kind extended also over a wide area, reaching from
England to the Caucasus, and perhaps continuing as
far as southern India : a new series of animals came
into existence throughout the district, while a con-
stant succession of alterations of the level of the sea-
bottom sometimes produced slight elevations, but
more frequently, and on the whole, considerable de-
pression. In this way was marked the commence-
ment of the new period, and during the early part
of it the deposit of the bed called "lower green-



228 PICTURESQUE SKETCHES

sand." This bed is of moderate thickness in Eng-
land, but of far greater importance in this respect in
some parts of the Continent, where it is manifestly
the representative of an extensive and long- continued
series of operations. During this period the prevail-
ing material deposited was, in England, sand, varied
occasionally by calcareous and muddy bands, but on
the Continent it includes many beds of limestone.
The sands contain a good number of fossils very dis-
tinct from those of the oolitic period, so that the de-
posit of the Wealden beds had either occupied so long
a time that the species in the neighbouring seas had
died out and been succeeded by others, or else the
commencement of the deposition of these beds had
been marked by the introduction of a new series of
typical forms.

The deposit of lower greensand was probably
made in a sea which in the south of England was
either shallow, or at least not extremely deep ; and
the bed of clay called gault, which rests upon the
lower greensand, contains forms for the most part
quite distinct from it. The group of deposits called
on the Continent " Neocomiari* is nothing more than
the typical form of these older or lower sandy beds,
either immediately succeeding the Weald or resting
directly on the oolite, though not deposited on the
latter beds till after a long interval had elapsed,
during which, probably, the oolitic rocks had formed
dry land*

The gault, or blue clay reposing on the lower
greensand, is itself succeeded by another thin and
less important bed of sand, also containing pale green
particles, and for that reason called " upper green-



OF CREATION. 229

sand;" and this again gives place to the lower chalk.
The upper greensand is generally barren of fossils,
and was most likely formed rapidly in a shallow sea.
After it was deposited the sea-bottom probably sunk
more rapidly, previously to the great change indicated
in the chalk beds above.

The depression of the sea-bottom, which probably
went on, with few alternations of elevation, during
the greater part of the deposit of the chalk, was a
very important phenomenon, and altered, as may be
supposed, the general character of the marine fauna
in almost every important respect. We at once lose
the species usually predominant in shallow water and
on a coast-line, and either obtain deep sea or free-
swimming animals, or else find the deposit singularly
barren of all organic remains. But, as it is not to be
supposed that a continued depression, amounting in
the whole to many hundred fathoms, could take place
without considerable effect being produced on the
beds beneath the surface, and since such depression
was perhaps accompanied by a partial upheaval in
some other subterranean tract, it will not be thought
extraordinary if the effects of submarine volcanic
action are also met with connected with this period.
Among such effects may have been the outpouring of
large quantities of silica, either in solution in hot
water, or thrown out in the state of vapour ; and in
this way we may possibly account for the layers of
flint alternating with the pure white carbonate of
lime of which the chalk mainly consists.

In the early part of the cretaceous period the ani-
mal kingdom was represented by species which ex-
hibit striking differences when compared with those of



230 PICTURESQUE SKETCHES

the oolites, so far as the Invertebrata are concerned,
while the same large marine saurians seem to have
been continued. This may readily be understood, if
we suppose, that, in the interval between the deposit
of the uppermost marine oolites and the lower green-
sand there was an extensive tract of land at some
distance from the districts examined. I know of no
other hypothesis by which the facts can be explained ;
and this view is extremely probable in itself, and
answers the conditions of the problem. To this view
I shall have occasion again to recur.

When, however, towards the close of the deposits
of greensand, the sea began to deepen, the character
of the fauna also changed, and we find gradually
fewer indications of the neighbourhood of land, either
by fragments of land fossils, or by any indications of
those molluscous animals which prefer for their habita-
tion the shallow water near a coast-line. The animals
and other remains of greatest interest that we shall
have to consider as characterising the chalk are thus
either free-swimming, or their nearest analogues are
known to inhabit deep water. They include sponges,
the minute animals called Foraminifera., those still
more minute microscopical animalcules called Infu-
soria, various forms of encrinites and other Eadiata,
cephalopodous and other mollusks, a few fishes, and
some, but still fewer, reptiles. Most of the species
are peculiar to the formation, but there is a manifest
approximation to the existing forms of animals, not
only in those of low organization, but also in the
fishes.

