of man; for the cases usually cited relate to the crossing of mules with individuals of pure species, and not to the intermixture of hybrid with hybrid.

6thly. From the above considerations, it appears that species have a real existence in nature; and that each was endowed, at the time of its creation, with the attributes and organization by which it is now distinguished.

GLOSSARY

OF

GEOLOGICAL AND OTHER SCIENTIFIC TERMS

USED IN THIS WORK.

ACEPHALOUS. The Acephala are that division of molluscous animals which, like the oyster and scallop, are without heads. The class Acephala of Cuvier comprehends many genera of animals with bivalve shells, and a few which are devoid of shells. Etym., a, a, without, and xspaλn, cephale, the head.

ADIPOCIRE. A substance apparently intermediate between fat and wax, into which dead animal matter is converted when buried in the earth, and in a certain stage of decomposition. Etym., adeps, fat, and cera, wax.

ALBITE. See "Felspar."

ALEMBIC. An apparatus for distilling.

ALGE. An order of division of the cryptogamic class of plants. The whole of the sea-weeds are comprehended under this division, and the application of the term in this work is to marine plants. Etym., alga, sea-weed.

ALLUVIAL. The adjective of alluvium, which see.

ALLUVION. Synonymous with alluvium, which see.

ALLUVIUM. Earth, sand, gravel, stones, and other transported matter which has been washed away and thrown down by rivers, floods, or other causes, upon land not permanently submerged beneath the waters of lakes or seas. Etym., alluo, to wash upon. For a further explanation of the term as used in this work, see Vol. II., pp. 122, 123. 298.

1

ALUM-STONE, ALUMEN, ALUMINOUS. Alum is the base of pure clay, and strata of clay are often met with containing much iron pyrites. When the latter substance decomposes, sulphuric acid is produced, which unites with the aluminous earth of the clay to form sulphate of alumine, or common alum. Where manufactories are established for obtaining the alum, the indurated beds of clay employed are called Alum-stone. AMMONITE. An extinct and very numerous genus of the order of molluscous animals called Cephalopoda, allied to the modern genus Nautilus, which inhabited a chambered shell, curved like a coiled snake. Species of it are found in all geological periods of the secondary strata; but they have not been seen in the tertiary beds. They are named from their resemblance to the horns on the statutes of Jupiter Ammon.

AMORPHOUS. Bodies devoid of regular form. Etym., a, a, without, and opon, morphe, form.

AMYGDALOID. One of the forms of the trap-rocks, in which agates and simple minerals appear to be scattered like almonds in a cake. Etym., auvysaza, amygdala, an almond.

VOL. I.-3 R

ANALCIME. A simple mineral of the Zeolite family, also called Cubizite, of frequent occurrence in the trap-rocks.

ANALOGUE. A body that resembles or corresponds with another body. A recent shell of the same species as a fossil-shell is the anologue of the latter. ANOPLOTHERE, ANOPLOTHERIUM. A fossil extinct quadruped belonging to the order Pachydermata, resembling a pig. It has received its name because the animal must have been singularly wanting in means of defence, from the form of its teeth and the absence of claws, hoofs, and horns. Etym., avowλes, anoplos, unarmed, and Inpior, therion, a wild beast.

ANTAGONIST POWERS. Two powers in nature, the action of the one counteracting that of the other, by which a kind of equilibrium or balance is maintained, and the destructive effect prevented that would be produced by one operating without a check.

ANTENNE. The articulated horns with which the heads of insects are invariably furnished.

ANTHRACITE. A shining substance like black-lead; a species of mineral charcoal.
Etym., avopa, anthrax, coal,
ANTHRACOTHERIUM. A name given to an extinct quadruped, supposed to belong to

the Pachydermata, the bones of which were found in lignite and coal of the tertiary strata. Etym., avopak, anthrax, coal, and Inpiov, therion, wild beast. ANTHROPOMORPHOUS. Having a form resembling the human. Etym., avůpææes, anthropos, a man, and μopon, morphe, form.

