216 MADREPORARIA. 
DIEGO GARCIA. 
222. Porites Diego Garcia 31. (P. Garciana prima.) (Pl. XXXII. fig. 1.) 
[Diego Garcia, coll. G. C. Bourne ; British Museum. } 
Description.—The corallum forms massive, rounded, convex stocks, with thick, pendent, 
or encrusting edges, the latter bending outwards or under. 
The calicles are 1°25-1°5 mm. across, deep and angular. The walls thin, straight, steep 
and membranous, irregularly fenestrated, and with slightly but sharply echinulate sides, and 
jagged, not regularly denticulate, edges. The septa, faintly indicated on the membranous walls 
by the echinulz, project as very thin, short, much perforated lamelle, arranged symmetrically 
round a large deep central fossa, in which a loose reticular tangle of thin strands can be seen 
far down. The pali are inconspicuous as thin, erect rods or plates, often only faintly 
indicated in the complete formula of eight. The interseptal loculi are large and open. There 
is a thin, flattened columellar tubercle. 
Down the sides and just round the edges places may be found where the median 
membranous wall is not visible, and finely-toothed lamellate septa run continuously over the 
intervening reticular tissue to join with those of adjacent calicles. 
The section shows an open, streaming reticulum, with large oval meshes in which trabeculz 
appear sometimes as thin, delicate, glassy filaments, sometimes as lamelle. The colour is 
brownish grey. 
This coral, of which there is only one specimen, 9 em. long, 7 cm. broad and 4 em. deep, is 
very beautiful. It shows the correlation between the depth of the calicles and the development 
of the pali described in the Introduction, p. 20. 
a, Zool. Dept. 91. 4. 9. 27. 
223. Porites Diego Garcia 32. (P. Garciana secunda.) (Pl. XXXII. fig. 2.) 
[Diego Garcia, coll. G. C. Bourne; British Museum. | 
Description.—The corallum forms irregular rounded masses, clinging by close encrusta- 
tion to corroded masses of coral rock, and falling over, if the latter are loose, in which case 
the mass bends up again into the vertical. 
The calicles are 1 mm. in diameter, shallow, and round. The wall is a low, smooth, thin 
membrane, on each side of which there is usually a shelf of flat flakes, very jagged and 
irregular, and frequently with a ring of large perforations corresponding with the interseptal 
loculi. On these flakes the frosted septal granules arise, sometimes joined to the walls, and 
