Dictionary entry

Orthoceras

Webster's Dictionary 1913

‖Or‐thoc″e‐ras (?), n. [NL., fr. Gr. ορθὄσ straight + κέρασ a horn.] (Paleon.) An extinct genus of Paleozoic Cephalopoda, having a long, straight, conical shell. The interior is divided into numerous chambers by transverse septa.