Trentepohlia Jolithus, (L.) Wallr. (Chroolepus Jolithus, Ag.), an alga belonging to the family Chroolepidaceae, has a strong odor reminding of violets. Hence it is called, though not quite correctly, Veilchenmoos. In the fresh condition, the plant constitutes reddish-brown, when dry, grayish-green, thin felty coatings on rocks. Hence the name Veilchenstein applied to it e. g. in the German "Giant Mountains" or Riesengebirge. Upon distillation with water vapor, M. Bamberger and A. Landsiedl1) obtained a yellow volatile oil which possesses the characteristic odor of the plant.