Plate 33 from Rex Filson's The Lichens and Mosses of Mac.Roberston Land.

These paintings show two species of Umbilicaria, though in Filson's book the upper pair of figures was captioned as Omphalodiscus decussatus and the lower pair as Omphalodiscus antarcticus. Research has shown that the genus Omphalodiscus is identical with Umbilicaria, which has priority. The upper pair of figures would show Umbilicaria decussata, but determining the caption for the second pair of figures is not quite so straightforward and is discussed in the ANTARCTIC UMBILICARIA CASE STUDY.