 Munthe was an active member of Geologiska föreningen i Stockholm being a longtime editor of its scientific journal "Geologiska föreningens förhandlingar" (now "GFF").He was also a member of the Swedish Society for Nature Conservation and Svenska Turistföreningen.Following his 1886 discovery of "Ancylus fluviatilis" fossils in Gotland in Munthe proposed in 1887 the existence of Ancylus Lake, a lake that would prove "the most enigmatic (and discussed) of the many Baltic stages".