series lie towards the west; that of the Lower Greensand is seen in the Farringdon Gravels; that of the Gault in the Halden Sands. The Chalk proper filled up the deeper and subsiding sea-bed at a period synchronous with the deposition of some of these littoral beds, and at the time of the greatest extension of the area of the Cretaceous Ocean, the littoral beds of which are recognisable in the South of Norway and Sweden, in Westphalia and Rhenish Prussia, &c., and the area of which probably may be regarded as reaching from the Rocky Mountains at the head of the Missouri, over Texas, Florida, the eastern side of the Alleghanies, the West Indies, and a broad belt of the Atlantic, to North Africa, Central and Northern Europe, with bold extensions into Western, Central, and even Eastern Asia. Central Europe then presented the aspect of a huge archipelago from its many extensive islands, of which one of the largest was an area comprising the chief part of France, the north-east of Britain, Ireland, Norway, Sweden, Lapland, and what are now the separating channels; together with a part of the Atlantic to the west and south. From the northern part of the old land-area the author believes that the granitic boulder of Croydon was derived. And, as it is, in his opinion, too massive to have been transported by floating trees, as Mr. C. Darwin describes an isolated rock-fragment to have been conveyed to the coral-islands of the Keeling group, or by sea-weeds (the floating-powers of

which the author has studied in the English Channel),—Mr. GodwinAusten refers to an ice-floe as the agent by which such a block could alone have been lifted from the coast and conveyed far out to sea. The possible occurrence of rare and isolated boulders in the chalk-sea under such conditions was analogous, in Mr. Austen's opinion, to the occasionally extended voyage of icebergs at the present day to the coast of Ireland, the Azores, and even to the Madeira Islands.

[The large portion and several pieces of the granitic boulder and fragments of felspathic greenstone, from Croydon, presented by Dr. F. Young, are in the Geological Society's Museum; and several series of Pebbles, &c. from the Chalk, are in the Collections of the Rev. T. Wiltshire, F.G.S., W. Cunnington, Esq., F.G.S., W. Harris, Esq., F.G.S., J. S. Bowerbank, Esq., F.R.S., and H. Catt, Esq., and in the Society's Museum.]

GLOSSARY.

Explanations of most of the scientific terms not included in this Glossary are given in the text, and may be found by consulting the Index.

headless; molluscous animals without a head, as the Oyster, &c.

needle-like, sharp-pointed.

air-stones; mineral masses that fall from the atmosphere.

a family of marine plants.

water-borne materials, especially river-deposits of

recent formation.

clayey.

metallic base of clay.

sockets of the teeth.

shapeless; devoid of regular form.

almond-like; cellular volcanic rocks, the cavities

of which are filled with other substances.

branching and interlacing.

joints of bones immoveably united.

animals having an external integument formed of rings; as the Worm.

the feelers of insects.

flower-animals, as the Actinia.
stone-coal, or culm.

an extinct animal, allied to the palæotheria, found
in brown-coal.

destitute of wings; applied to a particular genus of bird.

tree-like.

sandy, or composed of sand.

clayey, or composed of clay.

animals without an internal skeleton, and having

jointed coverings, as Insects.

plants of the reed-tribe.

shell-less mollusks, shaped like a bottle.

a genus of corals.

a dark-green mineral found in many volcanic rocks pipe-scale fish.

heavy-spar; a mineral so called.

a lava, composed of augite and felspar; often columnar.

a series of deposits formed in a depression of older rocks, or bent up into a basin-like or troughshaped form by subsequent movements.

animals analogous in structure to the frog; as the
Salamander.

