154 MADREPORARIA. 
The calicles are minute, 0°75 mm. in diameter, without definite outline to the naked eye, 
superficial. The wall is a reticulum of a simple kind, viz. a median ring thickened by a 
single synapticular ring on each side, yet together forming a single wall* as a reticulum 
of thick strands, which end at the surface as stout granules with finely echinulate surfaces. 
The meshes of the wall reticulum are large, and somewhat regularly arranged. The septa are 
thick, and their sides are very finely and closely echinulate ; the divisions of their upper edges 
into septal granules and pali is not very marked, and the pali are not conspicuous as a raised 
ring. They are seen rather as enlargements of the septal tips, and appear to be in the complete 
formula H (fig. 3). The fossa is deep, but nearly filled up by a large very finely echinulate 
central column rising free nearly to the surface, and with no apparent junctions with the 
septa or pali, The interseptal loculi are large, deep and open, in spite of the thickness of the 
septa. 
The section appears to be densely trabecular, the trabeculee being nodulated. The colour 
of the unbleached coral is again a light yellowish-brown. 
There is only one specimen. The calicles appear to be unique in the exquisitely delicate 
echinulations hardly visible on the top of the stock (Pl. XXIII. fig. 3), pronounced at the 
sides (Pl. XXIII. fig. 4). 
a. Zool. Dept. 92. 1. 16. 13. 
149. Porites North-West Australia (4. (P. Australie Occidentalis quarta.) 
(Pl. XXIII. fig. 5; Pl. XXXYV. fig. 1.) 
[Baudin Island; British Museum. | 
Description.—The corallum rises on a rather narrow neck into a rounded oval mass, some- 
what flat-topped, and irregularly divided into transverse swellings. The living layer has a 
depth of 4-5 em.; it bends only slightly under the overhanging bulging of the sides of the 
stock, and seldom with growing edges. The coral mostly dies progressively upwards and 
is covered over with an epithecal film. 
The calicles are minute, yet conspicuous, variable in size, about 0°75 mm. in diameter, 
angular, and distinctly depressed. The walls are simple membranes, hardly fenestrated, hence 
with continuous edges, which are either straight and thread-like or zigzag, sometimes both, on 
the different sides of one and the same calicle ; short ragged processes project irregularly from 
the top edge of the wall as the beginnings of the septa. Lower down the crooked roughened 
septa swell close to the wall, and the swellings at times unite so as to show traces of an inner 
synapticular wall. Within this the septa are very irregular and thin, and their radial symmetry 
is frequently obscured. They rise slightly at the centre into low, often flattened, pali, so 
* That is, not a thin median ridge with a distinct synapticular ring running round as if part of 
the intra-calicular skeleton, ef. the “ trimurate ” condition described in Introduction, p. 16, 