ANTICLINAL AXIS. If a range of hills, or a valley, be composed of strata, which on the two sides dip in opposite directions, the imaginary line that lies between them, towards which the strata on each side rise, is called the anticlinal axis. In a row of houses with steep roofs facing the south, the slates represent inclined strata, dipping north and south, and the ridge is an east and west anticlinal axis. In the accompanying diagram, a, a, are the anticlinal, and b, b, the synclinal lines. Etym., avrı, anti, against, and xxv, clino, to incline.

ANTISEPTIC. Substances which prevent corruption in animal and vegetable matter, as common salt does, are said to be antiseptic. Etym., avi, against, and onw, sepo, to putrefy.

ARENACEOUS. Sandy. Etym., arena, sand.

ARGILLACEOUS. Clayey, composed of clay. Etym., argilla, clay.

ARRAGONITE. A simple mineral, a variety of carbonate of lime, so called from having been first found in Arragon, in Spain.

AUGITE. A simple mineral of a dark green, or black colour, which forms a constituent part of many varieties of volcanic rocks. Name applied by Pliny to a particular mineral, from the Grek dvyn, auge, lustre.

AVALANCHES. Masses of snow which, being detached from great heights in the Alps, acquire enormous bulk by fresh accumulations as they descend; and when they fall into the valleys below, often cause great destruction. They are also called lavanges, and lavanches, in the dialects of Switzerland.

BASALT. One of the most common varieties of the Trap-rocks. It is a dark green or black stone, composed of augite and felspar, very compact in texture, and of

considerable hardness, often found in regular pillars of three or more sides, called basaltic columns. Remarkable examples of this kind are seen at the Giant's Causeway, in Ireland, and at Fingal's Cave, in Staffa, one of the Hebrides. The term is used by Pliny, and is said to come from basal, an Æthiopian word signifying iron. The rock often contains much iron.

"BASIN" of Paris, "BASIN" of London. Deposits lying in a hollow or trough, formed of older rocks; sometimes used in geology almost synonymously with "formations," to express the deposits lying in a certain cavity or depression in older rocks.

BELEMNITE. An extinct genus of the order of molluscous animals called Cephalopoda, having a long, straight, and chambered conical shell. Etym., Bexeuvov, belemnon, a dart.

BITUMEN. Mineral pitch, of which the tar-like substance which is often seen to ooze out of the Newcastle coal when on the fire, and which makes it cake, is a good example. Etym., bitumen, pitch.

BITUMINOUS SHALE. An argillaceous shale, much impregnated with bitumen, which is very common in the coal measures.

BLENDE. A metallic ore, a compound of the metal zinc with sulphur. It is often found in brown shining crystals; hence its name among the German miners, from the word blenden, to dazzle.

BLUFFS. High banks presenting a precipitous front to the sea or a river. A term used in the United States of North America.

BOTRYOIDAL. Resembling a bunch of grapes. Etym., Borpus, botrys, a bunch of grapes, and fos, eidos, form.

BOULDERS. A provincial term for large rounded blocks of stone lying on the surface of the ground, or sometimes imbedded in loose soil, different in composition from the rocks in their vicinity, and which have been therefore transported from a distance.

BRECCIA. A rock composed of angular fragments connected together by lime or other mineral substance. An Italian term.

CALC SINTER. A German name for the deposits from springs holding carbonate of lime in solution-petrifying springs. Etym., kalk, lime, sintern, to drop. CALCAIRE GROSSIER. An extensive stratum, or rather series of strata, found in the Paris Basin, belonging to the Eocene tertiary period. See Table I., E, Vol. II. p. 453. Etym., calcaire, limestone, and grossier, coarse.

CALCAREOUS ROCK. Limestone. Etym., calz, lime.

CALCAREOUS SPAR. Crystallized carbonate of lime.

CALCEDONY. A siliceous simple mineral, uncrystallized. Agates are partly composed of calcedony.

