GLOSSARY OF THE PRINCIPAL SCIENTIFIC TERMS USED IN THE PRESENT VOLUME.
(I am indebted to the kindness of Mr. W.S. Dallas for this Glossary, which
has been given because several readers have complained to me that some of
the terms used were unintelligible to them. Mr. Dallas has endeavoured to
give the explanations of the terms in as popular a form as possible.)
ABERRANT.—Forms or groups of animals or plants which deviate in
important characters from their nearest allies, so as not to be easily
included in the same group with them, are said to be aberrant.
ABERRATION (in Optics).—In the refraction of light by a convex lens
the rays passing through different parts of the lens are brought to a
focus at slightly different distances—this is called SPHERICAL
ABERRATION; at the same time the coloured rays are separated by the
prismatic action of the lens and likewise brought to a focus at different
distances—this is CHROMATIC ABERRATION.
ABNORMAL.—Contrary to the general rule.
ABORTED.—An organ is said to be aborted, when its development has
been arrested at a very early stage.
ALBINISM.—Albinos are animals in which the usual colouring matters
characteristic of the species have not been produced in the skin and its
appendages. Albinism is the state of being an albino.
ALGAE.—A class of plants including the ordinary sea-weeds and the
filamentous fresh-water weeds.
ALTERNATION OF GENERATIONS.—This term is applied to a peculiar mode
of reproduction which prevails among many of the lower animals, in which
the egg produces a living form quite different from its parent, but from
which the parent-form is reproduced by a process of budding, or by the
division of the substance of the first product of the egg.
AMMONITES.—A group of fossil, spiral, chambered shells, allied to
the existing pearly Nautilus, but having the partitions between the
chambers waved in complicated patterns at their junction with the outer
wall of the shell.
ANALOGY.—That resemblance of structures which depends upon
similarity of function, as in the wings of insects and birds. Such
structures are said to be ANALOGOUS, and to be ANALOGUES of each other.
ANIMALCULE.—A minute animal: generally applied to those visible only
by the microscope.
ANNELIDS.—A class of worms in which the surface of the body exhibits
a more or less distinct division into rings or segments, generally
provided with appendages for locomotion and with gills. It includes the
ordinary marine worms, the earth-worms, and the leeches.
ANTENNAE.—Jointed organs appended to the head in Insects, Crustacea
and Centipedes, and not belonging to the mouth.
ANTHERS.—The summits of the stamens of flowers, in which the pollen
or fertilising dust is produced.
APLACENTALIA, APLACENTATA or APLACENTAL MAMMALS.—See MAMMALIA.
ARCHETYPAL.—Of or belonging to the Archetype, or ideal primitive
form upon which all the beings of a group seem to be organised.
ARTICULATA.—A great division of the Animal Kingdom characterised
generally by having the surface of the body divided into rings called
segments, a greater or less number of which are furnished with jointed
legs (such as Insects, Crustaceans and Centipedes).
ASYMMETRICAL.—Having the two sides unlike.
ATROPHIED.—Arrested in development at a very early stage.
BALANUS.—The genus including the common Acorn-shells which live in
abundance on the rocks of the sea-coast.
BATRACHIANS.—A class of animals allied to the Reptiles, but
undergoing a peculiar metamorphosis, in which the young animal is
generally aquatic and breathes by gills. (Examples, Frogs, Toads, and
BOULDERS.—Large transported blocks of stone generally embedded in
clays or gravels.
BRACHIOPODA.—A class of marine Mollusca, or soft-bodied animals,
furnished with a bivalve shell, attached to submarine objects by a stalk
which passes through an aperture in one of the valves, and furnished with
fringed arms, by the action of which food is carried to the mouth.
BRANCHIAE.—Gills or organs for respiration in water.
BRANCHIAL.—Pertaining to gills or branchiae.
CAMBRIAN SYSTEM.—A series of very ancient Palaeozoic rocks, between
the Laurentian and the Silurian. Until recently these were regarded as the
oldest fossiliferous rocks.
CANIDAE.—The Dog-family, including the Dog, Wolf, Fox, Jackal, etc.
