44 MADREPORARIA. 
The differences between this and the closely similar branching forms from Tonga 
Islands 8 and 9, depend upon differences of growth-form and upon the shapes of the granules. 
Both are built up of radiating trabecul, the tips of which form the granules. In this coral 
these tips seem to be larger, flatter, and more nearly square. It seems, also, as if the 
horizontal tissue is a little more pronounced than in P. Tonga Islands 8 and 9. Compare 
remarks there made, p. 39 et seq. 
a. Labelled by Briiggemann “ Porites levis.” Zool. Dept. 56. 9. 24. 5. 
b. 5 me Zool. Dept. 56. 9. 24. 6. 
This is the only branching form of Porites from Fiji Islands in the National Collection. 
Two more were described by Dana, Porites “nigrescens” as certainly, and Porites “ cylindrica” 
as doubtfully, from Fiji. 
17. Porites Fiji Islands (242, (P. Fidjiensis secunda.) (PI. III. figs. 1-4; Pl. XI. fig. 3.) 
[Kandavu, coll, H.M.S. ‘Challenger’; Wakaya Reef, coll. J. S. Gardiner; British Museum. ] 
Under this heading I propose to group four specimens ; in spite of remarkable differences 
in habit, they all have the same essential structure of calicle, and apparently the same growth- 
form. 
Description.—The corallum is massive; its surface breaks up into lobules which are 
fairly uniform in size and shape, about 2 to 2°5 em. across, and showing a slight but distinct 
tendency to be bluntly ridged, rather than round-topped. The valleys between the lobules 
are shallow, except where three meet, when they dip down steeply into small hollows 
1 cm. deep. 
The calicles vary on the different specimens from 1 to 1:5 mm. The walls all show a 
sharp, thin median ridge of fused trabeculae, which rise to different heights; they are highest 
when the calicles are small and alveolate, lowest when the latter are large and shallow. On 
each side of the median ridge there is a ring of granules or flakes; in cases in which the 
calicles are small and deep and the skeleton light, these are seen to be the septal granules, but 
the whole aspect of the calicle changes when they are broad and flaky, as in the larger 
shallower ealicles ; they then form together a broad platform all round, just beneath the top 
of the median ridge. The septal formula is always complete (fig. 3, B); the four 
principal pali are very large. The ventral directive is continued into a keel, which, deep down 
in the fossa, represents a flattened central tubercle. On each side of this long directive the 
free septa bend sharply round just below the pali to form with it a trident. Still deeper down 
a clear columellar ring can be generally made out, with a varying number of attachments to 
the centre, 
