156 MADREPORARIA. 
151. Porites North-West Australia 6. (P. Australie Occidentalis sexta.) 
(Pl. XXIII. fig. 7; Pl. XXXYV. fig. 4.): 
[King’s Sound, coll. W. Saville-Kent; British Museum. | 
Description.—The corallum forms mounds built up of explanate layers, the upper surfaces 
of which rise into short, conical, blunt points, with rounded tips; these may flatten and appear 
as if about to fork. Thin fresh layers creep closely over these processes, showing sharp, clear 
edges, with slightly projecting epitheca, but seldom free. The living layer may descend 
6 cm. deep down the sides of the stock. In young stocks the rising processes may be from 
1-2-5 em. high and under 1 em. thick. But in older stocks frequent incrustations may 
thicken them to 1°5 cm. and more. 
The calicles are minute, dark, ill-defined spots on a smooth surface, 0°75 mm. in diameter, 
evenly distributed, from 0°5 to 0°75 mm. apart. The walls are flat, broad, and consist of flat 
flakes, usually with only small perforations; where the perforations are large, the wall is 
a filamentous reticulum, and where minute flaky granules and ridges are scattered on their 
surfaces, such granules sometimes run radially across the walls. The septa are very obscured. 
Their bases can hardly be traced in the rough edges of the wall-flakes, but lower down small 
rods can be seen running out to the pali, whose five or six swollen knobs are sometimes 
almost in contact with the walls. The small, round, interseptal loculi descend vertically 
from the edges of the flat wall, but seldom form a complete ring. The fossa is either closed 
by a dense central tangle, or is very open, deep, and conspicuous. 
The section shows very irregular, wavy trabecule, sometimes apparently lamellate. 
This Porites has calicles which are not common. If the top edges of the walls round the 
calicles had been more regular, the calicles would have looked as if punctured into a smooth 
surface. The flat walls are remarkable, and so is the fact that in some of the smaller calicles, 
only five to six pali can be seen quite close to the walls with only faint signs of septa. 
The growth-form has already been recorded several times. There are two specimens, 
one small, showing three layers, and one much larger, the layers of which cannot now be 
counted. 
a, b. Zool. Dept. 94. 6. 16. 16 and 14. 
152. Porites North-West Australia ¢g)7. (P. Australie Occidentalis septima.) 
(Pl. XXIII. fig. 8.) 
[King’s Sound, coll. W. Saville-Kent; British Museum. | 
Description—The corallum forms nearly spherical nodules, which may be free and 
hollowed out. 
The calicles are small, 1 mm. in diameter, faintly pitted and crowded. The walls are 
irregularly reticular, delicately filamentous, with wide meshes along the tops; when the top 
edges are rubbed off, stouter threads, and even flakes appear. The septa are rather obscured, 
