INDIAN OCEAN PORITES. 209 
which, however, the tall trabecule are rounded and show no traces of being flattened into 
septa, a specialisation which is if anything still more remarkable. 
Underneath the specimen the sections of the supporting base are very puzzling. They 
appear to be sections of an Astrwopora, so many concentric shells of lamellz, about 1 mm. 
apart and supported by small radial columns,* but in this case without calicle cavities, and 
hence hardly sections of a true Astrwopora. Indeed, it seems to me that this appearance 
might be yielded by a section of the Porites colony forming the upper parts of the specimen. 
If so, the regular concentric arrangement of the horizontal elements is very remarkable. A 
section of the edge which can be seen certainly shows a tendency in the horizontal elements to 
form continuous sheets. Another argument in favour of this view is that the section which 
appears in texture so like that of Astrwopora, shows by the arrangement of the layers that the 
surface of the stock to which it belonged was once lobed or humpy, which is very rare in 
Astreopora, but is characteristic of this Porites. 
a. Zool. Dept. 1904. 10. 17. 56. 
210. Porites Ceylon 914. (P. Ceylonica quartadecima.) 
[Ramesvaram sub-fossil reef,f coll. E. Thurston ; British Museum. | 
Description —The sub-fossilised corallum was massive, with upper surface raised into two 
or three large rounded hummocks. The substance has been altered to varying depths. Some 
internal sections, however, are perfectly preserved. The intra-calicular skeleton seems 
generally to decay at the surface, while the walls persist and become smooth and solid, as if 
their elements had been partially melted together. 
From the internal skeleton we gather that the calicles were 1 mm. in diameter, the walls 
were here thin and simple, there reticular but still thin. Their height on the original surface 
is unknown. The septa seen in the transverse section are thin, straggling, and uniting in the 
typical manner, with large, open, interseptal loculi. There are no visible thickenings of the 
septa to indicate the former presence of pali. In the triplet the two laterals bend round to the 
directive; there is no portion of a ring round the fossa helping to make the typical trident 
formation of the triplet. There is a short, flattened central tubercle, and the junctions between 
it and the septal fusions are very scanty, showing that the columellar tangle was very thin and 
straggling, The trabecule are sub-lamellate, and as if streaming without any continuous 
horizontal elements. 
The hollowing out of the calicles on the decayed outer surface gives the specimen a 
very alveolar appearance, the calicles appearing deep and sharply angular. There is one large 
specimen which appears to have been nearly complete. 
a. Zool. Dept. 1904. 10. 17. 57. 
* See Notes on Astreopora, Ann. and Mag. Nat. Hist. 6° xvi. (1895) p. 273. Very close 
imitations of the extraordinary skeletal arrangement of Astreopora are frequently found in 
Madrepora. 
+ For an account of this reef by Mr. Thurston, see Bulletin Madras Government Museum, 
No. 3 (1895) pp. 91-93. 
25 
