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 forms.

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 womb.

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.

FELIDAE.--The Cat-family.

FERAL.--Having become wild from a state of cultivation or domestication.

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, etc.

FOETAL.--Of or belonging to the foetus, or embryo in course of
development.

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 c