AUSTRALIAN PORITES. 155 
irregularly arranged as not to form any ring apparent to the naked eye, or to conform to any 
formula. A conspicuous straggling columellar tangle irregularly fills up the fossa. 
In section the coral is regularly and compactly trabecular. The colour is pale yellowish- 
brown. 
The irregularity of the internal skeleton is interesting, as is also the fact that the colour, 
not often seen in other Porites of the Indo-Pacific area, is closely like that of Nos. 1 to 5 of 
this North-West Australian group. 
a. Zool. Dept. 92. 1. 16. 1. 
150. Porites North-West Australia (g5. (2. Australie Occidentalis quinta.) 
(Pl. XXIII. fig. 6; Pl. XXXV. fig. 3.) 
[ Baudin Island, reef; British Museum. ] 
Deseription—The corallum appears to rise into an irregular flabellate process, much 
divided, and with distal branchlets on the larger divisions. The process is from 1—2 em. thick, 
5-6 em. broad, and 5-6 cm. high. The living layer may be 7-8 cm. deep. 
The calicles are superficial or slightly pitted, often sharply defined and circular, 1°25 mm. 
in diameter. The walls are flat or slightly raised, of various widths up to 1 mm., reticular, dense, 
simple, that is, composed of a median ridge and two lateral rings of synapticule, the trabecule 
rising to large, richly frosted granules, which rather obscure the wall. When the calicles are 
pitted, the median row of granules is the highest, and from it the rest slope evenly away. The 
septa are thick, regular and prominent, their edges being divided into richly frosted granules. 
The septal granules are frequently separated from the wall granules (the tips of the trabeculé 
of the inner rings of the walls) by a deep circular trough. More than one such circular trough 
may be traced round calicles where the granules are large and square. The pali form a ring 
of granules of the same character as the rest, seldom raised above the level of the septa; their 
formula is usually complete. The interseptal loculi are deep and long, and run conspicuously 
into the fossa, which is frequently deep and conspicuous. The central tubercle is small, usually 
flat and thin. 
The section is very strongly trabecular, with rounded irregular pores, and short 
inconspicuous horizontal junctions. The colour of the unbleached coral is a rather deep 
brownish-fawn. 
It is not easy to say what the exact growth-form of this coral was. There are two 
fragments, which fit together and make what might be a nearly complete stock, except for the 
loss of branchlets, or it might be merely a stag’s-horn like outgrowth of some larger colony. 
The circular troughs round the calicles are commonest in purely branching forms with 
trabecular structure. 
The colour is again closely akin to that of so many of these North-West Australian Porites. 
a. Zool. Dept. 92. 1. 16. 29. 
x 2 
