The Collaborative International Dictionary of English v.0.48:

Cauda galli \Cau"da gal*li\, . [L., tail of a cock.] (Paleon.)
   A plume-shaped fossil, supposed to be a seaweed,
   characteristic of the lower Devonian rocks; as, the cauda
   galli grit.
   [1913 Webster]

   Cauda galli epoch (Geol.), an epoch at the begining of the
      Devonian age in eastern America, so named from the
      characteristic gritty sandstone marked with impressions of
      Cauda galli. See the Diagram under Geology.
      [1913 Webster]