In the most ancient seas we find abundant exam-
ples of the work, of those singular beings, which, in



OF CREATION. 231

spite of the continual encroachment of the waves, and
in defiance of storms and external violence, have
always been endowed with a rapidity of increase
greater beyond comparison than that of the more
highly organized animals. These little creatures have,
in the lapse of ages, been enabled to build up the
most solid and enduring monuments, and have con-
structed mountains of coral limestone, which charac-
terise each separate formation ; and some of their
race continued throughout the secondary period in
the part of the world we now inhabit. They were
represented abundantly during the deposit of the
chalk; and a vast multitude of sponges, organic
bodies even less advanced in the scale of organiza-
tion, were spread over the sea-bottom, and appear
to have been destroyed from time to time by sudden
irruptions of chalky mud.

The horny net-work commonly known as the
sponge is nothing more than the frame- work of a very
peculiar kind of vegetable. The whole surface of a
living sponge is covered with minute apertures, with
large ones distributed at intervals, and the water is in
some way made to enter the small pores in a con-
tinual current, which passes out again by those of
larger size. It cannot be doubted that these currents
are connected with the supply of nutrition ; but in
what way the current is produced, or what are the
actual conditions of existence, naturalists have not
yet been able to discover.

The sponge as commonly known is made up of
horny fibres, but a large number of varieties exist, in
which spiculae, or little needle-shaped crystallized par-
ticles of flint or carbonate of lime, separated from the



232 PICTURESQUE SKETCHES

surrounding water, replace these horny fibres, so that
the frame- work becomes more or less entirely made
up of them, and assumes a different character. A body
in this state when exposed to the influence of water
in which siliceous or flinty matter is abundantly pre-
sent, would, as we know by observation in similar
cases, attract to itself the particles of siliceous matter
in the water, and become fossilised and surrounded
with silica. Such has been, perhaps, the history of
those singular layers of flint which characterise the
upper beds of chalk ; and it is quite certain that care-
ful examination under the microscope often shows
very distinctly in such flints a fine net-work of fibres
like those which we know to exist in sponges. The
annexed figure (82) will give an idea of the appear-
ance of such fibres in flint when greatly magnified.

Fig. 82




FOSSIL SPONGE



The forms of the sponges themselve are not unfre-
quently preserved in that of the flint into which



OF CREATION.



233



Fig. 83



they are now changed, and in this way we occasion-
ally find grotesque shapes resembling in form various
familiar objects.

In the sand associated with the chalk, the very
spongeous bodies themselves, exhibiting on their sur-
face the peculiar marks and apertures characteristic of
them, are also met with in a perfect state. The
figure marked (83) represents a common form.

Flints, when examined
with the aid of a good micro-
scope, not only exhibit a net-
work of fibres, but also show
entangled amongst the fibres
a vast multitude of exceed-
ingly minute bodies, the re-
mains of a group of animals
known to naturalists as "in-
fusorial animalcules," and of
late years investigated with
great care by M. Ehrenberg.

The skeletons of these
little creatures exist not
only in the recesses of the
chalk flints, but they also abound in many parts of
the solid matter of the chalk itself, so that a large
part of this rock would seem to be made up of the
fragmentary skeletons of these most minute animals,
whose very existence would be unknown to us with-
out the assistance of powerful microscopes.

To give such an idea as can be conveyed by num-
bers, it will be sufficient to say, that, with regard to
some species, as many as twenty-two thousand indivi-
duals might be placed in a row on a linear inch of




POLYPOTHECIA.



234



PICTURESQUE SKETCHES



surface, while they are often crowded together so
closely in putrid water, that one cubic inch of water
in that state contains more of these animalcules than
there are human beings on the globe. They increase,
too, so rapidly, that, according to a calculation care-
fully made, as many as 800,000,000 may be derived
from a single individual in the course of a month
in summer. The method of effecting locomotion and
obtaining food is not less singular and interesting in
these animals than their minute proportions, and is
derived from the possession of very numerous fine hair-




INFUSORIAL ANIMALCULES.*

like appendages called cilia, by the constant vibration
of which a current is produced in the water.

