AUSTRALIAN PORITES. 133 
arrangement of synapticule, and tending to develop into a stout, rather stiff reticulum, some- 
times of flakes with rounded pores. But the characteristic of the coral is that the middle 
ridges of these walls are a fine, irregular, filamentous reticulum. It is the variations in the 
thickness and degree of development of this spongy ridge which give all the different appear- 
ances to the individual corals (see the figures and the descriptions of the specimens). 
The septa appear to be laminate and very porous, so that their edges are much broken. 
They have echinulate or very roughened sides, and, seen from above, often appear bent. The 
pali are small, but usually form a complete ring (formula B, fig. 3, p. 19), and rise from a 
columellar tangle which frequently shows as a ring joined by radii to a central axis, This 
rises as a tubercle, but remains below the level of the pali. 
The section shows very loose, rather thin trabecule, the horizontal elements not forming 
definite continuous tiers, as is most commonly the case. The colour of the unbleached coral 
is a light shade of sepia. 
I have grouped eight specimens under this heading because they all show essentially the 
same method of growth, and have calicles which seem to have the same principle of wall 
formation, although the variations in this respect, and consequently in the aspect of the surface, 
are very great. 
Two of them, a and 8, are mushroom-shaped ; c has the under surface of the rounded head 
just beginning to leave the stalk, or to use a simile from the mushroom, just beginning to 
rupture the velum., 
a, (Pl. XVII. fig. 3.) The top of this mushroom-shaped stock has died down and become 
a settling place for Serpulids. The calicles are conspicuous though small owing to the thickness 
of the walls, the tops of which are a rather close filamentous reticulum. 
Zool, Dept. 97. 3. 9. 223. 
b. (Pl. XVII. fig. 4.) This differs in the fact that the walls are thinner. It is possible 
to see in this merely a more rapid growth. The top of this much smaller stock was also 
killed down, and also beset with Serpulids, Zool. Dept. 97. 3. 9. 222. 
c. Is a large specimen, labelled only “The Great Barrier Reef,” but from its habit it 
clearly belongs to this series. It apparently rolled over several times, and thus now has no 
regular stalk, but grows sideways upon a free mass made up of former growths. 
Zool. Dept. 92. 12. 1. 560. 
d, Isa rounded knob on a stalk, which is mainly rotten coral. Zool. Dept. 97. 3. 9. 221. 
e. Is growing from the end of a free mass, apparently made up of overturned previous 
growths. Zool. Dept. 97. 3. 9. 225. 
f. (Pl. XVII fig. 5.) Is a free mass, with some calcareous algal concretion occupying the 
place where the stalk should be. This one has the calicles typical of a (see Pl. XVII. fig. 3), 
over one part, while those in what appears to have been its upper surface are shown in 
Pl. XVII. fig. 5. This is a striking example of the variations in aspect of calicles due to 
accidental circumstances. My experience leads me to believe that flattened walls showing a 
great deal of delicate skeletal proliferation are frequently due to the proximity of some foreign 
body disconcerting the growth and functions of the polyps. Zool. Dept. 97. 3. 9. 215. 
