156 THE VOYAGE OF H.M.S. CHALLENGER. 
all the septa except the quinaries, most marked on the tertiaries, very faint on the others. 
As in Stephanotrochus discoides, only one pair of quaternary septa is well developed 
in size in each system, and these are the quaternaries next the primaries, and they are 
bent towards the tertiaries to fuse with them; the two being nearly equal in size 
divide each half-system into three nearly equal sections, the tertiary being, as it were, out 
of place somewhat. The other pair of quaternaries in each system is small, looking like 
a large quinary, and between it and the adjacent secondary the quinary septa are absent ; 
there are only four quinaries developed in each system instead of eight. The quinaries 
next the primaries rise as high in exsertion as the tertiaries, and are joined to the 
primaries by prolongation of the wall; to the secondaries are fused the exsert tips of the 
little developed quaternaries next them, which rise to the same height also as the 
tertiaries. The arrangement of the septa is shown in the preceding diagram. 
The tertiary, secondary, and primary septa extended nearly to the centre of the bottom 
of the fossa; their ends here are fused together, and connected in the centre by a very 
small quantity of tortuous calcareous matter, the only representative of a columella. The 
coral bears some resemblance to Turbinolia obesa, Michelotti’ (TLrochocyathus obesus, 
M.-Edw. and H.), as figured, but the details available are not sufficient to determine if the 
two forms have any real alliance. In Trochocyathus obesus the pali are well developed. 
Height of the single specimen, to the margin of the calicle, 25 mm.; to the lips of 
the primary septa, 33 mm. Extreme breadth of the calicle, 33 mm. 
Station 73. Off the Azores. 1000 fathoms. 
Cyathoceras, n. gen. 
Corallum conical, elongate, without epitheca, or with a partial one only, fixed by a 
stout pedicle, with a well developed fascicular columella. 
This genus is formed to receive two species which might be placed with Desmophylluin 
if they had not columellas in every respect resembling those of the Caryophyllias. 
Cyathoceras cornu, n. sp. (Pl. IV. figs. 7, 7a). 
lorallum elongate, conical, attached by a stout base, with a few transverse irregular 
constrictions or ridge-like marks at intervals, looking as if formed by a partial spontaneous 
fracture and reuniting of the coral, or as marking succession of intervals in growth. 
Coste slightly marked near the margin of the calicle only. Surface slightly roughened, 
or covered to a considerable extent with a thin glistening transparent epitheca. Calicle 
circular. Septa in six systems and four complete cycles, somewhat irregular, free from 
attachment to one another, barely exsert, straight, except at the inner margins where 
they are sinuous, with nearly smooth surfaces. Columella prominent in the fossa of the 
ralicle, shehtly elongate, composed of four or five twisted laminee. 
' Description des terraines Miocenes de l’'Italie septemtrionale, Leide, 1847, p. 22, pl. i. figs. 21, 22. 
