The group of the Aradidae was largely made accessible by the excellent work of R. L. Usinger & R. Matsuda (Classification of the Aradidae, London 1959). It gave me the possibility of revising the collection of the Rijksmuseum van Natuurlijke Historie, from which already some species had been described by C. J. Drake and R. L. Usinger before. As a consequence of their ecology, the collecting of Aradidae is not very easy. The work done by the numerous collectors for our museum resulted in a medium-sized collection from a restricted number of localities, as in some cases the number of individuals in one capture is very high, and for the rest the captures are incidental only. A single remark may be made regarding the drawings in this paper. Many specimens offer a notable asymmetry; in those cases I have not symmetrized the figure by turning the half of it, as this often would have changed the total aspect. In one case, where the right side is hidden by incrustations and rubbish, the drawing shows the left side only. The data are given as found on the labels. Only in exceptional instances is the information translated into English, or the name of the locality transcribed. Again I am much indebted to the staff of the British Museum (Natural History), for assistance during my stay in the Hemiptera section. l SODERMINAE Isodermus gayi Spin. 1-3. Punta Arenas, Straits of Magellan, Walker, British Museum leg. Isodermus planus Er. 1-2. Van Diemensland, Klug. ARADINAE