OCEANIC ridges show striking similarities to lunar wrinkle, or mare, ridges. The following points of comparison may be noted: (a) Both the terrestrial and lunar ridges are serpentine and furcate in places, (b) The smoothed form of the profiles of oceanic ridges1 and lunar wrinkle ridges2 is similar, (c) Central rifts characterizing parts of the oceanic system of ridges are also found in several mare ridges. The discovery of rifts capping the lunar ridges was made recently by Kuiper3 and further announcements have been made by me4 and by Arthur5. (d) In those instances where oceanic, and mare, ridges abut on the terrestrial, and lunar, continents, respectively, related lineaments continue the general trend for some distance into the continent in question, (e) Some of the terrestrial ridges terminate by wedging out and others end in major strike-slip faults6. Precisely these properties describe the terminal stages of lunar wrinkle ridges. For example, the furcating wrinkle ridge in Sinus Aestuum slices the Apennines in strike-slip faults as far as the ruined ring Marco Polo.