96 PERCY SLADEN TRUST EXPEDITION 



1904. 1 Goniastrce.a favus, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 773 (non Goniastrcea /aims, 



Klunzinger). 

 1904. Stephanoccenia maldivensis, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 784. 

 1904. Prionastrma pentagona, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 785. 

 ? 1907. Favia hawaiiensis, Vaughan, Recent Madreporaria of the Hawaiian Islands and Laysau, U.S. Nat. 



Mus., Bull. 59, p. 105, pi. 26, figs. 3 and 3a. 



Corallum. Incrusting or massive, often with low humps. Corallites polygonal. 

 Walls fused, the inter-calicinal partitions thus formed up to 3 "6 mm. thick, usually about 

 •75 or 1 mm., ridged, solid in section. Calices up to 6 mm. in diameter, average 4 — 5 mm., 

 depth 3 — 4 mm. 



Septa usually thin, sometimes thickened, vertical, with denticulate or entire edges, 

 smooth or slightly rough sides, 20 — 30 in number, average 22 — 24, alternating in adjacent 

 corallites or meeting at angles over the walls. 9 — 14 septa meeting columella, very 

 slightly exsert, each with a bluntly pointed conspicuous paliform lobe. Columella spongy, 

 5 — ^ width of calyx. 



Multiplication by unequal fission ; when definite walls are formed round the daughter 

 corallites, they appear like buds intercalated among the larger corallites. 



Towards edges inter-calicinal walls become thicker (calices then decreasing in width 

 from margins to bases), some of the subsidiary septa so narrow as to be hardly recognisable, 

 columella rudimentary or even absent. 



Polyps. (1) Both entocoelic and exocoelic tentacles present. (2) Stomodseal ridges 

 broader than thick (some of them twice as broad as thick), constricted at their bases, and 

 with convex inner surfaces. In contrast to the small size of the polyps their ridges 

 broader than in all the previous species. (3) Seven to nine principal couples of mesen- 

 teries. (4) In the stomodseal region of polyps subsidiary couples of mesenteries about 

 twice the number of principal couples. (5) In the stomodseal region of polyp, entocoelic 

 pleats narrow and thick — except towards middle of mesentery where they are much 

 broader, thinner and occasionally sub-divided — and not extending beyond outer two-thirds 

 of width of principal mesenteries ; mesenterial mesoglsea thickened only in region of 

 broader pleats, and near stomodseal attachment, elsewhere quite thin. (6) Mesenterial 

 endoderm extremely thin, except on either side of the broader pleats and near the 

 stomodseum. (7) Convolutions of mesenteries never abundant, absent towards base 

 of polyp. 



Remarks. A. Polyps. These are small, circular or polygonal in outline, with little 

 or no coenosarc. In one polyp there are 9 principal couples of mesenteries, of which 

 4 are incomplete ; in 2 others 7 couples, of which 2 are incomplete. Subsidiary couples 

 number about 20, of which 5 or 6 reach up to half or two-thirds the width of the 

 principal mesenteries, the remaining couples narrow and hardly extending below the 

 stomoda3um. Every tentacle has a swollen terminal battery similar in structure to those 

 of F. favus, its nematocysts I having each a spiral of about 33 turns. The stomodseum 

 is oval in outline, its longer diameter measuring about 1'25 mm. Nuclei are not thickly 

 crowded in its ridges as is the case in F. favus ; occasionally nematocysts I and III are 

 present. The mesoglsea is thickened in each ridge, the fibres passing from the former into 

 the latter, lying close together in the middle of the central non-nucleated granular region. 



