What is "calymene"

Calymene \Ca*lym"e*ne\, n. [Gr. (?) concealed, p. p. of ? to conceal.] (Zo["o]l.) A genus of trilobites characteristic of the Silurian age.

Calymene (meaning beautiful crescent as a reference to the glabella) is a genus of trilobites in the order Phacopida that are found throughout North America, North Africa, and Europe in primarily Silurian outcrops. Calymene is closely related to Flexicalymene, and both genera are frequently found inrolled. Calymene trilobites are small, typically 2 cm in length. Their cephalon is the widest part of the animal, and the thorax is usually in 13 segments.