\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.