With 4 plates

The present report is based on three specimens of Prosobranchs from the southeast Asian waters. Two appear to represent each a species new to science, while the third specimen is assigned here with some doubt to a previously known species. One sample was collected by the Naval officer Land, and two samples were procured by D r. J. Verwey during his par-ticipation in the "Java-South Afr ica Expedition 1929-30 " organized by Dr. T h. Mortensen, Copenhagen. The material is kept in the Rijksmuseum van Natuurlijke Historie, Leiden, the Netherlands. I am greatly indebted to Dr. C. O. van Regteren Altena for entrusting the material to me for study and for useful information on the origin of the samples. The photographs were taken by M r. G. Brovad and the English text was revised by Miss Susan Thorpe. TROCHIDAE Calliostoma Swainso