Note 8 — FLORA OF THE PRIMARY OR PALÆOZOIC PERIOD.
Reading edition
In giving names to fossil Ferns, the Greek word πτερίς, meaning a Fern, is often used with a prefix indicating some character in the form of the leaves, or stem, or fructification: such as, πέκος, a comb; νεῦρον, a nerve; ὀδούς, a tooth; σφήν, a wedge; καυλός, a stalk or stem; κύκλος, a circle; σχίζω, a split, etc.