... In the Carina of Fossil Species of Scalpellum, I have found it necessary to distinguish different parts, viz., A, the tectum, of which half is seen; B, the parietes; and C, the intra-parietes. ... — A Monograph on the Sub-class Cirripedia (Volume 1 of 2) - The Lepadidae; or, Pedunculated Cirripedes • Charles Darwin