Orthoceras

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Orthoceras \Or*thoc"e*ras\, n. [NL., fr. Gr. 'orqo`s straight +
     ke`ras 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.
     [1913 Webster]