CARBON. An undecomposed inflammable substance, one of the simple elementary bodies. Charcoal is almost entirely composed of it. Etym., carbo, coal. CARBONATE of LIME. Lime combines with great avidity with carbonic acid, a gaseous acid only obtained fluid when united with water, and all combinations of it with other substances are called Carbonates. All limestones are carbonates of lime, and quick lime is obtained by driving off the carbonic acid by heat. CARBONATED SPRINGS. Springs of water, containing carbonic acid gas. They are very common, especially in volcanic countries; and sometimes contain so much gas, that if a little sugar be thrown into the water it effervesces like soda-water. CARBONIC ACID GAS. A natural gas which often issues from the ground, especially in volcanic countries. Etym., carbo, coal; because the gas is obtained by the slow burning of charcoal.

CARBONIFEROUS. A term usually applied, in a technical sense, to an ancient group

of secondary strata (see Table I., M, Vol. II. p. 456); but any bed containing coal may be said to be carboniferous. Etym., carbo, coal, and fero, to bear. CATACLYSM. A deluge. Etym., xaranλvo, catacluzo, to deluge.

CEPHALOPODA. A class of molluscous animals, having their organs of motion

arranged round their head. Etym., xso1^n, cephale, head, and wida, poda, feet. CETACEA. An order of vertebrated mammiferous animals inhabiting the sea. The whale, dolphin, and narwal are examples. Etym., cete, whale.

CHALK. A white earthy limestone, the uppermost of the secondary series of strata. See Table I., F, Vol. II., p. 454.

CHERT. A siliceous mineral, nearly allied to calcedony and flint, but less homogeneous and simple in texture. A gradual passage from chert to limestone is not

uncommon.

CHLORITIC SAND. Sand coloured green by an admixture of the simple mineral chlorite. Etym., xλapos, chloros, green. CLEAVAGE. Certain rocks, usually called slate rocks, may be cleaved into an indefinite number of thin lamine which are parallel to each other, but which are generally not parallel to the planes of the true strata or layers of deposition. The planes of cleavage, therefore, are distinguishable from those of stratification; and they also differ from joints, which are fissures or lines of parting, at definite distances, and often at right angles to the planes of stratification. The partings which divide columnar basalt into prisms are joints. The masses of rock included between joints cannot be cleaved into an indefinite number of laminæ or slates, having their planes of cleavage parallel to the joints. See first part of Chap. xxvii. Book IV., Vol. II.

CLINKSTONE, called also phonolite, a felspathic rock of the trap family, usually fissile. It is sonorous when struck with a hammer, whence its name. COAL FORMATION. This term is generally understood to mean the same as the Coal Measures. See Table I., M, Vol. 11. p. 456. There are, however, "coal formations" in all the geological periods, wherever any of the varieties of coal forms a principal constituent part of a group of strata.

COLEOPTERA. An order of insects (Beetles) which have four wings, the upper pair being crustaceous and forming a shield. Etym., xoxeos, coleos, a sheath, and Tepov, pteron, a wing.

CONFORMABLE. When the planes of one set of strata are generally parallel to those of another set which are in contact, they are said to be conformable. Thus the set a, b, Fig. 139., Vol. II. p. 343, rest conformably on the inferior set c, d ; but c, d rest unconformably on E.

CONGENERS. Species which belong to the same genus.
CONGLOMERATE OR PUDDINGSTONE, Rounded water-worn fragments of rock or

pebbles, cemented together by another mineral substance, which may be of a
siliceous, calcareous, or argillaceous nature. Etym., con, together, glomero, to
heap.

CONIFERE. An order of plants which, like the fir and pine, bear cones or tops in which the seeds are contained. Etym., conus, cone, and fero, to bear. COOMB. A provincial name in different parts of England for a valley on the declivity of a hill, and which is generally without water.

CORNBRASH. A rubbly limestone, forming a soil extensively cultivated in Wiltshire

for the growth of corn. It is a provincial term adopted by Smith. Brash is derived from brecan, Saxon, to break. See Table I., H, Vol. II. p. 454. CORNSTONE. A provincial name for a red limestone, forming a subordinate bed in the Old Red Sandstone group.

COSMOGONY, COSMOLOGY. Words synonymous in meaning, applied to speculations