begins it.

With the Permian formation, the palæo- Where zōic era terminates, and the Secondary begins. This period is sub-divided into four great How subgroups, the lowest of which is termed the Triassic,

What their character.

Last period called

what.

This peri

then comes the Oölit'ic, then the Wealden, and lastly the Cretaceous, which closes the system. All these groups are stratified, and originated in the wearing away of more ancient rocks.

The Palæo-zoïc period may be termed the age of fishes. Fishes were then the masters of the earth, and there were few reptiles and no land animals to dispute their dominion.

With equal propriety the Secondary period od what. may be called the age of reptiles, as these creatures then lorded it over water, land, and air, and were immensely numerous.

How subdivided.

They may be subdivided into three classes: sea-lizards, land-lizards, and winged-lizards. Only the first of these appear in the trias; the other two abound in the rest of the system.

The lowest

SECTION I.

FOSSILS OF THE TRIAS.

The Age of Footprints.

The lowest of the four Secondary rocks is groupwhat the triassic or saliferous group.

What does

the mean.

word

Triassic means triple or three-fold; a term applied to this group of rocks, because in Germany it contains three distinct portions of marl, limestone, and sandstone.

Why inap- In England the second portion does not propriate. exist, and the word trias is unsuitable; but, nevertheless, it is very generally adopted. Sometimes the group is called the saliferous, on account of its brine springs and rock-salt.

What next

After leaving the Permian formation, the takes place geological traveller enters into an entirely

new region. The scenery is different, the plants are different, the animals different, the very climate is different.

ence what.

Instead of black, blue, and grey limestone, The differ the soil is yellow, red, and white sand; and instead of dark shale we have red, green, and blue marls. Instead of a torrid heat, the temperature is only subtropical.

differ how,

The zoöphytes all differ in character from The fossils those of the preceding strata; the brach'iopods disappear, and are replaced by other bivalve shells of a higher order.

seas differ how.

The seas are less deep; and instead of being The tyrannized over by cephalopods* as before, are under the despotic sway of marine reptiles, called saurians or sea-lizards.

§ 1.-SEA-LIZARDS OF THE TRIAS.

saurians.

The marine saur'ians or sea-lizards of the Name the triassic period were ich'thyo-saurs, plēsiosaurs, rhyn'cho-saurs, and labyrinth'ŏdons.

What else

Besides these, turtles were very abundant, met with. though not like those which now exist; and the foot-prints of birds have been discovered.

The period

The triassic period is termed the age of foot-how called prints, from the number of fossilized impressions discovered in the strata; such as the foot-prints of frog-lizards, turtles, and of birds whose feet are adapted to running.

These are gallinaceous birds, of which peacocks, pheasants, turkeys, cocks and hens, partidges, grouse, and so on, are familiar examples. The feet of this class of birds are not webbed, and the soles of the toes are rough.

* Cephalopods, a class of molluscs, whose mouth unites beneath the body. They were the powerful instruments in the palæo-zoïc period for keeping down the superabundant tribes of marine creatures.

ICHTHYO-SAURUS.

From the Greek ixtis-σaûpos a fish-lizard.

Ichthyo

The word ich'thyo-saur* means a fish-lizard. saur what. About 12 distinct species have been found in the secondary formations.

What was its size.

What was it like.

Describe

;

It varied in size from 30 feet to about 50 was very fierce; preyed upon fish and reptiles; and lived in the deep seas, although sometimes it crawled upon the sandy beach to sleep or bask in the hot sun.

Its general appearance was that of a huge porpoise, with four paddles and a long tail. Its body was without scales, but covered with a thick skin.

It had the snout of a porpoise, the head and its form. chest of a lizard, the back-bone of a fish, the tail of a crocodile, and the paddles of a whale.

Describe

Its vast jaws would stretch seven feet wide. its jaws. Its teeth were like those of a crocodile, and it had as many as 110 in the upper jaw, and 100 in the lower.

Describe

Its enormous eyes were set in sockets 18 its eyes. inches in diameter; and were defended by bony plates like the eyes of a hawk, owl, or eagle.

Describe

Its fore-paddles were long, and contained its parts. 100 different bones; its hind ones were smaller, and had fewer bones.

What were

Its backbone admitted of the utmost freedom its physics. of motion. Its short thick neck shews that

* Ichthyo-saur, pronounce Ik'-theö-saur.

the muscular strength of the creature was very great. Its teeth prove it to have been carnivorous; and its paddles aquatic.

it move.

Its motion on land must have been slow and How could awkward, but in deep water it could cleave its way with surprising rapidity.

PLESIO-SAURUS.

From two Greek words manoíos-oaupos akin-to a lizard.

saur what.

The word plēsio-saur means akin to a lizard, The plesioand the creature so called certainly approximated to the lizard-type more than the fish. About 20 species have been discovered in the secondary formations.

its size.

The long-headed plesio-saur was 18 feet What was from snout to tail, of which eight were occupied by its neck; its tail was very short; and the girth of its body was about seven feet.

Its head was small and lizard-like; its neck Describe very long and like a serpent; its body was of

its form.