166 THE VOYAGE OF H.M.S. CHALLENGER. 
tendency to be polygonal by the formation of angles opposite the primary and secondary 
coste. There are six systems of septa and four complete cycles. The primary septa are 
equal to the secondary, and the septa are quite symmetrical and regular in arrangement ; 
they are not exsert, but the margin of the calicle is slightly dentate. The septa are 
extremely delicate and thin, and though in their main course perfectly straight are, when 
carefully examined, seen to be finely wrinkled throughout. All the septa but the 
quaternaries are complete. The inner borders of the primary and secondary septa are 
perpendicular, and surround a very deep but narrow, elongate fossa, at the bottom of 
which is the columella, oval in outline, composed as usual in the genus of twisted out- 
erowths from the bases of the septa. 
This species is well distinguished by its simple conical form, the small extent to 
which it is compressed, and its extremely fragile structure. 
Height of the corallum, 29mm. Longer diameter of the calicle, 30 mm. Shorter 
diameter, 25 mm. 
Station 218. Lat. 2° 33’ S., long. 144° 4’ E. Off the Admiralty Islands. 1090 
fathoms. A single specimen only dredged. 
Flabellum patagonichum, n. sp. (PL XV. figs. 1-7 and 1la-7a). 
The corallum is attached when young, free when adult, conical, somewhat compressed, 
with smooth surfaces. The lateral borders of the corallum, which are simply rounded, are 
inclined to one another at an angle of about 75°,and the faces are inclined to one another 
in their middle lines about 55°. The surface is covered with a light-brown epitheca to 
very near the margin of the calicle. In all young specimens there is a distinct short 
pedicle. In some adult specimens this pedicle is still preserved, in others it is obliterated, 
and the cone ends with straight sides in a simple blunt point. The wall is marked with 
transverse wavy accretion lines. There are no coste, but in most of the specimens 
there occur shallow furrow-like depressions, formed by slight infoldings of the wall along 
the lines which might be occupied by the primary and secondary costa. 
The outline of the mouth of the calicle is oval, the summits of the short axis are very 
shghtly higher than those of the long axis. The margin of the calicle shows slight 
denticulations corresponding with the primary, secondary, and tertiary septa. There are 
six systems and four complete and regular cycles in all the specimens. The septa, which 
are very thin and straight, are usually slight red coloured, as is also the wall of the 
corallum where not invested with epitheca. The faces of the septa bear small pointed 
granules disposed in curved lines upon them. The primary and secondary septa only 
are complete, and are equal, the quaternary are very slightly prominent from the wall 
for the whole depth of the calicle. In many specimens the free margins of all the septa 
are irregularly serrate. 
The columella varies much in development. In some specimens it is represented by 
