164 



parent corallum or clump. In the latter the separate cor- 

 rallites rise at various angles from the base or parent coral- 

 lum, and are short and cylindrical. A much-worn corallum 

 bears several lateral buds which arise at ri^ht angles to its side, 

 and in the case of one of them quite close to the calicular mar- 

 gin. Another specimen consists of two low corallites placed 

 at an angle of 45°, and arising from a common basal expan- 

 sion. A third interesting example is formed of a large 

 individual adherent to a shell fragment with a smaller one 

 growing from it close to its base, and at a similar angle to 

 the last. A distinctly porous coenenchyma is . visible at the 

 base of many of the specimens. 



Broad, equal costas stand out prominently on the wall 

 of the corallites, especially close to the calices, but the basal 

 expansion and also the lower part of the corallites become 

 covered with a fine but granular epitheca. The costse them- 

 selves are markedly granular; in the narrow spaces between 

 them the wall is very thin and porous. 



Exteriorly the corallites are light-coloured, but the in- 

 terior of the calices is almost invariably dark-brown or almost 

 black. On the type mass all the calices are dark-coloured, 

 and, being very deep, are somewhat difficult to read, but a 

 drawing is given of the calice of a perfect but solitary speci- 

 men which happens to be light in colour. 



The septa are in six systems with four cycles. The 

 primaries are free, the secondaries are joined by the tertiaries 

 not far from the columella, and the quaternaries again unite 

 with the tertiaries nearer the wall ; there are thus six well- 

 marked deltoid combinations in the calice. Adult specimens 

 usually have the systems complete, but in younger calices the 

 quaternaries are not fully developed. Thus the figured calice, 

 which is perhaps not quite adult, has three systems complete 

 and three incomplete ; in the latter the quarternaries are want- 

 ing in one half of each system. The primaries are stout and 

 the remaining septa diminish slightly in size according to or- 

 der. All the septa are strongly spined, and so deeply den- 

 tated as to be superficially divided into a series of longitudin- 

 al segments. At the bottom of the fossa a considerable space 

 is occupied by the columella, which consists of many papilli 

 resembling in shape the inner ends of the dentate septa. 



The bush-shaped colony figured, which is the finest speci- 

 men in the collection, has a height of 17 m.m. from base to 

 summit; it is 24 mm. long and 15 mm. broad. Its separate 

 corallites have a diameter of 7 mm. and are about 5 mm. high. 

 The calice chosen for illustration has a diameter of 5'5 mm. ; 

 its corallum is 3 mm. high. 



