170 THE VOYAGE OF H.M.S. CHALLENGER. 
lateral coste, and appear as irregularly dentate ridges separated by slight depressions. 
The calicle is compressed from side to side in the centre, so as to be narrowest there. 
Its upper margin is curved, describing about one-third of a circle. There are six systems 
of septa disposed in five cycles. The septa, which are extremely thin and fragile and 
covered with rounded granules, are disposed in rows. The primary septa approxi- 
mately equal to the secondary, giving somewhat the appearance of twelve systems. 
These septa are broad and prominent, with a rounded superior margin, and show curved 
lines of growth very distinctly. The septa of the third, fourth, and fifth cycles succes- 
sively diminish in breadth, and are thus very markedly distinguished from one another 
and from the primary and secondary septa. The quaternary septa join the tertiary a 
short distance before reaching the columella. The septa of the fifth cycle are incom- 
plete. The margin of the calicle is very deeply indented, the costa corresponding to 
the primary and secondary septa being prolonged in conjunction with the outer margins 
of those septa into prominent pointed processes. Similar but shorter costal prolongations 
accompany the tertiary septa and some of the quaternary. Between each of the sharp 
projections thus formed the edge of the wall of the calicle presents a curved indentation. 
The fossa of the calicle is extremely deep and capacious. The columella is elongate, with 
a nearly smooth surface formed of processes from the bases of the septa. All three perfect 
specimens obtained were of nearly the same size, and of closely similar form, being all 
pinched together towards the centre and showimg no tendency to broaden out there, nor 
to become irreeular or to split up into fragments. The two broken specimens are in 
form, as far as they go, precisely similar to the perfect ones. 
Judging apparently only from the woodcut given in Nature," and without having 
referred to my paper in the Proceedings of the Royal Society, Professor Lindstrém has 
placed this species with Flabellum laciniatum. He describes specimens dredged off the 
Azores in from 200 to 300 fathoms as agreeing with certain descriptions and figures 
given by Professor Martin Duncan and myself? I can see no resemblance between 
Professor Duncan’s figures cited by him and my own; nor can | think, after examining 
specimens of Flabellum laciniatum lent to me by Professor Duncan, that the two corals 
can be identical. I cannot, however, tell what amount of variation a long series of 
specimens might show. The large size, extreme lightness and fragility, and the peculiarly 
curved contours of the deep-sea form seem to be sufficient to separate it specifically, 
The Challenger specimens were obtained off the Azores also, but from a depth of 1000 
fathoms. 
With the adult corals were obtained two very small specimens, which seem 
almost certainly to be the young of the present species. They are in the form of small 
hexagonal columns slightly expanded above, and showing on each of the six faces a 
1 Nature, vol.viii. p. 400, 2 G. Lindstrém, Actinology of the Atlantic Ocean, p. 12. 
