REPORT ON CORALS—DEEP-SEA MADREPORARIA. 157 
Height of the coralla, 15 mm. and 22 mm. respectively. Diameters of the calicles, 
10 mm. and 12 mm. 
Station 320, off the mouth of the Rio de la Plata. 600 fathoms. One specimen. 
Station 163, off Twofold Bay, New South Wales. 120 fathoms. One specimen. 
Cyathoceras rubescens, n. sp. (Pl. IL fig. 8, 8a, 8b, 8c). 
Corallum of a very pale reddish tint, white in places, elongate conical, curved, much 
compressed in its upper part, with a cylindrical stout pedicle terminating in an expanded 
and encrusting base. Surface glistening but slightly roughened. Costee more marked on 
one face than on the other, little prominent, except just at the margin of the calicle 
where all the exsert septa are continued a very short distance down the wall. Septa 
all exsert, with rounded edges; the quinary higher than the quarternary, and joined 
for nearly their entire height externally to the adjacent primaries, secondaries, and 
tertiaries, those next the tertiaries not so high as those next septa of higher order. 
Calicle elliptical in outline, with a deep fossa. Septa in six systems and five cycles, one 
pair of systems being incomplete in the only specimen. Septa free from attachment to one 
another, straight, with smooth surfaces, and slightly sinuous inner margins. Columella 
elongate in form, prominent in the fossa, composed of numerous more or less spirally 
twisted thin lamine. 
Height of the corallum, 35 mm. Breadth of the calicle, 23 mm. 
One perfect specimen, only attached to a dead fragment of another. 
Station 192, off the Ki Islands. 129 fathoms. 
Sphenotrochus. 
Sphenotrochus rubescens, Moseley (Pl. VI. fig. 8, 8a). 
Platytrochus rubescens, Moseley, Proc. Roy. Soc., 1876, p. 553. 
The corallum is of a light red colour. It is compressed and wedge-shaped, without 
trace of adherence, and provided with lateral aliform expansions derived from the lateral 
coste. The surface of the wall is roughened all over by the costz or their prolongations, 
and on the ale by transverse ridges. The whole of these ridges and costz are covered 
with minute sharp granules, so that the entire surface of the coral feels rough to the 
touch, like fine sand-paper. The costae commence as the continuations of the borders of 
the exsert septa, and are there prominent thin lamine. They gradually decrease in 
elevation towards the base, where they appear as small narrow ridges, which are some- 
what confused and interrupted here and there, though all converging in direction towards 
the apex of the coral cup. The primary and secondary coste are near the margin of 
the ecalicle, somewhat thicker than the others, but otherwise all the coste are equally 
developed and of an even height, except the two lateral ones, in three out of four 
specimens procured. In the fourth specimen the primary and secondary cost are a- 
