184 MADREPORARIA. 
led in their upward growth by undifferentiated ceenenchyma. In P. Singapore 1 the rounded 
knobs are led by calicles usually with reticular walls or at least with reticular angles in which 
young calicles open. Then, again, the calicles are here much smaller and quite different in 
skeletal details from those of P. Singapore 1. 
The upward growth of lamellate trabecule reminds us of what has been described as the 
sheaf method of growth of Goniopora. But in this case it is not uniform, showing itself only 
in patches which give rise to the surface mounds. 
a. Zool. Dept. 91. 8. 9. 12 
185. Porites Singapore (738. (P. Singaporensis tertia.) (Pl. XXVIII. fig. 3; 
Pl. XXXV. fig. 15.) 
[Singapore, coll. Raffles Museum; British Museum. ] 
Description.—The corallum rises into a solid irregular ridge, the upper surface of which 
divides up into vertical columns, slightly nodulated and flattened, rounded and thick below, 
but thinning and widening at their tips. The columns rise some 8 ecm. high, but when 
crowded they fuse together, leaving only 3-4 cm. free. The living layer extends downwards 
from 8-9 cm. 
The calicles are 1°5 mm. in diameter, circular, sharply defined on the tips of the 
columns, but less so on the vertical sides. The walls in the former case are thin, and, like 
the septa, formed out of streaming lamellate trabeculae, seen from above as a loose open 
reticulum of nearly smooth filaments. The walls in this case rise high, and the calicles 
are deep.* Down the vertical sides, the walls are thick and consist of flakes ; on some sides 
raised into a reticulum, on others flattened down to appear as almost a solid mass. In the 
former case the calicles are deepened ; in the latter they are nearly superficial. The septa are 
radially symmetrical, very thin, and nearly smooth on the tops of the columns, but on the 
sides they show signs of granules. Distinct wall granules appear on the flakes round the 
shallow calicles ; septal granules, forming a symmetrical ring round the pali, are everywhere 
seen except in the tops of the columns. There appear to be seven pali, owing to the fact that 
the middle granule of the ventral triplet appears to lie outside the ring, though not exactly as 
far out as the ring of septal granules. There is a central tubercle, and the fine strands of the 
columellar tangle can sometimes be seen uniting the pali and tubercle. The tangle is 
conspicuous in the calicles on the tops of the columns, in which there are no pali. Owing to 
the delicacy of the septa, the interseptal loculi are large and open. 
The section shows a central lamellate streaming layer, running up the axis of the columns 
and showing at the surfaces of the tops; all round this the trabecule radiate outwards as 
filaments rather than as lamelle. The colour seems to be an ashy brown. 
There are two large specimens, a, 6, which fit together, and several small fragments, 
some of which can be fitted on to fractures of a or 6. The stock, however, was never 
quite complete, and the exact growth-form is therefore not discoverable. 
* When calicles open in a reticulum of vertical lamell they are usually flush with the surface. 
