14+ THE VOYAGE OF H.M.S. CHALLENGER. 
slightly bent in the plane of compression. Near the margin of the calicle all the costa 
are well marked as slightly prominent thick ridges with rounded edges. The primary 
and secondary costee extend on one face of the corallum nearly to the base of the pedicle; 
on the other face, where they are less marked, they cease somewhat higher up. The 
tertiary and quaternary coste are much less developed than the others, and are well 
marked only close to the calicle; beneath they are indicated only by slight separating 
strie. The two lateral primary coste are thickened and prominent, but much less so 
than in other species of the genus; their edges are notched here and there irregularly ; 
the outline of the calicle is oval, very slightly angular at the ends of the oval. There 
are six systems of septa and four cycles ; twelve pali opposite the tertiaries. All the 
septa are exsert ; the exsert quaternaries are all higher than the tertiaries, and are fused 
externally to the side of the primaries and secondaries. The septa are straight, and their 
faces are almost smooth, bemg very sparsely covered with extremely minute spinules. 
The columella is elongate, and composed of thin twisted lamelle. 
The coral resembles Acanthocyathus gray: and Acanthocyathus spiniger in colour, 
and though the lateral spines are represented in it only by little developed laminz, there 
can be no doubt that it falls naturally within the genus Acanthocyathus. From 
Acanthocyathus grayi it differs in the more marked exsertness of its septa, and in 
these being slighter and smoother, also in the greater extent of the costee, further in the 
dulness of its surface, the surface in Acanthocyathus grayi being smooth and glistening. 
It resembles Acanthocyathus spiniger in the exsertness of its septa, but differs from 
it in being bent, and in the very small development of its alee, also in having the coste 
less sharply ridged, and only the primary and secondary at all prominent. 
Height of the corallum 17 mm. Long diameter of the calicle 18 mm., exclusive of 
the ale. Short diameter 13 mm. A single specimen only obtained. 
Station 210. Off the Philippine Islands, lat. 9° 26’ N., long. 123° 45’ E. 375 fathoms. 
Paracyathus. 
Paracyathus de filippii (Duch, and Mich.). 
Pourtalés, Il. Cat. Mus. Harvard, No. 8, p. 38. 
Paracyathus confertus, Pourtales, I. Cat. Mus. Harvard, No. 4, p. 11. 
Numerous specimens. Off Fayal Island, Azores. 50 fathoms. 
One specimen. Station 190. Arafura Sea. Lat. 8° 56’S., long. 136° 5’E. 49 fathoms. 
Heterocyathus. 
Fleterocyathus philippinensis, Semper. 
Numerous specimens. Off Malanipa Island, Southern Philippine Islands. 20 fathoms. 
? Ueher Generationswechsel bei Steinkorallen, Z. f. Wiss. Zool., Bd, xxii., 1872, s. 254. 