CARAPACE.—The shell enveloping the anterior part of the body in
Crustaceans generally; applied also to the hard shelly pieces of the
CARBONIFEROUS.—This term is applied to the great formation which
includes, among other rocks, the coal-measures. It belongs to the oldest,
or Palaeozoic, system of formations.
CAUDAL.—Of or belonging to the tail.
CEPHALOPODS.—The highest class of the Mollusca, or soft-bodied
animals, characterised by having the mouth surrounded by a greater or less
number of fleshy arms or tentacles, which, in most living species, are
furnished with sucking-cups. (Examples, Cuttle-fish, Nautilus.)
CETACEA.—An order of Mammalia, including the Whales, Dolphins, etc.,
having the form of the body fish-like, the skin naked, and only the fore
CHELONIA.—An order of Reptiles including the Turtles, Tortoises,
CIRRIPEDES.—An order of Crustaceans including the Barnacles and
Acorn-shells. Their young resemble those of many other Crustaceans in
form; but when mature they are always attached to other objects, either
directly or by means of a stalk, and their bodies are enclosed by a
calcareous shell composed of several pieces, two of which can open to give
issue to a bunch of curled, jointed tentacles, which represent the limbs.
COCCUS.—The genus of Insects including the Cochineal. In these the
male is a minute, winged fly, and the female generally a motionless,
COCOON.—A case usually of silky material, in which insects are
frequently enveloped during the second or resting-stage (pupa) of their
existence. The term "cocoon-stage" is here used as equivalent to
COELOSPERMOUS.—A term applied to those fruits of the Umbelliferae
which have the seed hollowed on the inner face.
COLEOPTERA.—Beetles, an order of Insects, having a biting mouth and
the first pair of wings more or less horny, forming sheaths for the second
pair, and usually meeting in a straight line down the middle of the back.
COLUMN.—A peculiar organ in the flowers of Orchids, in which the
stamens, style and stigma (or the reproductive parts) are united.
COMPOSITAE or COMPOSITOUS PLANTS.—Plants in which the inflorescence
consists of numerous small flowers (florets) brought together into a dense
head, the base of which is enclosed by a common envelope. (Examples, the
Daisy, Dandelion, etc.)
CONFERVAE.—The filamentous weeds of fresh water.
CONGLOMERATE.—A rock made up of fragments of rock or pebbles,
cemented together by some other material.
COROLLA.—The second envelope of a flower usually composed of
coloured, leaf-like organs (petals), which may be united by their edges
either in the basal part or throughout.
CORRELATION.—The normal coincidence of one phenomenon, character,
etc., with another.
CORYMB.—A bunch of flowers in which those springing from the lower
part of the flower stalks are supported on long stalks so as to be nearly
on a level with the upper ones.
COTYLEDONS.—The first or seed-leaves of plants.
CRUSTACEANS.—A class of articulated animals, having the skin of the
body generally more or less hardened by the deposition of calcareous
matter, breathing by means of gills. (Examples, Crab, Lobster, Shrimp,
CURCULIO.—The old generic term for the Beetles known as Weevils,
characterised by their four-jointed feet, and by the head being produced
into a sort of beak, upon the sides of which the antennae are inserted.
CUTANEOUS.—Of or belonging to the skin.
DEGRADATION.—The wearing down of land by the action of the sea or of
DENUDATION.—The wearing away of the surface of the land by water.
DEVONIAN SYSTEM or FORMATION.—A series of Palaeozoic rocks,
including the Old Red Sandstone.
DICOTYLEDONS, or DICOTYLEDONOUS PLANTS.—A class of plants
characterised by having two seed-leaves, by the formation of new wood
between the bark and the old wood (exogenous growth) and by the
reticulation of the veins of the leaves. The parts of the flowers are
generally in multiples of five.
DIFFERENTATION.—The separation or discrimination of parts or organs
which in simpler forms of life are more or less united.
DIMORPHIC.—Having two distinct forms.—DIMORPHISM is the
condition of the appearance of the same species under two dissimilar
DIOECIOUS.—Having the organs of the sexes upon distinct individuals.
DIORITE.—A peculiar form of Greenstone.
DORSAL.—Of or belonging to the back.
