202 MADREPORARIA. 
the sides and slopes the walls thicken into a straggling, open reticulum, the threads of which 
run on into the septa. The twelve, sometimes very distinct, septa appear. at the surface 
either as slightly echinulate or granular threads, which here and there are continuous across 
the wall with septa of the adjacent calicles, or as rows of granules, in which case the whole 
surface is composed of uniform points, among which the calicles are sometimes difficult to 
trace. The central fossa is nowhere conspicuous, because it is not sharply circumscribed by 
any regular ring, and may be further obscured by a central granule. The paliform granules 
are present, but not conspicuous above those along the edges of the septa. All the granules 
are frosted, or rather bluntly echinulate. All the interspaces are large, so that the surface 
texture, especially of the top, is loose and brittle. 
The only visible section (from a broken lower edge) shows regular trabecule joined 
together by very thin junctions, leaving rounded or oval pores. The colour appears to have 
been an ash-grey. 
There is one large perfect specimen, 16 cm. long, 9 em. across, and 9 cm. high, It appears 
to have been originally attached to an Astreid. Its skeletal pattern is so far unique. Two 
minute specimens, apparently of the same kind, but since accidentally destroyed, were at one 
time seen attached to it by their epithecal saucers, under 2 mm. in diameter, and containing 
about three calicles each. These were of great interest, the texture of their skeletal elements 
being very like that of this type, but the calicles were very much smaller (0°5 mm.). This 
last fact raises a doubt as to whether they really were young colonies of this form or not. I have 
certainly noticed before that very young colonies have smaller calicles than the larger forms 
to which they seem to belong. If this is so, it helps to establish the fact of the very early 
budding to which I would attribute the structural features typical of the genus.* 
Compare the calicles with those of No, 1 (Pl. XXX. fig. 8). 
a, Zool. Dept. 88. 11, 25. 16. 
203. Porites Ceylon (99%, (P. Ceylonica septima.) (Pl. XXX. fig. 2; 
Pl. XXXV. fig. 22.) 
[Ramesvaram, coll. E, Thurston; British Museum. ] 
Description.—The corallum is globular and free, with boldly convoluted surface, the ridges 
being rounded, but with a tendency to form crests. They are about 2 cm. high, and the valleys 
are open. The stock started originally on a branch of Madrepora, but that support broke 
and left it free. The last living layer extends 9 cm., or half-way down the sides of the globe. 
‘The calicles are slightly over 1 mm., deep and conspicuous, On the tops of the uppermost 
ridges they appear in a loose, open reticulum of delicate filaments and lamin. The walls in 
these places are reticular, with clear traces of vertical membranes, the meshes and pores of 
* See Introduction, p. 24. 
