TARSUS (pl. TARSI).—The jointed feet of articulate animals, such as insects.
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 lungs.
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 Palæozoic rocks, and most abundantly in those of Silurian age.
TRIMORPHIC.—Presenting three distinct forms.
UMBELLIFERÆ.—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.)