118 
specimens). In full grown individuals the base, coste, and spines. 
are covered by a dense epitheca ; younger ones have the epitheca. 
thin and delicate. The calice is large, open, and scarcely 
concave; like the base it is hexagonal in outline, each angle 
being marked by the strong projection of a primary, and its two 
adjacent quinary septa. From the latter, the wall curves in- 
wards towards the secondaries, where there is another, but much 
smaller projection. 
The septa are in six systems, with five cycles; all extend 
beyond the wall in varying degrees, the primaries the most. In 
plan they exhibit the same pecularities as were noted by Moseley 
in the case of the recent S. nobilis. The diagram given by him 
in the Challenger Report of a complete system in the recent form 
can, in fact, be cited as almost exactly representing the septal 
scheme of the fossil one. Of the four quaternaries in each 
system, the two nearest the primaries, besides being slightly 
thicker than the others, bend towards and join the tertiaries at 
from half to two-thirds from the wall ; each half system is, in 
fact, trisected by these two connected septa, so that the tertiaries 
are, according to the theoretical order of cyclical development, 
unsymmetrically placed. The quaternaries adjoining the 
secondaries are straight and free, and approximately equal to the 
quinaries. Only four of the latter are present in each system 
instead of eight, viz., between each pair of connected septa, and 
flanking the primaries; on either side of the free quaternaries 
they are absent. In the type calice, the bent quaternary and 
the quinary between it and the adjoining tertiary are wanting 
for half of one of the systems. The principal septa increase 
gradually in thickness according to order as they approach the 
wall, especially the primaries, which become very stout; beyond 
it they taper off rapidly. The higher orders are just slightly 
thickened at the wall. The primaries and the quinaries next 
them are very exsert at the margin of the calice, where, also, the 
latter are joined to the former by a prolongation of the wall. A 
similar union of the free quaternaries with the secondary septa 
is also noticeable. 
The costal tubercles proceeding from the base are really lateral 
continuations of the exsert primaries, and mark as it were the 
framework on which the coral is built ; together they give it a 
most characteristic appearance. For the most part the superior 
portions of the septa are broken off in the specimens, but from 
occasional intact ones still left, it is apparent that im life all of 
them rose as fan-shaped structures of varying height near the 
wall. The primaries, secondaries, tertiaries, and bent quater- 
naries are hollowed out, and deeply notched in their middle 
portions, and then rise again in one or more smaller elevations, 