EDENTATA.—A peculiar order of Quadrupeds, characterised by the
absence of at least the middle incisor (front) teeth in both jaws.
(Examples, the Sloths and Armadillos.)
ELYTRA.—The hardened fore-wings of Beetles, serving as sheaths for
the membranous hind-wings, which constitute the true organs of flight.
EMBRYO.—The young animal undergoing development within the egg or
EMBRYOLOGY.—The study of the development of the embryo.
ENDEMIC.—Peculiar to a given locality.
ENTOMOSTRACA.—A division of the class Crustacea, having all the
segments of the body usually distinct, gills attached to the feet or
organs of the mouth, and the feet fringed with fine hairs. They are
generally of small size.
EOCENE.—The earliest of the three divisions of the Tertiary epoch of
geologists. Rocks of this age contain a small proportion of shells
identical with species now living.
EPHEMEROUS INSECTS.—Insects allied to the May-fly.
FAUNA.—The totality of the animals naturally inhabiting a certain
country or region, or which have lived during a given geological period.
FERAL.—Having become wild from a state of cultivation or
FLORA.—The totality of the plants growing naturally in a country, or
during a given geological period.
FLORETS.—Flowers imperfectly developed in some respects, and
collected into a dense spike or head, as in the Grasses, the Dandelion,
FOETAL.—Of or belonging to the foetus, or embryo in course of
FORAMINIFERA.—A class of animals of very low organisation and
generally of small size, having a jelly-like body, from the surface of
which delicate filaments can be given off and retracted for the prehension
of external objects, and having a calcareous or sandy shell, usually
divided into chambers and perforated with small apertures.
FOSSORIAL.—Having a faculty of digging. The Fossorial Hymenoptera
are a group of Wasp-like Insects, which burrow in sandy soil to make nests
for their young.
FRENUM (pl. FRENA).—A small band or fold of skin.
FUNGI (sing. FUNGUS).—A class of cellular plants, of which
Mushrooms, Toadstools, and Moulds, are familiar examples.
FURCULA.—The forked bone formed by the union of the collar-bones in
many birds, such as the common Fowl.
GALLINACEOUS BIRDS.—An order of birds of which the common Fowl,
Turkey, and Pheasant, are well-known examples.
GALLUS.—The genus of birds which includes the common Fowl.
GANGLION.—A swelling or knot from which nerves are given off as from
GANOID FISHES.—Fishes covered with peculiar enamelled bony scales.
Most of them are extinct.
GERMINAL VESICLE.—A minute vesicle in the eggs of animals, from
which the development of the embryo proceeds.
GLACIAL PERIOD.—A period of great cold and of enormous extension of
ice upon the surface of the earth. It is believed that glacial periods
have occurred repeatedly during the geological history of the earth, but
the term is generally applied to the close of the Tertiary epoch, when
nearly the whole of Europe was subjected to an arctic climate.
GLAND.—An organ which secretes or separates some peculiar product
from the blood or sap of animals or plants.
GLOTTIS.—The opening of the windpipe into the oesophagus or gullet.
GNEISS.—A rock approaching granite in composition, but more or less
laminated, and really produced by the alteration of a sedimentary deposit
after its consolidation.
GRALLATORES.—The so-called wading-birds (storks, cranes, snipes,
etc.), which are generally furnished with long legs, bare of feathers
above the heel, and have no membranes between the toes.
GRANITE.—A rock consisting essentially of crystals of felspar and
mica in a mass of quartz.
HABITAT.—The locality in which a plant or animal naturally lives.
HEMIPTERA.—An order or sub-order of insects, characterised by the
possession of a jointed beak or rostrum, and by having the fore-wings
horny in the basal portion and membranous at the extremity, where they
cross each other. This group includes the various species of bugs.
HERMAPHRODITE.—Possessing the organs of both sexes.
HOMOLOGY.—That relation between parts which results from their
development from corresponding embryonic parts, either in different
animals, as in the case of the arm of man, the fore-leg of a quadruped,
and the wing of a bird; or in the same individual, as in the case of the
fore and hind legs in quadrupeds, and the segments or rings and their
appendages of which the body of a worm, a centipede, etc., is composed.
