While studying the corals, collected by the Siboga-Expedition, I was impressed by the fact, that there is no agreement between different authors concerning the arrangement of the septa in the family Eupsammidae. According to the general law of VON KOCH a new septum is formed invariably between two older ones, and that simultaneously around the entire circumference of the calicle according their classification. Therefore the number of septa of a given order equals the total number of septa of all preceding orders. In the Eupsammidae we do not find this regularity. The septa belonging to the cycles of higher order are not all present. This irregularity has been a subject of study by different authors, the last of whom is VON MARENZELLER ¹).