In 1857 and 1860, Milne Edwards and Haime listed 9 species of Stylasterlna known to occur in the Pacific region, including "Allopora (Stylaster) infundibulifera", a species which later, as Amphelia infundibulifera (Lamarck), was to be classified in the Madreporaria (Scleractinia). Moseley (1880), who compiled a list of all the species of the group at that time known, recorded 22 species occurring in the Pacific region. To these Hickson & England (1905) added 14 new species, 4 new formae ("facies"), and 4 records of species up to that time not known from the Pacific; Fisher (1931, 1938) described 14 new species, 4 new subspecies, and 1 new forma ; Broch (1932, 1935, 1936, 1942) described 14 new species and 9 new formae. This brings the total of the species and forms known to occur in the Pacific up to 86. To these must be added the corals of the group described by various authors cited at the end of the present paper, which results in 127 Stylasterina of the Pacific regarded as separate species or formae. These are listed below, alphabetically in the different genera, each name followed by one or more numbers in brackets indicating the regions of the Pacific in which the species or formae are known to occur. The limits of the regions are more or less arbitrary, some might have been divided into smaller regions, others might have been combined to larger regions, but the here accepted regions on the whole appear to form a basis for the discussions in the following pages. The regions in which the Pacific area for the present purposes has been divided are: I, Alaska, Aleutian Islands, Bering Sea; 2, Okhotsk Sea; 3, Japan and adjacent seas; 4, Philippine Islands and Sulu Sea; 5, East Indian Archipelago; 6, New Guinea and Torres Strait; 7, Solomon Islands; 8, New