INDIAN OCEAN PORITES. 221 
The specimen appears as if the stock to which it at one time belonged had been greatly 
distorted by worm-tubes. The thick section fractured along the line of the trabecule shows 
the latter expanding like a wheatsheaf. 
The specimen had been labelled “ Porites arenacea Lamarck,” by Dr. Briiggemann. 
a. Zool. Dept. 78. 6. 6. 5. 
229. Porites Mauritius (53. (2. Mauritiensis tertia.) (Pl. XXXIL. fig. 7; Pl. XXXIV. fig. 5.) 
[Mauritius ; British Museum. | 
Description —The corallum rises from a smooth, explanate base with creeping edges into 
smooth, slender stems, which expand into clusters of four or five branchlets each. Fresh stocks 
develop with creeping edges, which overrun the dead tips of previous growths. The branchlets 
are all small, rounded or angular, about 1 cm. long, and from 1 em. to 5 mm. thick, according 
as they are swelling prior to dividing or not. 
The calicles are small, 1 mm. in diameter, deep and everywhere conspicuous, and with 
irregular outline. The walls show remarkable variations on the branchlets; they are very 
thin, ragged and incomplete. These gradually thicken to a flat-topped flaky reticulum 
(Pl. XXXIL. fig. 7) with scattered round meshes. The thin, sharp wall persists for a short 
way down the stems as a median granular ridge upon the reticulum ; low down on the stems 
the walls may be nearly 1:5 mm. across. The septa are very irregularly developed; the 
primaries, as short blunt knobs from the edge of the wall flakes, alone meet the central tangle, 
the secondaries being frequently rudimentary. Six large, round, open, interseptal loculi are 
very conspicuous. The pali are inconspicuous as short rods or knobs on the primaries. 
Where the walls are thick the calicles appear as deep, irregularly stellate punctures on the 
smooth surface. 
The section shows an open fragile network, with somewhat indistinct radial trabecule. 
There is one large bleached stock. Its peculiar feature is the irregular calicular skeleton, 
with the rudimentary secondaries. 
a. Zool. Dept. 83. 7. 27. 12. 
230. Porites Mauritius 5)4. (P. Mauriticnsis quarta.) (Pl. XXXII. fig. 8; 
Pl. XXXIV. fig. 2.) 
[Mauritius ; British Museum. | 
Deseription.—The corallum forms immense confused clusters of erect, somewhat irregular 
separate stems, each about 7 em. high, and showing from 3-4 distinct and smooth swellings, 
diminishing in size; the uppermost, which may flatten and be less than 1 cm. thick, often 
divides. The stems rise from a closely encrusting basal layer. 
