MADREPORARIA. 787 



Tunicate, Polyzoa, sponges, as well as a Madrepora, a Montipora and two Paracyathus. 

 The coral itself is much bored into by worm tubes and apparently Achyla. Its edges are 

 explanate, covered below by a dense wavy epitheca, the colony evidently attempting to grow 

 out at the base in competition with the various organisms there settled. 



Locality. Minikoi. The brownish-green colonies are faii-ly common on the lagoon shoals, 

 though I only brought home a single specimen, not at the time recognising its specific identity 

 from other species. 



()4. Prionastraea fusco-viridis (Q. and G.). (PI. LXIV. figs. 43, 44.) 



Quoy and Gaimard, Voy. de I'Astrol. iv. PI. XVII. fig. 8. Dana, p. 229, PI. XI. fig. 7. 

 Gard., p. 7.59, PI. XLVII. fig. 5. 



I refer twenty-nine specimens, more than half of which are of relatively large size, to 

 this species. In shape the masses vary from convex, with low elevations due to the surface 

 on which they are seated, to flat or convex with upstanding, almost perpendicularly rising 

 hillocks, sometimes flat with a corallite on the top, but more often ending in a thick ridge, 

 all with calices on the sides. 



The calices are generally polygonal in shape, about 11 nun. in diameter, but where about 

 to bud may be narrow, up to about 20 nun. long, and in the valleys very small, 8 mm. or 

 less in diameter : in depth they vary greatly, typically perhaps about 8 mm., shallower on 

 the walls and near the edges. Their walls in the valleys of the colony are generally sharp 

 pointed or ridged above, thicker below, 1 mm. or less, rising over the general surface to 

 about 2 mm., and at the edges, or on elevations, or ridges to 3—4 mm. The septa are 

 generally continuous between the calices, their exsert portions similar in every respect, not 

 rising more than '5 mm. over the walls, arched, giving the thicker an appearance of rounded 

 off ridges. They vary in the average sized calices from 35 — .55 in number, but in the more 

 elongate rise to 75 or more. No systems are distinguishable, the smaller occasionally fuse 

 with the larger, and about 18 or 20 run into a spongy columella of 2 — 2'5 mm. in 

 diameter, generally formed of very small, densely packed trabeculae from the septal edges. 

 The sides of the septa may be almost smooth or spiny. The septal teeth are always bluntlv 

 pointed and low near the walls, generally 8 — 11 in number; they may be subequal, very 

 little longer at the inner ends of the septa, or may become relatively long (2 mm.) and 

 more pointed. The innermost may rise perj^endicularly for 2 — 2'5 mm. above the columella, 

 simulating a crown of pali but more comuionly such is absent, the septal edges appearing 

 almost to merge into the columella. 



The edge of the colony, wherever visible, is covered with a thick, ti-ansversely wrinkled 

 epitheca. The walls are exceedingly dense, in section often quite solid, sometimes with a line 

 of cells in their centres. The endothecal dissepiments are thin, oblique (45° to the walls) 

 "5 — 1"5 mm. apart. Increase is by intercalicinal budding near the edges of the calices, but 

 fission not infrequently occurs, especially in the valleys. 



Locality. Very common on lagoon shoals and outer slope, often forming immense masses, 

 both at Minikoi and in the Maldives, and one piece from N. Mahlosmadulu, 24/ Colour, 

 transparent or brown to dark green over the walls, brown-green peristome, edge of stomodoeum 

 brilliant green. 



G. II. 101 



