Pachyscalpellum cramptoni, a new genus and species of lepadomorph cirripede, is described from the late Cretaceous (Haumurian) of Hawke's Bay, New Zealand. Pachyscalpellum is also recognized from the Santonian-Campanian of the Perth Basin, Western Australia. The genus is unusual in that, although the capitular valves are very much thickened, the tergum demonstrates negative allometric growth along its scutal margin. Pachyscalpellum is known only from shallow water marine facies, and the heavily calcified valves are interpreted as a defence against damage in this high energy environment.