturalist, had seemed so extraordinary that he had been almost
afraid to communicate it,--"Do not be deterred, if you have examined
minutely, by any dread of being deemed extravagant. The possibilities
of existence run so deeply into the extravagant, that there is
scarcely any conception too extraordinary for nature to realize." In
all the more complete specimens which I have yet seen, _the position
of the jaws is vertical, not horizontal_; and yet the creature, as
shown by the tail, belonged unquestionably to the vertebrata. Now,
though the mouths of the crustaceous animals, such as the crab and
lobster, open vertically, and a similar arrangement obtains among the
insect tribes, it has been remarked by naturalists, as an invariable
condition of that higher order of animals distinguished by vertebral
columns, that their mouths open horizontally. What I would remark as
very extraordinary in the _Coccosteus_--not, however, in the way of
directly asserting the fact, but merely by way of soliciting inquiry
regarding it--is, that it seems to unite to a vertebral column a
vertical mouth, thus forming a connecting link between two orders of
existences, by conjoining what is at once their most characteristic
and most dissimilar traits.[M]
[Footnote M: These statements regarding the character of the teeth
and the position of the jaws of the _Coccosteus_ have been challenged
by very high authorities. I retain them, however, in this edition
in their original form, as first made nearly six years ago. In at
least two of my specimens of Coccosteus the teeth and jaw form
unequivocally but one bone--a result, it is not improbable, of some
after anchylosing process, but which still solicits inquiry as not
yet definitely accounted for. The matter of fact in the case is
certainly one which should be determined, not analogically, but on
its own proper evidence, as furnished by good specimens. As for
the remark regarding the probable position of the creature's jaws,
it was ventured on at first, as the reader may perceive, with much
hesitation, and must now be regarded as more doubtful than ever.
Its repetition here, however, will, I trust, be regarded as simply
indicative of a wish on the part of the writer, that the question
be kept open just a little longer, and that further examination
be made. There is certainly something very peculiar about the
mouth of the Coccosteus not yet understood, and singularly formed
plates, connected with it, which have not been introduced into any
restoration, and the use of which in the economy of the animal
seem wholly unknown. [1850.--I have at length found a very perfect
specimen of the nether jaw of _Coccosteus_, and am prepared to show
that it was of a character altogether unique. It had its two groups
of from six to eight teeth, (exactly where, in the human subject, the
molars are placed,) that seem to have acted on corresponding groups
in the intermaxllaries, and two other groups of from three to five
teeth placed at right angles with these, direct in the symphysis,
and that seem to have acted on each other. But though these unique
teeth of the symphysis formed a vertical line of mouth, it joined
on at right angles to a transverse line of the ordinary type, as
the upright stroke of the letter T joins on to the horizontal line
a-top.] Fourth Edition.]
I am acquainted with four species of _Coccosteus_--_C. decipiens_,
_C. cuspidatas_, _C. oblongus_, and a variety not yet named; and
many more species may yet be discovered.[N] Of all the existences of
the formation, this curious fish seems to have been one of the most
abundant. In a few square yards of rock I have laid open portions of
the remains of a dozen different individuals belonging to two of the
four species, the _C. decipiens_ and _C. cuspidatus_, in the course
of a single evening. None of the other kinds have yet been found at
Cromarty. These two differed from each other in the proportions
which their general bulk bore to their length--slightly, too, in
the arrangement of their occipital plates. The _Coccosteus latus_,
as the name implies, must have been by much a massier fish than the
other; and we find the arch-like form of the plates which covered its
head more complete: the plate representing the keystone rests on the
saddle-shaped plate in the centre, and the plates representing the
spring-stones of the arch exhibit a broader base. The accompanying
print (Plate III.) represents the _Coccosteus cuspidatus_. The
average length of the creature, including the tail, as shown in most
of the Cromarty specimens, somewhat exceeded a foot. A few detached
plates from Orkney, in the collection of Dr. Traill, must have
belonged to an individual of fully twice that length.
[Footnote N: A fifth species has been named _C. maximus._]