The shapes of the hard part or skeleton of the
animalcules found in the chalk, in flints, and else-
where, are many of them extremely curious and
beautiful. Some specimens appear to consist of tubes



* Fig. 84, Gomphonema. Fig. 85, Bacillaria.
Fig. 87, Xanthidium. Fig. 88, Gaillionella.



Fig. 86, Navicula.



OF CREATION. 235

placed edgeways, and projecting one beyond another;
others are also tubes, but placed parallel one with an-
other on long lines of fragile riband transversely to the
direction of the riband (fig. 85). Others, again, are
oblong figures united at the edges ; while one group,
more complicated than the rest, exhibits numerous
projections of the most singular shapes (Xanthidium,
fig. 87).

It cannot but be a matter of great interest to learn,
if possible, the use of these minute animals in the
economy of nature. That they are not merely acci-
dents in creation we may be quite certain, and that
they simply enjoy life, and do not contribute to the
well-being of the whole, may be considered equally
improbable, and too unlike the ordinary course of
nature, to be admitted for a moment. All things
work together, and we may, in all cases, safely
inquire concerning the adaptation of any group, how-
ever minute or apparently unimportant it may at
first appear.

It has been ingeniously suggested by Professor
Owen that these little creatures are the appointed
devourers of organic matter immediately before its
final decomposition into inorganic elements. " For
consider," says he, " their incredible numbers, their
universal distribution, their insatiable voracity, and
their invariable presence wherever animal or vege-
table matter is undergoing decomposition in water.
Surely we must be indebted to them the ever ac-
tive and invisible scavengers of the world for the
salubrity of our atmosphere ; but they perform a
still more important office, perhaps, in preventing
the gradual diminution of the present amount of
organized matter upon the earth.



236 PICTURESQUE SKETCHES

" And it is not difficult to understand in what way
this result is produced, for, when the organic matter
is in that state of comminution and decay which im-
mediately precedes its return from the organic to the
inorganic world, these wakeful members of nature's
invisible police are everywhere ready to arrest the
fugitive particles, and turn them back into the ascend-
ing stream of animal life. Becoming the food of the
smaller infusorial animalcules, they again supply the
voracity of the larger ones, and of numerous other
small animals, which in their turn are devoured by
larger ones, and so, by degrees, the substance fit for
the nourishment of the most highly organized classes
is brought back by a short route from the extremity
of the realms of organized matter."

It is a remarkable and very interesting fact with
regard to these animalcules, that their light, though
siliceous skeletons, are capable of being transported
by the air in the form of fine dust to the distance of
many hundred miles out at sea ; and the quantity so
transported is often sufficient to cloud the air, and
form a sensible deposit on the decks and rigging of
ships. The microscope alone is capable of proving
whence this dust comes, but, with its aid, they can
be recognized, identified, and traced to that conti-
nent or island, which is not always the one nearest
at hand, where they are indigenous. It will not
be surprising, also, since we thus find the bodies
of the animalcules themselves carried along by mil-
lions through the air, that their eggs may be carried
yet farther, and prove a bond of union between dis-
tant lands, whose other inhabitants have no relation.
Who could have imagined that the atmosphere is in



OF CREATION.



237



this way the means of conveying to distant spots
the invisible stony frame- work and the eggs of these
little bodies ? and yet it is impossible to doubt the
importance of such a means of communication in the
animal economy.

But the animalcules, singular and interesting as
they are, form but one of several groups of ani-
mals of low organization that inhabited the sea
during the deposit of the chalk. The sea bottom
abounded with sponges of all kinds, as we have
already seen; and floating about near the surface,
there must also have existed a vast number of mi-
nute animals enclosed in shells formed of a number
of chambers or compartments, belonging to a group
now common in many seas and known by the name
Foraminifera.



