The terrestrial flora of this age was composed of Ferns, Cycads, and
Conifers. The first represented by the _Pachypteris microphylla_, the
second by _Zamites Moreana_. _Brachyphyllum Moreanum_ and _B. majus_
appear to have been the Conifers most characteristic of the period;
fruits have also been found in the rocks of the period, which appear to
belong to Palms, but this point is still obscure and doubtful.
Numerous vestiges of the fauna which animated the period are also
revealed in the rocks of this age. Certain hemipterous insects appear on
the earth for the first time, and the Bees among the Hymenoptera,
Butterflies among the Lepidoptera, and Dragon-flies among the
Neuroptera. In the bosom of the ocean, or upon its banks, roamed the
_Ichthyosaurus_, _Ceteosaurus_, _Pterodactylus crassirostris_, and the
_Geosaurus_; the latter being very imperfectly known.
The Ceteosaurus whose bones have been discovered in the upper beds of
the Great Oolite at Enslow Rocks, at the Kirtlington Railway Station,
north of Oxford, and some other places, was a species of Crocodile
nearly resembling the modern Gavial or Crocodile of the Ganges. This
huge whale-like reptile has been described by Professor John Phillips as
unmatched in size and strength by any of the largest inhabitants of the
Mesozoic land or sea--perhaps the largest animal that ever walked upon
the earth. A full-grown Ceteosaurus must have been _at least_ fifty feet
long, ten feet high, and of a proportionate bulk. In its habits it was,
probably, a marsh-loving or river-side animal, dwelling amidst filicene,
cycadaceous, and coniferous shrubs and trees full of insects and small
mammalia. The one small and imperfect tooth which has been found
resembles that of Iguanodon more than of any other reptile; and it seems
probable that the Ceteosaurus was nourished by vegetable food, which
abounded in the vicinity of its haunts, and was not obliged to contend
with the Megalosaurus for a scanty supply of more stimulating diet.[69]
[69] For a full account of the Ceteosaurus, see “The Geology of the
Thames Valley,” by Prof. John Phillips, F.R.S. 1871.
Another reptile allied to the Pterodactyle lived in this epoch--the
_Ramphorynchus_, distinguished from the Pterodactyle by a long tail. The
imprints which this curious animal has left upon the sandstone of the
period are impressions of its feet and the linear furrow made by its
tail. Like the Pterodactyle, the Ramphorynchus, which was about the size
of a crow, could not precisely fly, but, aided by the wing (a sort of
natural parachute formed by the membrane connecting the fingers with the
body), it could throw itself from a height upon its prey. Fig. 119
represents a restoration of this animal. The footprints in the soil are
in imitation of those which accompany the remains of the Ramphorynchus
in the Oolitic rocks, and they show the imprints of the anterior and
posterior feet and also the marks made by the tail.
This tail was very long, far surpassing in length the rest of the
vertebral column, and consisting of more than thirty vertebræ--which
were at first short, but rapidly elongate, retain their length for a
considerable distance, and then gradually diminish in size.
[Illustration: XVIII.--Ideal landscape of the Middle Oolitic Period.]
Another genus of Reptiles appears in the Middle Oolite, of which we have
had a glimpse in the Lias and Great Oolite of the preceding section.
This is the _Teleosaurus_, which the recent investigations of M. E.
Deslongchamps allow of re-construction. The Teleosaurus enables us to
form a pretty exact idea of these Crocodiles of the ancient seas--these
cuirassed Reptiles, which the German geologist Cotta describes as “the
great barons of the kingdom of Neptune, armed to the teeth, and clothed
in an impenetrable panoply; the true filibusters of the primitive seas.”
[Illustration: Fig. 119.--Ramphorynchus restored. One-quarter natural
size.]
The Teleosaurus resembled the Gavials of India. The former inhabited the
banks of rivers, perhaps the sea itself; they were longer, more slender,
and more active than the living species; they were about thirty feet in
length, of which the head may be from three to four feet, with their
enormous jaws sometimes with an opening of six feet, through which they
could engulf, in the depths of their enormous throat, animals of
considerable size.
The _Teleosaurus cadomensis_ is represented on the opposite page (PLATE
XVIII.), after the sketch of M. E. Deslongchamps, carrying from the sea
in its mouth a _Geoteuthis_, a species of Calamary of the Oolitic epoch.
This creature was coated with a cuirass both on the back and belly. In
order to show this peculiarity, a living individual is represented on
the shore, and a dead one is floating on its back in shallow water,
leaving the ventral cuirass exposed.
Behind the _Teleosaurus cadomensis_ in the engraving, another Saurian,
the _Hylæosaurus_, is represented, which makes its appearance in the
Cretaceous epoch. We have here adopted the restoration which has been so
ably executed by Mr. Waterhouse Hawkins, at the Crystal Palace,
Sydenham.
Besides the numerous Fishes with which the Oolitic seas swarmed, they
contained some Crustaceans, Cirripedes, and various genera of Mollusca
and Zoophytes. _Eryon arctiformis_, represented in Fig. 119, belongs to
the class of Crustaceans, of which the spiny lobster is the type. Among
the Mollusca were some Ammonites, Belemnites, and Oysters, of which many
hundred species have been described. Of these we may mention _Ammonites
refractus, A. Jason and A. cordatus, Ostrea dilatata, Terebratula
diphya, Diceras arietena, Belemnites hastatus_, and _B. Puzosianus_. In
some of the finely-laminated clays the Ammonites are very perfect, but
somewhat compressed, with the outer lip or margin of the aperture entire
(Fig. 120). Similar prolongations have been noticed in Belemnites found
by Dr. Mantell in the Oxford Clay, near Chippenham.
