AUSTRALIAN PORITES. 123 
In a section of a branching process the axial reticulum is seen to consist of stout threads 
with large open pores. The radial (trabecular) elements show no pronounced development 
over that of the concentric (horizontal). 
The unbleached coral is a faint grey-green, with traces of rose-pink at the tips of the 
processes. 
It will be seen from the description how many points this coral has in common with that 
last described, but the differences between them are so great that until we know more about 
their affinities from observation on the reef, we must describe them separately. The calicles 
show no resemblance whatever, and the growth-forms, though fundamentally the same, show 
very striking differences in detail. 
Branching forms with a flaky skeleton have already been described (see below, Table III, 
for a list of forms showing the same remarkable character). 
Gs 2 Zool. Dept. 92. 12. 1. 156. 
111. Porites Great Barrier Reef (4218. (P. Queenslandia octavadecima.) (Pl. XV. fig. 8.) 
[Rocky Island, coll. W. Saville-Kent ; British Museum. | 
Description.—The corallum forms clusters of thick, short, rather stiff, erect stems, the 
blunt tops of which divide up irregularly into new clusters. The thickness of the basal stem 
is about 2 cm.; of the branchlets, from 1-1-5 cm.; and the length of the latter, about 3 cm. 
The living layer is about 6 cm. deep. [As the layer extends much further down one side than 
it does on the other, it is probable that this specimen was one of the outermost fragments 
of a much larger stock. In large clusters the colony usually extends very much lower 
round the periphery than it does down any of the central branches. 
The calicles are superficial, about 1 mm. in diameter, and as mere marks in the smooth, 
velvety surface. The walls are broad, flat and granular, the granules being small, echinulate, 
and apparently rising from a solid layer. In bleached portions the flat, solid layer is seen, in 
parts where the granules are few and scattered, to have very fine pores in it. The septa are 
thick and symmetrical, running straight out from the edge of the solid wall. They swell at 
once into a ring of septal granules, and again into pali. The whole formula (eight) is present, 
but only the four principals are conspicuous ; the rest are short. There is a columellar tangle, 
the central tubercle appearing only deep down. 
In transverse section the radial trabecular elements are more conspicuous than the 
concentric, which are, however, stout. They are very compactly arranged, the pores being 
small and the coral consequently very dense. 
This, it will be noted, has the usual aspect and structure of so many branching Porites— 
the surface velvety and granular, and the calicles superficial. The rich brown colour of the 
dried specimen is also to be noted as that common to the majority of such forms. In this 
case the granules are very fine, and the shape of the branches is peculiar. 
a Zool, Dept. 92. 12. 1. 3. 
R 2 