89 90 91 92 93




FORAMINIFERA.*

The animals thus named occupy all the various
chambers of their habitation, and not merely, as in
the nautilus, the outermost one. They appear to
possess a more perfect organization than the polyps,
but are less complicated than the encrinites. Their
body is simple and gelatinous, no distinct organs being
recognisable in it. In size they vary from dimen-

* Fig. 89, Guttulina. Fig. 90, Rosalina. Fig. 91, Siderolina.
Fig. 92, Cristellaria. Fig. 93, Nodosaria.



238



PICTURESQUE SKETCHES



sions perfectly microscopic, and absolutely invisible to
the naked eye, to about the bigness of a five-shilling
piece. In shape their habitation is sometimes flat
and disc-like, resembling a piece of money, and some-
times it presents the most singular modifications of
form, including every variety that can be conceived
to arise from the indiscriminate heaping together of a
great number of very differently shaped chambers, as
unlike one another in size as they are in shape.

Animals of this low organization multiply rapidly,
and are capable of making very important geological
deposits. While, indeed, the vertebrated animals
and the larger and more complicated mollusks live
for some considerable time, and modify during that
time the general conditions of organic existence, these
little creatures the coral animal, the animalcule, and
the Foraminifera may, by their rapid secretion of
solid matter from the water, and (owing to their
brief existence) equally rapid deposition of it in a
solid form, lay the foundation of islands, and even of
new continents. The land thus formed may, when
brought above the sea level, be destined to last, with
little change, throughout many successive geological
epochs, during which group after group of species of
the higher animals may be introduced and destroyed,
some of which leave no indication of their ever having
existed, while others are represented by a few bones,
a tooth, a scale, or perhaps only by the faint impress
of a footstep.

How important, then, it becomes that we should
understand these, the common hieroglyphics, even if
their meaning is less full, and when they talk an ear-
lier and a simpler language than the others, since the
sacred characters which speak of higher events are so



OF CREATION



239



infinitely more rare, and for that reason also more dif-
ficult to render. The most enduring monuments of
man himself his cities, his pyramids, and his lofty
columns are, in many cases, built of these far more
ancient and far more lasting objects, which withstand
the shock of earthquakes and the hand of time, and
which scarcely yield, even at last, to the slow in-
fluence of crystalline forces, re-arranging the particles
by the aid of heat and electricity.



Fig. 94



Many species of
radiated animals
animals developed
more or less in a
star- shape, and form-
ed of five parts or
rays are common
in the chalk (see fig.
94) ; but the elegant
lily encrinites of the
older periods had
now dwindled to a
few species of small
size and diminish-
ed beauty. One of the less common, but most pe-
culiar forms of these creatures, has the form of a
pouch, or rather, perhaps, of an egg open at the top.
The whole is built up of plates accurately fitting one
another; and arms proceeded from the summit, sur-
rounding the mouth. The shell or case, which
was not supported on a stem, is known to naturalists
by the name of Marsupite ;* and one cannot easily




STAR FISH.



* Marsupium, a pouch or purse, from the resemblance of the shell
to a pouch.



240



PICTURESQUE SKETCHES



Fig. 95



imagine how an animal provided with so
heavy a covering could move about. It
may have been permanently attached,
though no stem appears, and possibly it
was provided with a membrane project-
ing between the plates, and coating their
external surface.

The true encrinites are not very com-
mon in the chalk, and this is especially
the case in our own country. Some re-
markable forms occur on the Continent,
and one of these is represented in the
annexed figure (95), but they are rarely
in a perfect state.

Besides these radiated animals, many
others of various kinds, and perfectly en-
closed in a stony case, such as sea-urchins,
&c., are found in the chalk, especially
in particular localities, and are accom-
panied by the remains of crabs and lob-
sters, some of them belonging to that tribe
of hermit crabs (fig. 96) which have no cal-
careous cover-
ing except up-
on the claws,
and are oblig-
ed to make use
of the shells

of whelks and
PAGURUS. other un i va l ve

mollusca as habitations. It is interesting
to be able to trace the similarity of orga-

BOURGUETI- . , .

CRINUS. nization which enables us to recognise a




Fig. 96




OF CREATION.



241



character and habit of this kind, for it gives a
reality to the investigations of the palaeontologist,
and a familiarity and homeliness to his descriptions,
which cannot fail to be pleasing and satisfactory.

