The rich material of Copepods collected by the Snellius Expedition in the seas of the Eastern part of the Malay Archipelago was placed at my disposal in 1943 by Prof. Dr. H. Boschma. The material proved to be very interesting and contained, besides new species, many rare forms found for the first time in the Indo-pacific area. A report on the families Calanidae, Eucalanidae, Paracalanidae, and Pseudocalanidae will be published in Temminckia, vol. VIII, pp. 1-181. A report on the family Aetideidae was completed in 1946 but, as the printing difficulties created by the war have not yet sufficiently improved to warrant the publication of this report within a short time, it seems desirable to publish a preliminary account of some new or interesting forms. Further particulars about the Aetideidae in the Snellius collections, along with notes on geographical and vertical distribution and complete synonymy of the species concerned will be published in the final report on the Aetideidae which, I hope, will be printed in the course of time. Full particulars about the various stations at which material was obtained during the Snellius Expedition may be found in Boschma (1936). As the material collected by the Siboga Expedition (vide A. Scott, 1909), present in the Zoölogisch Museum at Amsterdam, has now become available to me, the present paper also contains some information about Siboga specimens. A complete review of the Siboga Copepods, although much desired, is almost impossible as the specimens from the various stations have not been kept separately. Family AETIDEIDAE G. O. Sars, 1902 Genus Snelliaetideus nov. gen. Females. The head and the 1st thoracic segment are fused, the frontal