The latter is called serial homology. The parts which stand in such a
relation to each other are said to be homologous, and one such part or
organ is called the homologue of the other. In different plants the parts
of the flower are homologous, and in general these parts are regarded as
homologous with leaves.
HOMOPTERA.—An order or sub-order of insects having (like the
Hemiptera) a jointed beak, but in which the fore-wings are either wholly
membranous or wholly leathery, The Cicadae, frog-hoppers, and Aphides, are
HYBRID.—The offspring of the union of two distinct species.
HYMENOPTERA.—An order of insects possessing biting jaws and usually
four membranous wings in which there are a few veins. Bees and wasps are
familiar examples of this group.
ICHNEUMONIDAE.—A family of hymenopterous insects, the members of
which lay their eggs in the bodies or eggs of other insects.
IMAGO.—The perfect (generally winged) reproductive state of an
INDIGENES.—The aboriginal animal or vegetable inhabitants of a
country or region.
INFLORESCENCE.—The mode of arrangement of the flowers of plants.
INFUSORIA.—A class of microscopic animalcules, so called from their
having originally been observed in infusions of vegetable matters. They
consist of a gelatinous material enclosed in a delicate membrane, the
whole or part of which is furnished with short vibrating hairs (called
cilia), by means of which the animalcules swim through the water or convey
the minute particles of their food to the orifice of the mouth.
INSECTIVOROUS.—Feeding on insects.
INVERTEBRATA, or INVERTEBRATE ANIMALS.—Those animals which do not
possess a backbone or spinal column.
LACUNAE.—Spaces left among the tissues in some of the lower animals
and serving in place of vessels for the circulation of the fluids of the
LAMELLATED.—Furnished with lamellae or little plates.
LARVA (pl. LARVAE).—The first condition of an insect at its issuing
from the egg, when it is usually in the form of a grub, caterpillar, or
LARYNX.—The upper part of the windpipe opening into the gullet.
LAURENTIAN.—A group of greatly altered and very ancient rocks, which
is greatly developed along the course of the St. Laurence, whence the
name. It is in these that the earliest known traces of organic bodies have
LEGUMINOSAE.—An order of plants represented by the common peas and
beans, having an irregular flower in which one petal stands up like a
wing, and the stamens and pistil are enclosed in a sheath formed by two
other petals. The fruit is a pod (or legume).
LEMURIDAE.—A group of four-handed animals, distinct from the monkeys
and approaching the insectivorous quadrupeds in some of their characters
and habits. Its members have the nostrils curved or twisted, and a claw
instead of a nail upon the first finger of the hind hands.
LEPIDOPTERA.—An order of insects, characterised by the possession of
a spiral proboscis, and of four large more or less scaly wings. It
includes the well-known butterflies and moths.
LITTORAL.—Inhabiting the seashore.
LOESS.—A marly deposit of recent (Post-Tertiary) date, which
occupies a great part of the valley of the Rhine.
MALACOSTRACA.—The higher division of the Crustacea, including the
ordinary crabs, lobsters, shrimps, etc., together with the woodlice and
MAMMALIA.—The highest class of animals, including the ordinary hairy
quadrupeds, the whales and man, and characterised by the production of
living young which are nourished after birth by milk from the teats
(MAMMAE, MAMMARY GLANDS) of the mother. A striking difference in embryonic
development has led to the division of this class into two great groups;
in one of these, when the embryo has attained a certain stage, a vascular
connection, called the PLACENTA, is formed between the embryo and the
mother; in the other this is wanting, and the young are produced in a very
incomplete state. The former, including the greater part of the class, are
called PLACENTAL MAMMALS; the latter, or APLACENTAL MAMMALS, include the
Marsupials and Monotremes (ORNITHORHYNCHUS).
MAMMIFEROUS.—Having mammae or teats (see MAMMALIA).
MANDIBLES.—in insects, the first or uppermost pair of jaws, which
are generally solid, horny, biting organs. In birds the term is applied to
both jaws with their horny coverings. In quadrupeds the mandible is
properly the lower jaw.
MARSUPIALS.—An order of Mammalia in which the young are born in a
very incomplete state of development, and carried by the mother, while
sucking, in a ventral pouch (marsupium), such as the kangaroos, opossums,
etc. (see MAMMALIA).
