AUSTRALIAN PORITES. 113 
slight columellar tubercle, which is apparently at a lower level than the four principal pali ; 
these latter are about the same thickness as the trabecule forming the wall. 
The section shows a loose trabecular structure with an absence of horizontal elements 
unparalleled in the genus. 
The colour of the unbleached coral is a dark tone of sepia. 
This coral was for long very difficult to classify : the discovery of the typical palic formula 
of Porites sets the matter at rest. For not only are the four principal pali recognisable as such 
by their positions, but diligent search showed traces of other parts of the formula, viz. the two 
directives and the columellar tubercle. 
As can be seen from the description and the figures, this is quite an extreme form of 
Porites. It, however, links on with the forms Nos. 2,3 and 4, which are also from the Capricorn 
Islands, for they all show the tendency to extreme looseness of the trabecule in the vertical 
section. 
a. Zool. Dept. 92. 12. 1. 276. 
GREAT BARRIER REEF—PALM ISLAND. 
99. Porites Great Barrier Reef (496. (P. Queenslandic sexta.) (Pl. XIV. fig. 6 ; Pl. XIX. fig. 4; 
Pl. XXII. fig. 8.) 
[Palm Island, coll. W. Saville-Kent ; British Museum. ] 
Description.—The corallum is explanate, attached by the centre or side, and with edges 
expanding freely on a wrinkled epitheca, usually drooping, and sometimes curled up. From 
the otherwise smooth surface arise mammillate processes about 1 cm. thick and from 1-2 cm. 
high, usually swollen, or even forking at the tips. 
The calicles average 1 mm. in diameter, but vary according to position. The walls on the 
level portions are either thin and raggedly trabecular as rows of separate frosted points, or 
else rather wide, with an irregular fine branching arrangement of trabecule, hardly forming 
a reticulum, the granules being finely echinulate; these give the surface a woolly appearance, 
but here and there the walls actually become irregularly reticular, and small groups of calicles 
with such walls tend to rise to form the mammille. The septa are straggling bent processes, 
about as thick as the wall trabecule, very irregular, and sometimes, especially near the edges, 
projecting from the walls as flakes. They are of very irregular lengths, and appear at different 
heights on the wall, the radial symmetry being much obscured. The pali are tall, thin rods, 
conspicuous to the naked eye as a ring. The ordinary formule (C or F, fig. 3) are most 
common, but several others appear. An inconspicuous columellar tubercle appears, often 
flattened in the directive plane. To the naked eye the calicles show the ring of pali with 
a minute central pinhole fossa inside, and a distinct furrow outside between the ring and 
the wall. 
