40 MADREPORARIA. 
Specimen a (see Pl. X. fig. 6, the right half) shows a previous growth apparently on its 
side ; from it the living colony has bent upwards. The calicles on the upper face of the living 
colony are flush with the surface; the walls are broad and flat, and the granulation is delicate 
and scattered; nearer the lower edge of the colony (see Pl. II. fig. 6) the granules are large 
enough to render the surface a smooth mosaic. On the under surface there’is a median ridge 
along the somewhat narrower wall. It consists of a single row of frosted granules ; this shows 
as a fine, slightly raised network over the whole lower surface. 
Specimen 6 (see Pl. X. fig. 6, on the left) is like a in general appearance, only it grew 
erect, and the calicle walls rise into a ridge, which, however, is not due to the presence of a 
single row of granules, but to a general elevation of the surface; the calicles are, conse- 
quently, slightly pitted. They are crowded on one side of the stems, but wider apart on the 
other. Correlated with this raising of the walls, we find the wall and palie granules are 
much smaller. 
Specimen c seems to be the surviving portion of a stock which had turned almost head 
downwards. Its calicles are concavely pitted over most of the upper surface of the sloping 
stems. 
Specimens d and ¢ are small colonies snapped off just above the dead tangle. 
As pointed out in the Introduction, p. 21, branching Porites, except the ccenenchymatous 
forms P. Society Islands 2 and 3, which can hardly be reckoned among the true branching forms, 
tend to develop most strongly either the trabecular or the horizontal elements; in the former 
case the surface tends to be a mosaic of granules, which are the tips of radial trabecule. The 
different forms are then difficult to distinguish, or rather the differences are difficult to 
describe in words. The student must study the photographs, which, being nearly optical 
surfaces, show very little of the lower horizontal or tangential tissue uniting the trabecule 
together. These, however, are seen clearly with a pocket lens. 
Fig. 6, as compared with fig. 5, shows the thicker trabecule of the lower part of the 
stem; while a comparison of figs. 6, 7 and 9 shows varying arrangements of the tips of radial 
trabecule. 
It is interesting to note that, side by side with this coral, in which the radial trabecule 
are the chief factors in the formation of the skeleton, there occurs another branching Porites, 
in which the horizontal elements are most developed (see fig. 8). 
There are two worn fragments of this coral in the Paris Museum (No. 190a), labelled 
as if they formed part of the original collection of Quoy and Gaimard; they were named 
“P. levis Dana” by Milne-Edwards and Haime (Ann. Sci. Nat. (1851) p. 27). We may 
gather how very little these authors were at that time prepared to recognise structural 
differences from the fact that they thought these two forms were like the famous figure 
(Pl. LIX.) of Esper’s Madrepora conglomerata, which has never yet been re-identified. Since 
Esper’s coral had “fifteen to twenty septa,” it was not a Porites at all, but a Goniopora. 
Its deep, funnel-shaped calicles, not to mention its very striking growth-form, ought to have 
distinguished it sufficiently from Dana’s levis (= P. Fiji Islands 1). 
Mention should be made of the fact that in the gradual bleaching of the corals by light, 
the organic matter within the calicles remains, causing the latter to stand out as conspicuous 
dark circles upon the light-grey background of the walls and intervening tissue. 
a. Zool. Dept. 91. 3. 6. 24. 
b-e. Zool. Dept. 1904, 10. 17. 6. 
f. A box of fragments, Zool. Dept. 1904. 10. 17. 10. 