Bivalve as well as univalve shells are found abun-
dantly, but not universally, in the chalk ; and some
districts in the south of France seem to be remark-
able for the singular and extreme development of one
group, of which, so far as can be told, there are no
living representatives. Their shells were perma-
nently fixed to some solid body. The structure
of the shell is peculiar and of great thickness and
strength, from which we may safely conclude that
the animal had no need of motion when once es-
tablished in its house. One such genus is called



Fig. 97



Sphcerulite, another
is the Hippurite ;
but there are seve-
ral belonging to this
group, and they seem
most nearly allied
to the inhabitants
of those univalve
shells of which the
limpet is the pre-
sent representative.
I have figured a spe-
cies of Sphserulite,
to give an idea of
the ancient form of the shell of this group.

Three common and characteristic forms of creta-
ceous bivalve shells are also figured. One of them,
called Inoceramus (fig. 100), is a shell whose remains




SPHJERULITE.



242 PICTURESQUE SKETCHES

are frequently found in the chalk, but which has
no living representative. It often attained a large

Fig. 98 Fig. 99





TRIGONIA. PLICATULA.

size, and its hinges being singularly thick and pon-
derous, while the shell was often thin, it is not un-
common to find fragments of the more solid portion
detached. The Trigonia (fig. 98) is the ancient
representative of a genus still found, and not uncom-

Fig. 100





TEREBRATULA.



INOCERAMUS.

mon on the coast of Australia, but now absent from
the northern hemisphere ; and the other, Plicatula
(fig. 99), is one of a larger group, nearly allied to
the oyster, and very common throughout the creta-




OF CREATION. 243

ceous period. The Terebratulae (fig. 101) were also
abundant during the whole period, and continued
quite to its close.

The univalve shells of this period are also interest-
ing. Of those nearly allied to existing forms, the
annexed figure (102) is a good example. Fig. 102
But the most remarkable, beyond all com-
parison, are the indications of the ancient
Cephalopoda at this the last point of their
development. These animals, having been
developed throughout the lias and oolitic
period in extreme abundance, were conti-
nued in the cretaceous rocks, and there TORNATELLA.
seem to have expanded into a vast multitude of
strange forms before becoming finally extinct.

The forms thus assumed were curious, and the
exact bearing of them upon the habits of the animal
it is by no means easy to recognise. The most sim-
ple form in which an animal forms a habitation con-
sisting of a number of compartments may be under-
stood by examining any univalve shell. The greater
part of the animal is inclosed in a muscular sac called a
mantle, capable of depositing carbonate of lime. As
soon as one coat is deposited, which, of course, as-
sumes the shape of the muscular mantle, the simple
shell is perfected. If, as the animal grows, it is
developed in a spiral form, the shell increases at the
aperture ; but if the extremity does not adapt itself
to the original shell, and remain always of the same
size, it must, as it increases in size, withdraw itself
from its former compartment, and build a wall of par-
tition, and in this way we have the first step towards
the formation of the shell of the ammonite or nau-

M 2



244



PICTURESQUE SKETCHES



tilus, the generic distinction being founded partly on
the position of a siphon or tube which connects one
chamber with another, partly on the shape of the
mantle.

It is easy to imagine, however, that in thus de-
i. 103 veloping itself round

an axis, the successive
whorls may or may not
actually touch one an-
other. The common
Spirula is an example
of the latter structure
in a recent shell ; and
the shell called Crio-
ceratite* (103) corre-
sponds with the ammo-
nite, much as the spirula corresponds with the nautilus.
Again, if, instead of being thus formed continu-
ously in a spiral, the animal at particular periods of
its growth went off in a straight form, and then again
curved, we should have a hooked shell resembling
that figured in the annexed cut, and called a Ha-

Fig. 104




CRIOCERATITE.




HAMITE.

mite\ (104), or another having a more boat-like form,
and called by naturalists Scaphite.^ But if, instead of



* Kpiof (cn'os), a battering-ram ;
f 'A/LIJJ (/me), a reaping-hook.



ceras\ a horn.
% SiccHpoQ (scaphos), a boat.



OF CREATION.



245



r~.
31



curving, it went on straight from the first, we should
then have a straight shell, in all important respects