196 MADREPORARIA. 
196, Porites Christmas Island (44. (P. Natalis quarta.) © 
[Rocky Point, Sea Cliff (Pleistocene), coll. C. W. Andrews; British Museum.] 
Syn. Porites aff. lutea (pars) Gregory, 1. ¢. fig. 5. 
Description.—The corallum is massive. The calicles are obscure ; the wall reticulum and 
the intra-calicular skeleton melted down into a reticulum in which it is difficult to distinguish 
the one from the other, and thus the calicles themselves are obscured, There is no radial 
symmetry to indicate their presence. The sections and worn faces show a uniform, open, 
irregular, flaky reticulum, though trabecular elements appear whenever the section is vertical. 
This specimen was placed by Professor Gregory among those he named “ P. aff. lutea.” 
It is true that all of them are massive, and the whole skeleton is melted down to a reticulum, 
but in this case the section is an undifferentiated flaky network; the polyp cavities are not 
seen running through it, indeed, they are quite undiscoverable : this differentiates it from both 
P. Christmas Islands 2 and 3. The published figure given by Professor Gregory from a 
section is not truly horizontal, but cuts through the calicles at an angle of 45°. 
The original specimen has been cut in two, and there is besides a microscopic slide. 
a, Geol. Dept. R. 3712. 
KOKOS OR KEELING ISLANDS. 
From these Islands there is but one minute fragment of a branching Porites in the 
collection, presented by Dr. H. O. Forbes. It is of interest not only because it calls attention 
to these coral Islands, which must be rich in forms of which we still know nothing, but because 
the aspect of the calicles is instructive. Thej granules which rise within the calicle are seen 
as rounded knobs, but those on the wall are flat, horizontal flakes (see Pl. XXX. fig. 1). The 
section shows the radial and concentric elements about equally stout. 
a, Zool, Dept. 84. 2. 16. 49. 
CEYLON AND GULF OF MANAAR. 
The Museum possesses a specially fine collection of Porites from the Gulf of Manaar 
which it owes to Mr. Edgar Thurston, Director of the Madras Government Museum. The 
bulk of them are from Ramesvaram, and may be divided as follows :-— 
Sixteen specimens forming a very valuable series, and all showing the same 
peculiarity of growth-form. 