MAXILLAE.—in insects, the second or lower pair of jaws, which are
composed of several joints and furnished with peculiar jointed appendages
called palpi, or feelers.
MELANISM.—The opposite of albinism; an undue development of
colouring material in the skin and its appendages.
METAMORPHIC ROCKS.—Sedimentary rocks which have undergone
alteration, generally by the action of heat, subsequently to their
deposition and consolidation.
MOLLUSCA.—One of the great divisions of the animal kingdom,
including those animals which have a soft body, usually furnished with a
shell, and in which the nervous ganglia, or centres, present no definite
general arrangement. They are generally known under the denomination of
"shellfish"; the cuttle-fish, and the common snails, whelks, oysters,
mussels, and cockles, may serve as examples of them.
MONOCOTYLEDONS, or MONOCOTYLEDONOUS PLANTS.—Plants in which the seed
sends up only a single seed-leaf (or cotyledon); characterised by the
absence of consecutive layers of wood in the stem (endogenous growth), by
the veins of the leaves being generally straight, and by the parts of the
flowers being generally in multiples of three. (Examples, grasses, lilies,
orchids, palms, etc.)
MORAINES.—The accumulations of fragments of rock brought down by
MORPHOLOGY.—The law of form or structure independent of function.
MYSIS-STAGE.—A stage in the development of certain crustaceans
(prawns), in which they closely resemble the adults of a genus (Mysis)
belonging to a slightly lower group.
NATATORY.—Adapted for the purpose of swimming.
NAUPLIUS-FORM.—The earliest stage in the development of many
Crustacea, especially belonging to the lower groups. In this stage the
animal has a short body, with indistinct indications of a division into
segments, and three pairs of fringed limbs. This form of the common
fresh-water CYCLOPS was described as a distinct genus under the name of
NEURATION.—The arrangement of the veins or nervures in the wings of
NEUTERS.—Imperfectly developed females of certain social insects
(such as ants and bees), which perform all the labours of the community.
Hence, they are also called WORKERS.
NICTITATING MEMBRANE.—A semi-transparent membrane, which can be
drawn across the eye in birds and reptiles, either to moderate the effects
of a strong light or to sweep particles of dust, etc., from the surface of
OCELLI.—The simple eyes or stemmata of insects, usually situated on
the crown of the head between the great compound eyes.
OOLITIC.—A great series of secondary rocks, so called from the
texture of some of its members, which appear to be made up of a mass of
small EGG-LIKE calcareous bodies.
OPERCULUM.—A calcareous plate employed by many Molluscae to close
the aperture of their shell. The OPERCULAR VALVES of Cirripedes are those
which close the aperture of the shell.
ORBIT.—The bony cavity for the reception of the eye.
ORGANISM.—An organised being, whether plant or animal.
ORTHOSPERMOUS.—A term applied to those fruits of the Umbelliferae
which have the seed straight.
OSCULANT.—Forms or groups apparently intermediate between and
connecting other groups are said to be osculant.
OVARIUM or OVARY (in plants).—The lower part of the pistil or female
organ of the flower, containing the ovules or incipient seeds; by growth
after the other organs of the flower have fallen, it usually becomes
converted into the fruit.
OVULES (of plants).—The seeds in the earliest condition.
PACHYDERMS.—A group of Mammalia, so called from their thick skins,
and including the elephant, rhinoceros, hippopotamus, etc.
PALAEOZOIC.—The oldest system of fossiliferous rocks.
PALPI.—Jointed appendages to some of the organs of the mouth in
insects and Crustacea.
PAPILIONACEAE.—An order of plants (see LEGUMINOSAE), The flowers of
these plants are called PAPILIONACEOUS, or butterfly-like, from the
fancied resemblance of the expanded superior petals to the wings of a
PARASITE.—An animal or plant living upon or in, and at the expense
of, another organism.
PARTHENOGENESIS.—The production of living organisms from
unimpregnated eggs or seeds.
PEDUNCULATED.—Supported upon a stem or stalk. The pedunculated oak
has its acorns borne upon a footstool.
