Emily Dickinson Lexicon

AR-GO-NAUT'A, n. [See Argonaut.]

A genus of shells, of the class Cephalopoda. The shell consists of one spiral involuted valve. The Argo, with a subdentated carina, is the famous nautilus, which, when it sails, extends two of its arms, spreading a membrane, which serves for a sail, and six other arms are thrown out, for rowing or steering. – Encyc. Cuvier.