560 Mr. H. N. Moseley on the true 



lengths of each of these. Thus is brought about the peculiar arrange- 

 ment which forms the most striking feature presented by the adult coral, 

 and which consists in the presence around the elongate columella of six 

 symmetrically arranged oval holloiu spaces, each of which is enclosed 

 by a loop-like lamina, as it were, of hard tissue, and bisected longitu- 

 dinally by the inner end of the pcdus of the corresponding primary septum 

 (see accompanying diagram, p. 559). 



In their further course, the tertiary septa are bent from side to side in a 

 most remarkable manner, and fusing at successive distances outwards with 

 the shorter quaternary and still shorter quinary septa, which are likewise 

 extremely undulate in their course, a series of chambers is formed, which 

 chambers are closed at their peripheral ends by processes of synapticular 

 matter. The chambers are arranged symmetrically in each system on 

 either side of the secondary septum, and successively decrease in size 

 and increase in number from the centre outwards. The chambers 

 opening all over the coral give it a most remarkable honeycombed ap- 

 pearance. 



The columella is an elongate, thin, vertical lamina stretched in line 

 with an opposite pair of primary septa. At its base it is provided with 

 rootlets, which join the primary and fused tertiary septa. 



In a young specimen of this coral, without reference to which the true 

 nature of the complicated structures in the adult could hardly have been 

 determined, the corallum is almost symmetrically biconvex and perfectly 

 circular ; but the columella is elongate, as in the adult. The columella 

 is papillar rather than laminar, and represents the rooted base of the- 

 adult columella. There are sixty perfect costse present at the margin 

 of the calicle, and the commencement of two more in each system {i.e. 

 twelve in all). There are twelve concentric rows of perforations in the 

 base. The septa are not nearly so much contorted as in the adult, and the 

 synapticular junctions between them not being as yet formed, the division 

 of the septal cavities into successive chambers is not apparent as in the 

 adult. No superficial fusion of the primary with the curved extensions 

 of the tertiary and quaternary septa has as yet taken place ; hence no 

 six-rayed star or flower appears in the centre. Stout transverse 

 granular projections are present on the upper margins of the septa, the 

 sources of future synapticular connexions. Only four cycles are com- 

 plete in each system. Two members of the fifth cycle are present in 

 each system, and are those nearest the primary septa on each side. An 

 additional pair of quinary septa is just commencing to grow in each 

 system, and branching off from the peripheral ends of the quaternary 

 septa which are next "the secondary, but on that side .of them which is 

 nearest the primary, i. e. opposite to the secondary. A very short 

 branch of the costa belonging to the interspace between the quaternary 

 and secondary septa passes into each interspace formed between these 

 newly grown quinary septa and the quaternary adjoining. 



