笔石
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.