<jats:p> Two crystalline components isolated from the defensive secretion of the glomerid millipede, <jats:italic>Glomeris marginata</jats:italic> , are identified as 1-methyl-2-ethyl-4( 3 <jats:italic>H</jats:italic> )-quinazolinone and 1,2-dimethyl-4( 3 <jats:italic>H</jats:italic> )-quinazolinone. These heterocyclic compounds bear a close structural resemblance to arborine, the chief alkaloid of the Indian medicinal plant, <jats:italic>Glycomis arborea</jats:italic> Correa.