554 Mr. H. N. Moseley on the true 



nambuco, Brazil, in 675 fathoms. It was without soft parts, but only 



recently dead. 



Ceratotrochus platypus, sp. n. 



The corallum is shallow and circular, with a wide horizontal base, from 

 which the low calicular wall rises abruptly and almost vertically. A 

 rudimentary peduncle is present attached to a small spiral shell, which, 

 together with the peduncle, becomes buried and obliterated in fully 

 grown specimens. Primary and secondary costse are slightly marked ; 

 they are simple, without teeth. There are six systems of septa and five 

 cycles. The quinary septa are incomplete. The septa are not fused 

 with one another. The primary and secondary septa are extremely 

 exsert. Well-marked pali are present on three of the septa of the larger 

 specimen ; otherwise pali are absent. The columella is rudimentary. 



Extreme diameters of two specimens 4-6 centims. and 3*5 centims. ; 

 extreme heights of the same 2*2 centims. and 1*9 centim. They were 

 procured together in lat. 34° 13' S., long. 151° 38' E., in 410 fathoms. 

 Both specimens had evidently been dead a long time. 



Ceratotrochus discoides, sp. n. 



This species resembles C. diadema, but is evidently specifically distinct. 

 The corallum is of the same shallow saucer- shape. The septa are less 

 exsert than in C. diadema, and there are only four cycles of septa, the 

 fourth cycle being imperfect. The secondary and tertiary septa are not 

 fused to one another. The columella is little developed, and made up 

 only of the fusion of the swollen inner ends of the septa ; it is ex- 

 cavated in its centre. A scar of attachment is present, and similar to 

 that in C. diadema. The costse are serrate. The diameter of the coral- 

 lum is 2-1 centims. The specimen is evidently adult. Only one speci- 

 men has been obtained, from 675 fathoms, lat. 8° 37' S., long. 34° 28' W., 

 off Pernambuco. 



Ceratotrochus nobilis, sp. n. 



This species differs from the three preceding in being deep aud cup- 

 shaped, the base being rounded, conical in form, and not flattened. A 

 scar of attachment is present. The costse are beset with short teeth. 

 The septa are exsert with rounded summits. There is no trace of pali. 

 Only one specimen has been obtained, 114 miles from Eayal, Azores, in 

 1000 fathoms. 



Note on the four Species of Ceratotrochus above described. 

 The four species of corals above described are evidently very closely 

 related to one another. In all the septa are remarkably exsert, in C. 

 platypus extraordinarily so. All show traces of original attachment, aud 

 are subpedicellate. In all but C. platypus the costse are armed with 

 short spines or teeth. In its general form C. platypus recalls Troclw- 

 cyathus coronatus, and it is remarkable that it shows a tendency to 



