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).

Having the two sides unlike.

Arrested in development at a very early stage.

The genus including the common Acorn-shells which live in abundance on the rocks of the seacoast.

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 Newts.)

Large transported blocks of stone generally embedded in clays or gravels.

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.

Gills or organs for respiration in water.

Pertaining to gills or branchiae.

A series of very ancient Palaeozoic rocks, between the Laurentian and the Silurian. Until recently these were regarded as the oldest fossiliferous rocks.

The Dog-family, including the Dog, Wolf, Fox, Jackal, etc.

The shell enveloping the anterior part of the body in Crustaceans generally; applied also to the hard shelly pieces of the Cirripedes.

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.