208 MADREPORARIA. 
The septa are very thin, and so perforated as to appear like filaments, which start very 
irregularly and at very different levels from the walls. The intra-calicular skeleton is thus very 
ragged and irregular; only when seen straight from above can its symmetry be made out. 
The five rod-like pali, which the septa irregularly join, reach nearly to the height of the wall. 
The columellar tangle either forms a ring round the large, deep, open fossa, or else fills it up 
with skeletal tissue. 
There are, unfortunately, no available sections; the colour appears to have been a brown, 
with a red or purple tinge. 
There are three specimens, all showing essentially the same skeletal structure, with slight 
variations. In the largest alone, a, the free edges protrude beyond the pearl shell, and the 
surface rises into mammille. The other two, 6, c, have no mammille, but show a distinct 
tendency to produce them, since groups of thick-walled calicles appear as if about to swell up. 
The wall formation is very unusual, 
Zool. Dept. 90. 6. 20. 8 (part) 
a. 
d. 
; Zool. Dept. 90. 6. 20. 9. 
209. Porites Ceylon (2913. (P. Ceylonica tertiadecima.) (Pl. XXXL. fig. 4; 
Pl. XXXYV. fig. 23.) 
[Ramesvaram sub-fossil Reef, coll. E, Thurston; British Museum. } 
Description.—The corallum rises into small nodules with lobed or knobbed surface, and 
with creeping edges often bending outwards. The lateral knobs tend to have steep sides and 
rounded tops, but this feature is not strongly marked. The creeping edge is very thin. 
The calicles are small, about 0°75 mm., rather ill defined. The wall on the uppermost parts 
of the stock, where growth is most rapid, consists of a zigzag thread joining tall, erect and 
rather stout radial flakes with smooth edges and sides. These represent both wall-trabecule 
and exsert septa, Down the sides these septa are less and less exsert till they do not rise 
above the level of the surface ; the appearance of fresh synapticular junctions tends to make the 
wall reticular, and at the same time the smoothness of the elements is lost, and frosted swellings 
or granules appear. The septal formula can be made out, but it is rather irregular, and some 
of the secondaries are very feebly developed. There are five principal pali, a very deep fossa 
without trace of central tubercle or of columellar tangle, though by focussing downwards one 
is aware of tissue running round the fossa and forming what, from above, appears to be a ring. 
The interseptal loculi are large, and their entrances into the deep fossa give the calicles a 
star-like appearance when seen from above. 
The section where growth is rapid appears closely to resemble that characteristic of 
Astreopora, The colour was a rich fawn, 
There is one small specimen of this beautiful coral. The growth is very remarkable. The 
tall septal flakes rising like scales above the level of the surface is as far as I can remember 
unique in the genus, We may compare it with P. Great Barrier Reef 5 (Pl. XIV. fig. 5), in 