PELORIA or PELORISM.—The appearance of regularity of structure in
the flowers of plants which normally bear irregular flowers.
PELVIS.—The bony arch to which the hind limbs of vertebrate animals
PETALS.—The leaves of the corolla, or second circle of organs in a
flower. They are usually of delicate texture and brightly coloured.
PHYLLODINEOUS.—Having flattened, leaf-like twigs or leafstalks
instead of true leaves.
PIGMENT.—The colouring material produced generally in the
superficial parts of animals. The cells secreting it are called
PINNATE.—Bearing leaflets on each side of a central stalk.
PISTILS.—The female organs of a flower, which occupy a position in
the centre of the other floral organs. The pistil is generally divisible
into the ovary or germen, the style and the stigma.
PLACENTALIA, PLACENTATA.—or PLACENTAL MAMMALS, See MAMMALIA.
PLANTIGRADES.—Quadrupeds which walk upon the whole sole of the foot,
like the bears.
PLASTIC.—Readily capable of change.
PLEISTOCENE PERIOD.—The latest portion of the Tertiary epoch.
PLUMULE (in plants).—The minute bud between the seed-leaves of
PLUTONIC ROCKS.—Rocks supposed to have been produced by igneous
action in the depths of the earth.
POLLEN.—The male element in flowering plants; usually a fine dust
produced by the anthers, which, by contact with the stigma effects the
fecundation of the seeds. This impregnation is brought about by means of
tubes (POLLEN-TUBES) which issue from the pollen-grains adhering to the
stigma, and penetrate through the tissues until they reach the ovary.
POLYANDROUS (flowers).—Flowers having many stamens.
POLYGAMOUS PLANTS.—Plants in which some flowers are unisexual and
others hermaphrodite. The unisexual (male and female) flowers, may be on
the same or on different plants.
POLYMORPHIC.—Presenting many forms.
POLYZOARY.—The common structure formed by the cells of the Polyzoa,
such as the well-known seamats.
PREHENSILE.—Capable of grasping.
PREPOTENT.—Having a superiority of power.
PRIMARIES.—The feathers forming the tip of the wing of a bird, and
inserted upon that part which represents the hand of man.
PROCESSES.—Projecting portions of bones, usually for the attachment
of muscles, ligaments, etc.
PROPOLIS.—A resinous material collected by the hivebees from the
opening buds of various trees.
PROTOZOA.—The lowest great division of the animal kingdom. These
animals are composed of a gelatinous material, and show scarcely any trace
of distinct organs. The Infusoria, Foraminifera, and sponges, with some
other forms, belong to this division.
PUPA (pl. PUPAE).—The second stage in the development of an insect,
from which it emerges in the perfect (winged) reproductive form. In most
insects the PUPAL STAGE is passed in perfect repose. The CHRYSALIS is the
pupal state of butterflies.
RADICLE.—The minute root of an embryo plant.
RAMUS.—One half of the lower jaw in the Mammalia. The portion which
rises to articulate with the skull is called the ASCENDING RAMUS.
RANGE.—The extent of country over which a plant or animal is
naturally spread. RANGE IN TIME expresses the distribution of a species or
group through the fossiliferous beds of the earth's crust.
RETINA.—The delicate inner coat of the eye, formed by nervous
filaments spreading from the optic nerve, and serving for the perception
of the impressions produced by light.
RETROGRESSION.—Backward development. When an animal, as it
approaches maturity, becomes less perfectly organised than might be
expected from its early stages and known relationships, it is said to
undergo a RETROGRADE DEVELOPMENT or METAMORPHOSIS.
RHIZOPODS.—A class of lowly organised animals (Protozoa), having a
gelatinous body, the surface of which can be protruded in the form of
root-like processes or filaments, which serve for locomotion and the
prehension of food. The most important order is that of the Foraminifera.
RODENTS.—The gnawing Mammalia, such as the rats, rabbits, and
squirrels. They are especially characterised by the possession of a single
pair of chisel-like cutting teeth in each jaw, between which and the
grinding teeth there is a great gap.
RUBUS.—The bramble genus.
RUDIMENTARY.—Very imperfectly developed.
