Corallum almost spherical, light, its base of attachment very small; 14 cm diameter, 11 cm high. Valleys long, meandering, almost straight in some regions; 10-12 mm wide, enlarged at heads to 15 mm or more, 10-15 mm deep. Collines thin, perforate, sharp edged.
Calicinal centers not very distinct but for deflection of nearby septa towards them; in single row within valley; occasionally joined by single lamella.
Septa 9-10 to a cm. Big septa with characteristic shape: upper third very narrow, vertical, its edge very finely dentate in some; middle portion widened into low arch, its edge subentire; lower portion (paliform lobe) expanded, its edge dropping vertically into bottom of valley, mostly deflected towards calicinal centers, usually cut into slender teeth. All septa equally thin, only slightly exsert over rim; surface finely granulate.
Columella absent, its site occupied by a loose mass of septal spines.
Costae (lower surface) prominent, regularly spaces, running from periphery to center of corallum. Both upper and lower surfaces heavily vesiculate.
This coral closely resembles Coeloria (?) gigantea (Plate 34, Fig. 3) of Yabe, Sugiyama and Eguchi but there are some marked differences in the description: My specimen has no, or at most, poorly developed columella so that the calicinal centers are not distinct; the septa are equally thin and not “definitely dentate” except at the paliform lobes of some. The heavy vesiculation is not mentioned by the Japanese workers.
The dimensions of the valleys and the collines and the characteristics of the septa and columellar centers are believed to justify the setting apart of this coral from Platygyra (Coeloria).
