Corals dredged by H.M.S. l Challenger' 



559 



directly from the periphery to the base of the columella. At about half 

 their length from the periphery to the centre of the calicle is a notch 

 followed by a sudden rise, which forms thus a distinct palus, from the 

 summit of which the line of the inferior margin of the septum slopes 

 sharply down to the base of the columella. The secondary septa are also 

 straight thin laminae ; they can be traced in the adult coral no further 

 than for about one third the distance from the periphery to the columella, 

 since they are here covered by the tertiary septa, which, bending over 

 the secondary septa at this point, bring together their upper margins, and, 

 fusing with one another, form stout laminae, which run in a radial direc- 

 tion to join the columella, and are the stoutest and most conspicuous 



Shows the arrangement of the septa in the adult and young Stephanophyllia com- 

 plicates,. The specimens were taken September 26, 1874, in 129 fathoms off the K6 

 Islands. 



A. Adult, diam. 1*7 centim. B. Young, diam. 6 millims. 



septa in the coral. From, their point of junction with the secondary 

 septa, the tertiary septa curve outwards towards the primary septa on 

 either side in each system ; and each of them being joined on its side 

 next the primary septa by a curved quaternary septum, curved lines of 

 septal matter are formed which are fused by short, transverse, synapti- 

 cular laminae to the primary septa, at points very near the centres of the 

 VOL. XXIV. 2 s 