[Illustration: Fig. 120.--Eryon arctiformis.]
[Illustration: Fig. 121.--Perfect Ammonite.]
Among the Echinoderms, _Cidaris glandiferus_, _Apiocrinus Roissyanus_,
and _A. rotundus_, the graceful _Saccocoma pectinata_, _Millericrinus
nodotianus_, _Comatula costata_, and _Hemicidaris crenularis_ may be
mentioned; _Apiocrinites rotundus_, figured in PLATE XIX., is a reduced
restoration: 1, being expanded; _a_, closed; 3, a cross section of
the upper extremity of the pear-shaped head; 4, a vertical section
showing the enlargement of the alimentary canal, with the hollow
lenticular spaces which descend through the axis of the column, forming
the joints, and giving elasticity and flexure to the whole stem, without
risk of dislocation. _A. rotundus_ is found at Bradford in Wiltshire,
Abbotsbury in Dorset, at Soissons, and Rochelle. This species--known as
the Bradford Pear-Encrinite--is only found in the strata mentioned.
[Illustration: XIX.--Fig. 1.--Apiocrinites rotundus. Fig. 2.--Encrinus
liliiformis.]
The Corals of this epoch occur in great abundance. We have already
remarked that these aggregations of Polyps are often met with at a great
depth in the strata. These small calcareous structures have been formed
in the ancient seas, and the same phenomenon is extending the
terrestrial surface in our days in the seas of Oceania, where reefs and
atolls of coral are rising by slow and imperceptible steps, but with no
less certainty. Although their mode of production must always remain to
some extent a mystery, the investigations of M. Lamaroux, Mr. Charles
Darwin, and M. D’Orbigny have gone a long way towards explaining their
operations; for the Zoophyte in action is an aggregation of these minute
Polyps. Describing what he believes to be a sea-pen, a Zoophyte allied
to _Virgularia Patagonia_, Mr. Darwin says: “It consists of a thin,
straight, fleshy stem, with alternate rows of polypi on each side, and
surrounding an elastic stony axis. The stem at one extremity is
truncate, but at the other is terminated by a vermiform fleshy
appendage. The stony axis which gives strength to the stem, may be
traced at this extremity into a mere vessel filled with granular matter.
At low water hundreds of these zoophytes might be seen, projecting like
stubble, with the truncate end upwards, a few inches above the surface
of the muddy sand. When touched or pulled, they drew themselves in
suddenly, with force, so as nearly or quite to disappear. By this
action, the highly-elastic axis must be bent at the lower extremity,
where it is naturally slightly curved; and I imagine it is by this
elasticity alone that the zoophyte is enabled to rise again through the
mud. Each polypus, though closely united to its brethren, has a distinct
mouth, body, and tentacula. Of these polypi, in a large specimen there
must be many thousands. Yet we see that they act by one movement; that
they have one central axis, connected with a system of obscure
circulation.” Such is the brief account given by a very acute observer
of these singular beings. They secrete the calcareous matter held in
solution in the oceanic waters, and produce the wonderful structures we
have now under consideration; and these calcareous banks have been in
course of formation during many geological ages. They just reach the
level of the waters, for the polyps perish as soon as they are so far
above the surface that neither the waves nor the flow of the tides can
reach them. In the Oolitic rocks these banks are frequently found from
twelve to fifteen feet thick, and many leagues in length, and
preserving, for the most part, the relative positions which they
occupied in the sea while in course of formation.
The rocks which now represent the Middle Oolitic Period are usually
divided into the _Oxford Clay_, the lower member of which is an
arenaceous limestone, known as the _Kellaways Rock_, which in Wiltshire
and other parts of the south-west of England attains a thickness of
eight or ten feet, with the impressions of numerous Ammonites, and other
shells. In Yorkshire, around Scarborough, it reaches the thickness of
thirty feet; and forms well-developed beds of bluish-black marl in the
department of Calvados, in France. It is the base of this clay which
forms the soil (_Argile de Dives_) of the valley of the Auge, renowned
for its rich pasturages and magnificent cattle. The same beds form the
base of the oddly-shaped but fine rocks of La Manche, which are
popularly known as the _Vaches Noires_ (or black cows)--a locality
celebrated, also, for its fine Ammonites transformed into pyrites.
The _Oxford Clay_ constitutes the base of the hills in the neighbourhood
of Oxford, forming a bed of clay sometimes more than 600 feet thick. It
is found well-developed in France, at Trouville, in the department of
the Calvados; and at Neuvisy, in the department of the Ardennes, where
it attains a thickness of about 300 feet. It is a bluish, sometimes
whitish limestone (often argillaceous), and bluish marl. The _Gryphæa
dilatata_ is the most common fossil in the Oxford Clay. The _Coral Rag_
is so called from the fact that the limestone of which it is chiefly
composed consists, in part, of an aggregation of considerable masses of
petrified Corals; not unlike those now existing in the Pacific Ocean,
supposing them to be covered up for ages and fossilised. This coral
stratum extends through the hills of Berkshire and North Wilts, and it
occurs again near Scarborough. In the counties of Dorset, Bedford,
Buckingham, and Cambridge, and some other parts of England, the
limestone of the Coral Rag disappears and is replaced by clay--in which
case the Oxford Clay is overlaid directly by the Kimeridge Clay. In
France it is found in the departments of the Meuse, of the Yonne, of the
Ain, of the Charente Inférieure. In the Alps the _Diceras limestone_ is
regarded, by most geologists, as coeval with the English Coral Rag.