RUMINANTS.—The group of quadrupeds which ruminate or chew the cud,
such as oxen, sheep, and deer. They have divided hoofs, and are destitute
of front teeth in the upper jaw.
SACRAL.—Belonging to the sacrum, or the bone composed usually of two
or more united vertebrae to which the sides of the pelvis in vertebrate
animals are attached.
SARCODE.—The gelatinous material of which the bodies of the lowest
animals (Protozoa) are composed.
SCUTELLAE.—The horny plates with which the feet of birds are
generally more or less covered, especially in front.
SEDIMENTARY FORMATIONS.—Rocks deposited as sediments from water.
SEGMENTS.—The transverse rings of which the body of an articulate
animal or annelid is composed.
SEPALS.—The leaves or segments of the calyx, or outermost envelope
of an ordinary flower. They are usually green, but sometimes brightly
SERRATURES.—Teeth like those of a saw.
SESSILE.—Not supported on a stem or footstalk.
SILURIAN SYSTEM.—A very ancient system of fossiliferous rocks
belonging to the earlier part of the Palaeozoic series.
SPECIALISATION.—The setting apart of a particular organ for the
performance of a particular function.
SPINAL CORD.—The central portion of the nervous system in the
Vertebrata, which descends from the brain through the arches of the
vertebrae, and gives off nearly all the nerves to the various organs of
STAMENS.—The male organs of flowering plants, standing in a circle
within the petals. They usually consist of a filament and an anther, the
anther being the essential part in which the pollen, or fecundating dust,
STIGMA.—The apical portion of the pistil in flowering plants.
STIPULES.—Small leafy organs placed at the base of the footstalks of
the leaves in many plants.
STYLE.—The middle portion of the perfect pistil, which rises like a
column from the ovary and supports the stigma at its summit.
SUBCUTANEOUS.—Situated beneath the skin.
SUCTORIAL.—Adapted for sucking.
SUTURES (in the skull).—The lines of junction of the bones of which
the skull is composed.
TARSUS (pl. TARSI).—The jointed feet of articulate animals, such as
TELEOSTEAN FISHES.—Fishes of the kind familiar to us in the present
day, having the skeleton usually completely ossified and the scales horny.
TENTACULA or TENTACLES.—Delicate fleshy organs of prehension or
touch possessed by many of the lower animals.
TERTIARY.—The latest geological epoch, immediately preceding the
establishment of the present order of things.
TRACHEA.—The windpipe or passage for the admission of air to the
TRIDACTYLE.—Three-fingered, or composed of three movable parts
attached to a common base.
TRILOBITES.—A peculiar group of extinct crustaceans, somewhat
resembling the woodlice in external form, and, like some of them, capable
of rolling themselves up into a ball. Their remains are found only in the
Palaeozoic rocks, and most abundantly in those of Silurian age.
TRIMORPHIC.—Presenting three distinct forms.
UMBELLIFERAE.—An order of plants in which the flowers, which contain
five stamens and a pistil with two styles, are supported upon footstalks
which spring from the top of the flower stem and spread out like the wires
of an umbrella, so as to bring all the flowers in the same head (UMBEL)
nearly to the same level. (Examples, parsley and carrot.)
UNICELLULAR.—Consisting of a single cell.
VERMIFORM.—Like a worm.
VERTEBRATA or VERTEBRATE ANIMALS.—The highest division of the animal
kingdom, so called from the presence in most cases of a backbone composed
of numerous joints or VERTEBRAE, which constitutes the centre of the
skeleton and at the same time supports and protects the central parts of
the nervous system.
WHORLS.—The circles or spiral lines in which the parts of plants are
arranged upon the axis of growth.
ZOEA-STAGE.—The earliest stage in the development of many of the
higher Crustacea, so called from the name of ZOEA applied to these young
animals when they were supposed to constitute a peculiar genus.
ZOOIDS.—In many of the lower animals (such as the Corals, Medusae,
etc.) reproduction takes place in two ways, namely, by means of eggs and
by a process of budding with or without separation from the parent of the
product of the latter, which is often very different from that of the egg.
The individuality of the species is represented by the whole of the form
produced between two sexual reproductions; and these forms, which are
apparently individual animals, have been called ZOOIDE.