166 THE VOYAGE OF H.M.S. CHALLENGES. 



tendency to be pergonal by the formation of angles opposite the primary and secondary 

 costse. 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- 

 growths 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, 29 mm. 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. 



FldbeUum patagonichum, n. sp. (PI. XV. figs. 1-7 and la-7«). 



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 costse, 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 costse. 



The outline of the mouth of the calicle is oval, the summits of the short axis are very 

 slightly 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 



