POLYNESIAN PORITES. 35 
The calicles are conspicuous because of the deep, open fossa ; variable in size, the largest 
(1°5 mm.) being on the smooth, round-topped waves. The walls have a low, thick, median 
ridge, making a polygonal pattern over the surface, and are sometimes, especially on the waves, 
thickened by a complete or partial ring of synapticule, which make the walls look stout and 
reticular; the skeletal bars of this wall network are short and thick, and the pores enclosed 
by them round and conspicuous. The septa are also short and thick, project but a short way 
into the fossa, and seldom meet one another to form any part of the typical formula. Deep 
down in the large open fossa the columellar tangle consists of a few irregular thick strands, 
showing no striking characters. In the section, which is very dense, the walls are especially 
thick and solid, and there are immense numbers of tabule. 
Small, funnel-shaped calicles appear in the wall-angles. 
There are two fragments which fit together and show the greater part of the colony, but 
not the whole of the growth-form. In the wavy surface of this specimen and in its deep, 
stout-walled calicles, in which the septa are usually too short to meet and fuse, we have 
characters similar to those of the well-known West Indian form called Astreoides (see Part II.). 
The disappearance of the pali in this coral is certainly secondary (see, on this point, Introduc- 
tion, p. 18). 
The figure shows some of the larger calicles from one of the slopes near the top of the 
stock. The formation of the reticular wall out of a ring of synapticule is well shown in the 
figure. 
a, 6, Fragments which fit together. Zool. Dept. 1904. 10. 17. 1 and 2. 
8. Porites Tonga Islands qo)3, (P. Tongaensis tertia.) (PI. I. fig. 8.) 
[Tongatabu, coll. J. J. Lister; British Museum. ] 
Description.—The corallum closely encrusts the irregular surfaces of dead corals; about 
1 cm. thick in the middle, with thin creeping edges. , 
The calicles are conspicuous as funnel-shaped depressions, with sharp, polygonal margins 
and deep central fossze. The funnels are small and steep on the highest parts of the stock, large 
(nearly 2 mm.) and shallow on sloping sides. The walls consist of thin, straight, median ridges, 
hardly raised above the surface, broken up into smooth granules, which are small and round in 
the deep, uppermost calicles, and elsewhere lengthened out and even running together to form 
a continuous thread; these are the tips of thin, flat trabecule. On each side of and high up 
on this wall-ridge the septa appear as flakes, very small in the uppermost calicles, but large in 
the large calicles; they are joined by thin stalks to the wall-ridge. From these flakes the 
septa slope into the fossa as thin, vertical laminz, with frosted or finely echinulate sides and 
edges. In the shallower calicles (fig. 8) these thin septa become broad, flat tongues. The 
septa in the deeper calicles slope steeply down into the fossa, in the base and round the sides 
of which are a few scattered granules. In the shallower calicles the more conspicuous septa 
F 2 
