Historians and geographers have been content merely to observe that at some periods, or on some particular maps, much of the continental space has been filled with drawings of land animals and the oceans frequently filled with sea monsters. The geographer attributes this to the desire for decoration or to fill in otherwise blank spaces of unknown continents and usually dismisses "those mythical monsters" without further comment.Disregard of unfamiliar animals has a long tradition. John de Marignolli commented in 1334: "and then poets have invented ypotamuses and plenty of other monsters" (Yule 1866). Swift"s well known quatrain finds a place repeatedly in the geography books. So Geographers in Afri-Maps With Savage-Pictures fill their Gaps And o"re unhabitable Downs Place Elephants for want of Towns.The pictorial element can be carried to an extreme and in many medieval maps the symbols become so utterly pictorial that they were used not only to represent the known but to mask the unknown.