158 MADREPORARIA. 
Group III.—THE MALAYAN REGION. 
154. Porites Timor-laut 1, (P. Timor-lautaensis prima.) (Pl. XXV. figs. 1, 2; 
Pl. XXXV. fig. 6.) 
[Timor-laut,* coll. H. O. Forbes ; British Museum. | 
Description.—The corallum grows out laterally as a massive knob, to which continually 
larger masses are added, also by growing further outwards, the later ones partly encircling those 
which support it. The under surface of the mass, built up by these successive growths, is 
nearly horizontal, but the upper surface of each separate growth tends to rise into rounded 
swellings each higher than the last. The corallum appears to owe its shape to the great 
numbers of caleareous worm-tubes, which open upon its surface. The living layer is closely 
encrusting, and creeps far under the projecting mass. 
The calicles vary in size from a little over to a little under 1 mm.; very shallow, only 
faintly pitted, and crowded, sub-circular. The walls are either thin delicate zigzags of bent 
spiky filaments, or else reticular, delicate, open-meshed, and irregular. Parts of the walls of 
the same calicles may be reticular, the rest simple or zigzag. 
On the lower or under parts of the stock all the skeletal elements are thicker and more 
echinulate. 
The septa are long and echinulate, and, in the upper parts where the elements are very 
thin, there are often traces of three rings of synapticule formed of large echinule, one just next 
the simple zigzag wall, one corresponding with the septal granules, and the third corresponding 
with the pali; this innermost ring is usually complete. These rings, complete and incomplete, 
make the columellar tangle very large and irregular. There are no granules on the upper 
surface, neither wall nor septal, nor are there pali. The skeletal elements are all filamentous 
and smooth, except in patches where they become flaky, and where the filaments (which are 
often the edges of vertical lamellae) are spiky with echinulations. On the under surface 
the walls become thick and very flaky, and the calicle contains compact rings of septal 
granules and rod-like pali (mostly the five principals). A columellar tubercle fills up the 
small fossa. 
In vertical section the trabecule are close, almost as if lamellate, and separated by oval 
pores. The mass is dense. 
The growth-form is somewhat remarkable. The specimen is 15 cm. long, and appears to 
have grown as a heavy, flattened, club-shaped mass, 13 cm. wide and 7 cm. thick at the tip, from 
* Dr. Forbes kindly informs me that his corals were all found near the entrance to the channel 
named by him “ Wallace’s Channel,” and therefore in the Arafura Sea side of the islands called 
Timor-laut. 
