Corallum caespitose, with small base, 5.3 cm high. Branches broad, flat, widening as they grow higher. One branch 22 x 12 mm at base; another 26 x 14 mm. Terminal diameters of same branches 32.5 x 11 mm; 28.5 x 16 mm respectively. Tips rounded, usually drawn out to produce branchlets.
Calicles crowded all over, deep, even with surface; fringed with tall, broad, flat spines, those on distal side slightly higher than those on proximal side in some calicles; spines generally standing across wall. Calicles somewhat polygonal, usually 1.2 mm diameter.
Primary septa very narrow at calicinal rim, widening towards columella at bottom of very deep fossa; in some calices the “six-toothed” arrangement evident, accentuated by exsertion of septa or by presence of prominent teeth on the septa near calicinal rim. Subsidiary septa recognizable in some calices as narrow ridges on wall, not reaching columella and not exsert over rim. In some calices, septa thickened and columella a wide mass so loculi small; in others with opposite features, loculi large, very deep.
Columella large or small, with single vertical blunt spine, prominent in some calices, not in others.
Intercalicinal areas very narrow, mostly occupied only by single row of flat spines. Where intercalicinal areas wider, very fine spines, almost like granules and much lower than flattened ones interspersed between rows of the latter.
This coral differs from S. mordax (Dana) by its very crowded calicles flush with the surface, and the nature of the intercalicinal spines.
Dana’s specimen figured by Vaughan (pl. 25) and U.S.N.M. specimen 44337 have very well marked “hoods”, the calices are not crowded, columella quite prominent, intercalicinal spines low but distinct.
