178 OX THE SOLITARY CORALS, COLLECTED BY DR A. WILLEY. 



Fig. 11. Oral view of a slightly older trophozooid (x 25) with fourteen septa, of which 

 twelve — the primaries and secondaries — are conspicuously the larger. The sides of the 

 corallum are overgrown by an incrusting sponge, which extends up to the edge of the 

 calice, and gives it a smooth, regular appearance. 



Fig. 12. Commencing regrowth of an anthocaulus to form a new anthocyathus. 



(a) Profile view (x 3J), showing two rings of detachment of previous anthocyathi. 

 The top is flat owing to the recent separation of a third anthocyathus, and in its centre 

 can be seen a new anthocyathus being formed by its regrowth. 



(6) Oral view (x 5). After an old anthocyathus has become detached, a new 

 anthocyathus commences to grow out from the centre of the scar on the anthocaulus, the 

 outer part dying. Subsequently the stalk of the new anthocyathus broadens and attains 

 about the same breadth as the anthocaulus below it. Many of the septa of the bud can 

 be seen to be in the same vertical plane as those broken off, where the previous antho- 

 cyathus became detached, the septa of the bud being continuous with those left in the 

 anthocaulus. 



Fig. 13. Oral view of an anthocyathus formed by the regrowth of an anthocaulus 

 (x 6), showing the commencement of the horizontal growth. Four cycles of septa are 

 complete : of these the quaternaries fuse with the tertiaries and the latter with the secondaries, 

 while the primaries run straight to the axial fossa, which is closed in below by the 

 relatively large, papilliform columella. 



Fig. 14. Star on the aboral surface of the recently freed anthocyathus shown in 

 Fig. 18 (x 3 J). The corallum is still open between the oral and the aboral surfaces, but 

 the septa, of which four cycles can be seen in the" scar, have begun to thicken at their 

 sides. Their edges are extremely white and opaque, the corallum having evidently under- 

 gone a change which probably brought about the separation of the anthocyathus. 



Plate XX. 



(The figures on this plate, unless otherwise precisely stated, are all of the natural size.) 

 Figures 15 — 21 relate to Cycloseris hexagonalw. 



Fig. 15. An adult anthocyathus. 



(a) Oral view. The six primary septa except at the ends of the axial fossa can 

 be seen to project slightly further into the calice than the secondaries. The septa of 

 higher cycles can be seen in places very distinctly fusing with those of the cycles below 

 them. 



(b) Aboral view. The corallum has a well marked imperforate theca, beyond which 

 the septa are nearly equally exsert. In the centre is a slightly opaque area covered with 

 low spines where the anthocyathus originally separated from its stem. 



Fig. 16. Aboral view of the next oldest anthocyathus, in which the scar is still very 

 conspicuous. The costae are well .marked rows of blunt spines, extending almost to the scar. 



