19 



the central scar, are salient, and are coarse and crenulate on the hase, spinate 

 or denticulate on the side- wall : the costae of the next two cycles show as striae 

 which become indistinct near the middle of the side-wall, though they are 

 distinct again near the calicular margin. 



The calicle is circular and deep. The septa are dense and smooth, and 

 have trenchant edges : they are in six systems and four cycles, with an incom- 

 plete fifth. Those of the first two cycles are pre-eminently large and exsert : 

 they descend almost to the centre of the calicle, where they end, those of the 

 first cycle in a single paliform process, and those of the second cycle in two or 

 three paliform papillae in linear series, and then they all become loosely fused to 

 form a small radiculate and papillary columella. The septa of the third cycle are 

 a good deal larger than those of the fourth : each gives off an uncate paliform 

 lamella just beyond the middle of its course, but in those half-systems in 

 which a fifth cycle is developed the tertiary septa are like the secondary septa. 

 The septa of the fourth cycle are thin crests which do not reach halfway down 

 the thecal wall, except in the half -systems in which a fifth cycle is developed, 

 where they resemble the tertiaries. 



Of the paliform processes, above described, those of the third cycle are 

 the largest and form a support for the retracted oral disk. 



The soft tissues are very thick and fleshy : the oral disk and tentacles are 

 very dark purple : the corallum is like the finest unglazed porcelain. 



Off the Goa coast, 740 fms. 



12. StepJianotrochus oldhami, Alcock. 



Btephanotrochue oldhami, Alcock, Journ. As. Soc. Bengal, Vol. LXIII. pt. 2, 1894, p. 187. 



Corallum bowl-shaped. The gently convex base has a central scar, round 

 which is a certain amount of dull epitheca : the side- wall rises vertically and 

 curves outwards again near the calicular margin. 



On the base the primary and secondary costae are very conspicuous and 

 are coarsely spinate, while those of the other cycles are hardly distinguishable 

 as granular striae; but on the side-wall all four cycles of costae are nearly 

 equally prominent and are closely granular, those of the first two cycles some- 

 times having a few teeth. 



The calicle is circular and deep, but is a good deal filled up by the septa, 

 of which there are six systems in four complete cycles with an incomplete 

 fifth. Those of the first two cycles are pre-eminently large and exsert and 

 have the surfaces granular : they all end, near the centre of the calicle, in an 

 upstanding granular paliform process of considerable size, after which they 

 unite loosely to form a small columella of three or four granular twisted leaflets. 



