Charles Darwin: The Origin of Species by means of Natural Selection

GLOSSARY 1. GLOSSARY OF THE PRINCIPAL SCIENTIFIC TERMS USED IN THE PRESENT VOLUME. (continued)

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 coloured.

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.