(from belemnon, a dart), fossil internal shell of an
extinct genus of cuttle-fish.
divided in two parts, or forked.

divided into two lobes.

mineral pitch or tar.

belonging to the arm.

molluscous animals that have arm-like processes. aquatic organs of respiration, as gills. conglomerate of fragments of rocks.

moss-animals; a group of marine animals, as the Flustræ.

deposition from thermal springs charged with carbonate of lime.

a tertiary limestone of the Paris basin.

composed of lime.

metallic base of lime.

a bryozoan with bell-shaped cells.

the cellular structure of a bone.

a little box or other containing cavity, a botanical term.

the elementary substance of charcoal, coal, and the diamond.

lime and carbonic acid.

belonging to coal.
fleshy.

a clove-like coral.

belonging to the tail.

a force directed from the centre to the circumfer

ence.

belonging to the head.

animals having the instruments of motion placed around the head; as the Cuttle-fish.

belonging to the neck.

marine mammalia, as the Whale, Porpoise, &c.
a species of silex, named from Chalcedon, a city of
Asia, near which it is found in great abundance.
pincer-claws.

animals of the turtle tribe.

a silicious mineral allied to flint and chalcedony.
a zoophyte of the chalk.

curled processes, as in the Barnacle.
hair-like vibratory organs.

club-shaped.

the system of divisional planes in which crystals may be cleaved; the laminated structure in slate-rocks. insects having wing-cases, as Beetles.

shell-like.

a coalition of separate particles.

an articulating surface or joint.

applied to parallel strata lying upon each other.
pebbles or waterworn fragments cemented together,
as in Puddingstone.

trees bearing cones, as the Fir, Pine, &c.
heart-shaped.

a coarse shelly limestone of the oolite.
bark-bearing.

seed-lobes of plants.

a term applied in Suffolk to certain tertiary beds

of sand and shells.

the vent of a volcano.

having the form of a crater.

notched, or toothed.

belonging to chalk.

lily-shaped animals.

signifying the emergence of a stratum on the surface.

in form of a cross.

animals having an external crust or skeleton, as the Crab.

plants with concealed fructification, as Mosses, Ferns, &c.

presenting the structure of crystals.

symmetrical forms assumed by mineral substances.
coppery.
copper-bearing.
cup-shaped.

a family of plants, including Zamia and Cycas.

the ruins or detritus of rocks and strata, or the fragments of shells, &c.

parts which are shed, as leaves of trees; botanically, having the habit of shedding.

alluvial deposits formed at the mouths of rivers. tree-like; branched like a tree.

the removal of strata by the action of water, so as to expose the rocks beneath, as in the Wealden of the S.E. of England.

belonging to the skin.

the act of drying.

disintegrated materials of rocks.

plants with seeds having two lobes.

a marsupial animal, allied to the opossum.

deluge; a term employed to designate ancient alluvial deposits.

the inclination of strata.

insects having two wings.
in the form of a disk.

crystalline magnesian limestone.

the cavities in minerals, lined with minute crystals; as, for example, drusy-quartz in the hollows of flint-nodules.

an intruded vein of melted matter into rents or fissures of rocks.

that portion of the solid surface of the earth which is accessible to human observation.

animals having a prickly external integument, as the Starfish, Sea-Urchin, &c.

sea-urchin.

toothless; animals having no front teeth, as the Armadillo.

wing-cases of insects.

a genus of lily-shaped animals.

a large family of the crustaceans, including the Trilobites, Cyprides, &c.

dawn of the recent period; the early tertiary strata. the creature of a day.

worn away.

a steep side of a hill or mountain-chain. sheddings of animals and plants, or their relics.

interruption of the continuity of strata with displacement.

a French term for tertiary strata analogous to the Crag.

the zoology of a particular country.

a mineral which enters into the composition of
many crystalline rocks.

belonging to or composed of felspar.
impregnated with iron.

the botany of a particular country.
belonging to a river.

partly of fluviatile, and partly of marine origin.
leaf-like or leafy.

a division of animalcules having perforated shells.
a group, or series of strata, supposed to have been
formed during one geological period.
fossil-bearing.

spindle-shaped.

mollusks with the locomotive organs on the underpart of the body, as the Snail.

jelly-like.