230 A. JEJ. Yerrill — Corals of the Genus Acropora. 



Many of the proliferous branches bear rather numerous, large, tubu- 

 lar corallites, mostly with a few small basal buds, some of them thus 

 forming the axial corallites of incipient branchlets, 8 to 12"^"' long. 

 The gemmiferous corallites are much like the axial, regular tubular, 

 with the calicle terminal, and the walls rather thick and costulate. 

 Septa 12, all narrow, the directives a little wider. 



Radial corallites of various sizes intermixed. The larger ones are 

 tubular, round or slightly compressed, many of them tubo-nariform ; 

 many are dimidiate or spout-shaped; others have the aperture sub- 

 terminal and oblique. The outer lip is usually prominent, a little 

 thickened, and often slightly incurved, but in others the lip is 

 shorter and straight ; many have the inner lip short, or abortive, but 

 in others it is well developed and thin. The smaller intermixed 

 corallites have the same forms but some are short verruciform, others 

 labellate ; immersed ones are few, except at the base. 



The walls are reticnlate-porous and regularly costulate or echino- 

 costulate on the distal corallites, but often evenly and sharply granu- 

 lated on those of the lower portion of the branches. The basal coral- 

 lites are mostly short, verruciform, with the calicle terminal. Septa 

 in nearly all cases are 12, but narrow ; those of the first cycle are 

 fairly well formed ; those of the second are very narrow, sometimes 

 rudimentary; directives are rather wider than others. 



The longer tubo-nariform calicles are about 3 to 4""'" broad and 

 omm jj^ diameter ; many of these are gemmiferous at base. 



Point Pedro, Ceylon, coll. Rev. G. H. Apthorp, 1843. No. 3063. 



This species, in its form and mode of growth, resembles A. Studeri 

 (Br.), but the latter forms more regularly corymbose clumps, with 

 shorter and more conical branches, and its corallites seem to be more 

 divaricate and more labiate. A. hoeodactyla (Br.), pi. xiii, also has a 

 similar form, but the corallites are quite different. It is closely 

 allied to A. secede (type from Ceylon). 



Acropora indurata Ver., sp. nov. 



Plate XXXVI. Figure 19. Plate XXXVI C. Figure 6. 



Plate XXXVI F. Figure 13. 



Coral dense and heavy, sparingly branched, with short, stout 

 bi-anches, somewhat as in A. rohusta Dana. Branches often 25"^"^ 

 or more in diameter, subconic, or gradually tapered, obtuse. 



Axial corallites short, scarcely larger than the radial ones and not 

 much different in form ; 3-3.5™"' in diameter, 1 to 2™™ exsert ; walls 



