i6 



exsert than those which immediately precede them. Those of the fourtli cycle usually unite 

 with those of the third some distance above the columella. 



The pali, which are lamellar and echinate, are about 30 in number and are placed 

 opposite all the septa except those of the last cycle. 



The columella, like that of Tropidocyathus lessoni^ to which species Trochocyathus pilats 

 is closely related, is very variable. In one specimen it consists of two rugose vertical plates 

 placed end to end, in another specimen it consists of a single regular row of teeth, in another 

 specimen it is a narrow spongiform mass, while in a fourth it consists of an elongate patch 

 of pinnacles not distinctly delimited from the pali. 



Greatest height of corallum of largest specimen 14 millim. 

 Major diameter of calicle 15 „ 



Minor „ „ „ 10 „ 



In general appearance this species has a c(3nsiderable likeness to Tropidocyathus /essoin' 

 without the wings. In the young stage this likeness is heightened by the presence of fairly prominent 

 lateral costse not unlike the wings of Tropidocj-athus in an incipient state. 



VIII. Subgenus Thecocyathus Edw. & H. 



Differs from TrocJiocyathtis in having the thecal wall surrounded, up to the calicular 

 margin, with an epitheca. 



The collection contains two species, of which one is represented by a dead and broken 

 specimen and is referred to this subgenus with some doubt. 



15. TrocJiocyathns (Thecocyathus) rhombocolumna n. sp. Plate II. Fig. 12. 



Stat. 95. 5°43'.5 N., ii9°40'E. 522 m. i Ex. dead and broken. 



The thecal wall is marked with fme transverse rugae, somewhat as in 'T. cinctictilatus 

 mihi. The septa and pali are strongly echinulate. 



Septa in six systems and four complete cycles -, the primaries are large and coarse, as also 

 are, but not to such a marked degree, the secondaries, both primaries and secondaries being 

 much more exsert than the septa of the lower cycles. None of the septa unite with one another. 



Pali lamellar, before all the septa except those of the last cycle ; those opposite the 

 tertiaries are much the largest. 



Columella formed of four large rugose prisms arranged in a rhomb. 



The unique specimen is dead and broken and is also the subject of a malformation on 

 one side, so that a completer diagnosis is not possible. 



16. TrocJiocyathiis (Tliecocyathns) z'irgatits n. sp. Plate II. Fig. 13. 



Stat. 105. 6°8'N., 121° 19' E. 275 m. i Ex. 



I Stat. 96, South-East of Pearl Bank, Sulu Archipelago. 15 m. i Ex.] 



This species has a very strong resemblance to Paracyathiis striatns Phil. {cf. Duncan, 



