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 vertebræ 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.
SCUTELLÆ.—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 Palæozoic series.