A very ancient system of fossiliferous rocks belonging to the earlier part of the Palaeozoic series.
The setting apart of a particular organ for the performance of a particular function.
The central portion of the nervous system in the Vertebrata, which descends from the brain through the arches of the vertebrae, and gives off nearly all the nerves to the various organs of the body.
The male organs of flowering plants, standing in a circle within the petals. They usually consist of a filament and an anther, the anther being the essential part in which the pollen, or fecundating dust, is formed.
The breastbone.
The apical portion of the pistil in flowering plants.
Small leafy organs placed at the base of the footstalks of the leaves in many plants.
The middle portion of the perfect pistil, which rises like a column from the ovary and supports the stigma at its summit.
Situated beneath the skin.
Adapted for sucking.
(in the skull): The lines of junction of the bones of which the skull is composed.
( pl. Tarsi ): The jointed feet of articulate animals, such as insects.
Fishes of the kind familiar to us in the present day, having the skeleton usually completely ossified and the scales horny.