156 THE VOYAGE OF H.M.S. CHALLENGER. 



all the septa except the quiuaries, most marked on the tertiaries, very faint on the others. 

 As in Stephanotrochus discoides, only one pair of quaternary septa is well developed 

 in size in each system, and these are the quaternaries next the primaries, and they are 

 bent towards the tertiaries to fuse with them ; the two being nearly equal in size 

 divide each half-system into three nearly equal sections, the tertiary being, as it were, out 

 of place somewhat. The other pair of quaternaries in each system is small, looking like 

 a large quinary, and between it and the adjacent secondary the quinary septa are absent ; 

 there are only four quinaries developed in each system instead of eight. The quinaries 

 next the primaries rise as high in exsertion as the tertiaries, and are joined to the 

 primaries by prolongation of the wall ; to the secondaries are fused the exsert tips of the 

 little developed quaternaries next them, which rise to the same height also as the 

 tertiaries. The arrangement of the septa is shown in the preceding diagram. 



The tertiary, secondary, and primary septa extended nearly to the centre of the bottom 

 of the fossa ; their ends here are fused together, and connected in the centre by a very 

 small quantity of tortuous calcareous matter, the only representative of a columella. The 

 coral bears some resemblance to Turbinolia obcesa, Michelotti 1 (Trochocyathus obassvs, 

 M.-Edw. and H.), as figured, but the details available are not sufficient to determine if the 

 two forms have any real alliance. In Trochocyathus obcesits the pali are well developed. 



Height of the single specimen, to the margin of the calicle, 25 mm. ; to the lips of 

 the primary septa, 33 mm. Extreme breadth of the calicle, 33 mm. 



Station 73. Off the Azores. 1000 fathoms. 



Cyathoceras, n. gen. 



Corallum conical, elongate, without epitheca, or with a partial one only, fixed by a 

 stout pedicle, with a well developed fascicular columella. 



This genus is formed to receive two species which might be placed with Desmophyllum 

 if they had not columellas in every respect resembling those of the Caryojrfiyllias. 



Cyathoceras conm, n. sp. (PL IV. figs. 7, 7a). 



Corallum elongate, conical, attached by a stout base, with a few transverse irregular 

 constrictions or ridge-like marks at intervals, looking as if formed by a partial spontaneous 

 fracture and reuniting of the coral, or as marking succession of intervals in growth. 

 Costaa slightly marked near the margin of the calicle only. Surface slightly roughened, 

 or covered to a considerable extent with a thin glistening transparent epitheca. CaHcle 

 circular. Septa in six systems and four complete cycles, somewhat irregular, free from 

 attachment to one another, barely exsert, straight, except at the inner margins where 

 they are sinuous, with nearly smooth surfaces. Columella prominent in the fossa of the 

 calicle, slightly elongate, composed of four or five twisted laminae. 



1 Description des terraines Miocenes de l'ltalie septemtrionale, Leide, 1847, p. 22, pi. i. rigs. 21, 22. 



