REPORT ON CORALS — DEEP-SEA MADREPORARIA. 153 



bending in towards them for the purpose at points somewhat further outwards ; the 

 quinary unite with the quaternary at a point still further distant, a condition thus 

 exists which is like that in Deltocyaihus and some Stephanophyllias. The disposition 

 of the septa is remarkably uniform in all the systems ; the columella is composed of 

 contorted finely fascicular matter, it is large and low, flat surfaced, and oval in superficial 

 outline. 



A mutilated specimen of what is apparently the young of the same species was 

 obtained on another occasion with the soft parts attached. The disc at the margin 

 of the calicle between the exsert septa was of a dark madder colour, and the same colour 

 was extended on the membrane, stretching thence over the base to the region where the 

 costal spines commence. Beyond this region the outer wall of the eorallum was bare and 

 not invested by living tissue. The remainder of the disc was of a pale bluish tint with a 

 zone of intensely dark madder colour round the mouth. The young eorallum is thinner 

 in texture, and flatter, and with the septa little exsert. 



Extreme diameters of the calicles 47 "5 mm. and 30 mm. respectively. Extreme 

 breadth between the exsert tips of the septa, 57'5 mm. and 36 mm. Vertical height of 

 the larger specimen to the margin of the calicle, 47*5 mm.; to the summits of the highest 

 septa, 2V5 mm. 



One large perfect specimen dredged at Station 120, off Pernambuco, Brazil. 675 

 fathoms. 



Mutilated young specimen. Station 78, off the Azores. 1009 fathoms. 



Stephanotrochus discoides, Moseley (PI. III., fig. 2, 2a, 2b, 2c). 

 Ceratotrochus discoides, Moseley, Proc. Roy. Soc, 1876, p. 554. 



The corallam is white and is saucer-shaped, but much flatter than in Stephanotrochus 

 diadema ; there is a short pedicle and small scar of attachment. The primary and second- 

 ary costse only are prominent, and bear each four or five short spines ; the primary and 

 secondary septa only are exsert, and these do not rise high above the margin of the calicle. 

 There are six systems, and only four cycles. The septa of the fourth cycle being only 

 partially developed in many of the systems, only two instead of four quaternaries being- 

 present in most of the systems, and these being those lying between the primary and 

 tertiary septa. These quaternary septa are bent towards the tertiaries to fuse with them. 

 The free borders of the septa are nearly straight, showing only an extremely slight indenta- 

 tion indicative of the paliform lobe seen in Stephanotrochus diadema. All the septa 

 except the quaternaries run straight towards the centre of the calicle. Their inner ends 

 are thickened and ddated, and, fusing together with the addition of some diffuse cementing 

 calcareous matter, form a sort of columella, the surface of which is excavated in the very 

 centre of the calicle by a well marked pit. 



From the denseness of its calcareous tissue and its general appearance, this Coral 



(ZOOL. CHALL. EXP. — PART VII. — 1880.) G 20 



