1898.] COKALS OP THE SOUTH PACIFIC. 273 



the centre (or is killed by the accumulation of sediment), but the 

 polyps remain alive at the edges, which are usually not more 

 than 12 cm. broad, so that flattened, hoUowed-out masses often 

 2 metres or more in diameter result. The edges locally, however, 

 are often killed, so that the hving corallum forms no continuous 

 line but a series of blocks, varying greatly in size, round the 

 whole mass, often attached by their whole bases, but often by 

 quite narrow stalks, so that they are frequently broken off 

 (owing to the weakening caused by the boring into them of 

 worms and other animals). The growing edge of the corallum 

 where it is visible is extremely thin (1 mm.), very closely 

 incrusting, the epitheca extending nearly to the edge. 



Calices polygonal, shallow, 1-4 mm. in diameter, or 7 in 1 cm., 

 smaller in the valleys. Cell-walls distinct, thin and linear on the 

 surface, not thickened below ; upper edges smooth, undulating, or 

 covered with low, rough spines, corresponding in position to the 

 septa in the neighbouring calices. Septa 12, rather thin, almost 

 equal-sized, projecting into the calice for about a third of its 

 breadth ; edges of secondaries and primaries sometimes fused, with 

 generally three rough spiny prominences on the upper edges, 

 the first close to the wall of the cell, the second slightly deeper, 

 about halfway along, and the third at its free edge ; the latter 

 spine sometimes fused with the middle one, larger on the primaries 

 than on the secondaries, where it is generally scarcely distinguish- 

 able and rather deep in the cell. Pali 6, fused with the edges of 

 the primary septa, but little projecting above its edge ; their 

 summits about -4 mm. below that of the cell-wall. Septal edges 

 (and paH) often joined together, but no chstinct ring of corallum. 

 Columella very variable, often scarcely noticeable, but usually a 

 distinct, thin, flattened plate with its summit little below those of 

 the pali, arising from the junction of several strands of corallum 

 from the septal edges in the centre of the calice. 



In section the corallum appears somewhat open, the longitudinal 

 elements rather coarse, while the transverse are very dehcate and 

 thin. 



Piinaf uti ; lagoon shoals and 7 fathoms. 



Var. LUTBA. (Plate XXIV. fig. 1 h.) 



Pontes conglomerata, var. lutea Quoy & Graimard, Voy. de 

 I'Astrob., Zooph. p. 249 (1833). 



Porites lutea Edwards & Haime, Cor. iii. p. 180. 



Pontes lutea Klunzinger, Die Korallthiere des roth. Meeres, 

 t. ii. p. 40. 



In this variety the wall of the cahces is usually rather rougher 

 than in the type. The septa are slightly thicker, the two outer 

 sets of spines generally smaller, the edge of the primaries fused 

 with the pali, giving 4-6 large, thick, rough and prominent 

 points round the centre of the calice, in which a small low 

 columella can with difficulty be distinguished. 



Funafuti ; lagoon shoals. Wakaya, Fiji. 

 Pkoc. Zool. Soc— 1898, No. XVIII. 18 



