248 A. E. Yerrill — Corals 0/ the Gemts Acropora. 



prominently and are sometimes squarrose, but in other cases form an 

 angle of about 68°-75°. The coenenchyma is loosely porous, or reti- 

 culate-porous. Immersed calicles become numerous on and between 

 the bases of the branches. 



Tahiti, U. S. Expl. Expd. No. 2032. 



The A. gemmifera (Br.) grows in much the same form as this 

 species, so far as the upper side is concerned, but it does not seem to 

 form a solid basal disk, and its short, conical, lateral branchlets do 

 not occur in this species. The corallites are quite different in form. 



Acropora Wardii Ver., sp. nov. 



Plate XXXVI. Figure 13. Plate XXXVI B. Figure 4. Plate XXXVI 



F. Figure 4. 



Coral a flat-topped, corymbose clump, arising from a large, thick, 

 short base, 150 to 250™™ broad. The larger specimens are 18 to 20 

 inches across (450 to 500™™), and 100 to 125™™ higli. The lower 

 side of the disk is composed of firmly coalesced, nearly horizontal, 

 primary branches, united into a large, thick, continuous plate, 

 except near the margin, where it becomes lobate; most of the under 

 side is covered with epitheca, to within 50 to 70™™ of the margin, 

 where the coenenchyma is at first compact, nearly even, and fineh^ 

 granulated, but nearer to the margin it bears slightly elevated cor- 

 allites, becoming more prominent close to the margin. 



The upper surface is evenly and rather closely covered with short, 

 stout, often crowded and subangular, bluntly tapered, upright 

 branches, the submarginal ones becoming oblique, and those at the 

 edge short, nearly horizontal, often coalesced. The central ones are 

 mostly 35 to 40™™ high, and 15 to 20™™ thick at base ; they are 

 mostly separated by intervals of 6 to 10™™. The cccnenchyma 

 between their bases is covered with immersed calicles. 



The axial corallites are of moderate size, often not much larger 

 than the radial ones, diameter 2.5 to 3™™, 0.5 to 1™™ exsert, with a 

 porous thickened wall, strongly costulate externally ; calicle small, 

 about 0.75™™, with 12 narrow septa. 



Radial corallites short, mostly 1.5 to 2™™, numerous, much 

 crowded, with a dimidiate or auricular lower lip, which is only a 

 little thickened and is strongly costulate externally, with small 

 pores between the costulse. The larger distal corallites are about 

 1.5 to 1.7™™ thick, often short, dimidiate-tubular, scarcely, if at all, 

 compressed, with the upper side cut away obliquely, so that the 



