ZOOLOGICAL AND BOTANICAL ASSOCIATION. 235 



gular ; the primaries and secondaries terminate at the shoulder in pro- 

 minent knobs. On the pedicel only the six primaries are distinguishable, 

 and these are then crossed by numerous strongly indented zigzag folds, 

 of which the higher angle is on the costa, the lower in the interspace. 

 All the costa) of the body -region are studded with irregularly projecting 

 points or papillary eminences. 



Base, a small but distinct circular cavity, into which the extremities 

 of the six primary costce project. 



Calice considerably arched, the short axis being much the higher. 



Fossula rather deep. 



Septa in three cycles, twenty-four in all; the lateral primaries 

 and secondaries more developed than the terminal ones; moderately 

 close-set, irregularly bent in their planes, thick exteriorly, suddenly 

 diminishing just within tho wall, and thence gradually becoming thinner. 

 The primaries and secondaries equal in height and breadth ; the ter- 

 tiaries much lower ; all exsert, the upper edge obliquely truncate, slop- 

 ing down from the margin inward. The two septa which form the short, 

 axis are united to the columella by diverging laminae ; but this structure 

 appears to be wanting in the others. The surfaces of all the septa are 

 rough, with scattered papillary points. 



Columella bent at each end towards one (the same) side ; its upper 

 edge thickened in irregular swellings. In some specimens it is not 

 visible from above. 



DIMENSIONS OF FOUR EXAMPLES. 



v„ Long Axis. Short Axis. Height 



wa Inch. Inch. Inch. 



1, 008 0062 0155 



2, (Fig. 1-3), 006 0042 0140 



8, (Fig. 4), 006 0050 / 0110 



4, 006 0422 0144 



This species resembles S. crispus in its zigzag folds, but has more 

 agreement with S. mixtus in its general characters. In its tendency to 

 a curved form, however, as well as in its pedicellate character ; and espe- 

 cially in the presence of a well-formed basal area, which appears to 

 have been a point of adhesion, it displays so much affinity with Cerato- 

 trochus (according to the diagnosis of M. Milne Edwards*) that I was 

 at first disposed to assign it to that genus. 



• " Brit Foes. Cor.," xvii. ; "Hist des CoralL, w ii., 73. 



