Source : Webster's Revised Unabridged Dictionary (1913)

Graptolite \Grap"to*lite\, n. [NL, Graptolithus, from Gr. ? is
   engraved, written (gra`fein to write) + ? stone.] (Paleon.)
   One of numerous species of slender and delicate fossils, of
   the genus {Graptolites} and allied genera, found in the
   Silurian rocks. They belong to an extinct group
   ({Graptolithina}) supposed to be hydroids.