784 J. STANLEY GARDINER. 



XVIII. Genus Stephanocoenia. 



58. Stephanocoenia raaldivensis, n. sp. (PL LXII. figs. 29 and 30.) 



Colony at first incrusting, then massive, covered up to the edge with a distinct epitheca. 

 Calices, polygonal, often somewhat elongated or distorted, 4 — 6 mm. in diameter, 2 — 4 mm. deep. 

 Walls, '5 — 2 mm. thick, pointed or not, covered by the exsert ('1 — 1 mm.) rather angular or 

 slightly flattened ends of the septa, which may be continuous between the calices or alter- 

 nating. Septa, two series, 6 — 12 larger, subequal, scarcely toothed save for a crown of low, 

 rather pointed perpendicularly rising teeth against the axial fossa, and 6 — 12 very minute, 

 more or less alternating with the larger. Columella, a single fine, possibly somewhat bent 

 rod, occasionally branched once or twice, joined here and there by trabeculae to the septa. 

 In section walls solid or with a line of small vesicules in the centre ; endothecal dissepiments 

 ■5 mm. apart, thin, rather irregular, almost horizontal, occasionally joined forming vesicles; 

 columella continuous from base; septa fenestrated, especially m a line behind their thickened 

 edges, which probably represent true pali. Increase by marginal budding. 



Locality and variation. (1) The greater part of a colony 14 x 8 cm. by 6 cm. thick 

 from outer edge to the fissure zone of Minikoi reef; colour, living, olive-brown ; a heavy rounded 

 colony, walls 1 — 1-5 mm. thick, calices 4 — 4-5 mm. deep, 4'5 mm. in diameter, budding vigorous. 

 (2) Five pieces, all from Hulule, the largest an edge of an incrusting mass 12 x 9 x 3 cm. 

 from the S.-W. reef; light, often very thin walls, rather irregular on surfaces, calices smaller 

 in hollows, generally about 4 mm. in diameter, rather shallow loculi, septa often only 6 — 9 

 of the paliform series. (3) Four fragments from fissure zone of W. reef of Maradu, Addu ; 

 heavy, rather approaching (1) but calices 5 — 5-5 mm. in diameter, not more than 3 mm. deep 

 and columella tending to become compound. (4) A small colony from the passage into 

 Hulule; large, elongated (5"5 mm.) calices, top endothecal dissepiments rising to within 1 mm. 

 of edges of septa and obliterating the columella. 



XIX. Genus Acanthastraea. 



59. Acanthastraea hirsuta, Ed. and H. Ed. and H., ii. p. 502, D. 5, 4. 



Var. microstoma, Klz. (PI. LIX. fig. 6.) Klz., p. 42, V. 2. 



Var. megalostoma, Klz. Klz., p. 42, V. 1. 



In section my specimens have solid thick walls, 2 — 3 mm. thick, and dissepiments thin, 

 rather oblique, tending to be vesicular, 1"5 — 2 mm. apart. I can see no true columella, but 

 the section shows a mass of relatively large, blunt, obliquely upstanding teeth from about 

 a third of the septa, filling up the axial space. My specimens in every part so distinctly 

 belong to one or other of the two forms as to suggest that Klunzinger is here dealing with 

 true varieties and not merely fades. 



Locality. Minikoi, reef-flat (var. microstoma) and Hulule passage (var. megalostoma), 

 rare, only two specimens. 



