REPORT ON CORALS—DEEP-SEA MADREPORARIA. 151 
are very conspicuous and prominent, those of the third cycle being as usual the largest 
and projecting to a height of 4 mm. above the level of the summit of the columella, 
whilst those of the primary cycle are not elevated more than 1°5 mm. above that point. 
The tertiary pali are broad, the secondary and primary much narrower. The superior 
margins of all the pali are rounded. In some specimens all the pali are slightly indented 
on their inner edges. The pali of the secondary septa are placed at a slightly further 
distance outwards from the centre of the columella than those of the primary. The pali 
thus form three rings or crowns. Wherever a pair of septa of the partial fifth cycle are 
developed, the quaternary septa intervening between them are greatly enlarged, and 
occasionally fused with the adjoining tertiary septa. They are also provided with pali 
somewhat smaller than those of the tertiary cycle, and placed at a slightly further 
distance from the axis of the coral. The whole of the septa and pali are formed of thin 
but strong laminee slightly thickened at the line of origin from the calicle, and terminating 
superiorly in sharp knife-edged margins. The surfaces of the septa and pali are covered 
with very small granular projections, which on the primary and secondary septa are seen 
to be arranged with considerable regularity in rows, radiating from a point a little 
inferior to the point of junction of the septa with the margin of the calicle towards the 
margin of the septa, and marking out also a series of successive lines which follow the 
course of the margins of the septa, and are the lines of growth of the septa. Similar lines 
of growth are to be observed on the pali. The columella is about 4 mm. in breadth, and 
is composed of a number of contorted papillae covered with a fine granulation, and more 
or less fused into a single tubercular mass in old specimens. 
Diameter of calicle of smallest specimen 15 mm. Height, exclusive of conical 
tubercle on base, 8 mm. Diameter of calicle in largest specimen 27 mm. Extreme 
diameter of the same measured from the outer edges of the summits of the exsert septa 
32mm. Height of calicle 16 mm. ; measured to the top of the septa 20 mm. Diameter 
of base of calicle 21 mm., of circlet of basal spines 28 mm. 
Stephanotrochus, n. gen. 
Corallum dense and compact in substance, cup-shaped or saucer-shaped, with trace of 
early attachment, usually with well developed costee bearing a succession of small spines, 
with widely open capacious fossa. Septa usually extremely exsert, the exsert quinaries, 
or quaternaries where these are not present, lying next to the primaries, higher than 
the tertiaries, or equal to them. Columella absent or little prominent. 
I have formed this genus to contain four species of corals dredged by the Challenger 
which are evidently very closely allied, but for which it is nevertheless somewhat difficult 
to find generic characteristics in the terms of the ordinary designation of genera. I placed 
the four species provisionally in my Report on Corals in the genus Ceratotrochus. 
