THE outermost layer of the integument of insects is a complex structure known as the ‘epicuticle’, composed of several discrete layers the presence of which has been deduced by studying the permeability and deposition of the cuticle1. Homologous epicuticles have also been investigated in isopod and decapod Crustacea, and in ticks. Although earlier authors described an epicuticle in Myriapoda from staining reactions alone, such a structure has, in fact, not been satisfactorily demonstrated. The sclerotized layer containing phenolic substances in Tachypodoiulus, to which Hackman, Pryor and Todd refer2, is almost certainly exocuticle. The absence of a wax layer in the cuticle of millipedes has recently been demonstrated in Glomeris3, and in Paradesmus (unpublished), and it has been claimed that there is no epicuticle in the spider Tegenaria4.