(L. ridge or summit): The mid-dorsal apex of the fourth ventricle that extends into the medullary substance of the cerebellum.

The anterior dorsal surface of the vertex on a grasshopper's head. (Figures)

(pl. fastigia, adj. fastigiate) ( Reitsma, 1966) Cavity in a colporate grain, appearing as a separation of the inner part of the exine from the domed sexine in the region of the endoaperture. Example: Hypericum (hypericaceae). Synonym of caverna. Comment: The term describes a feature morphologically similar to the vestibulum; the latter is restricted to porate pollen grains. See also: vestibulum.