A. K Verrill — Corals of the Genus Acropora. 249 



aperture is wide-open, and looks upward and outward, and is visible 

 in a side view. The inner lip is often free for a short distance, but 

 usually wholly adnate. Lower down the corallites rapidly become 

 shorter and the lower lip becomes a thin crescent-shaped margin, 

 and at the base many calicles are wholly immersed. 



The septa are all narrow, except the directives; the six secondaries 

 are often present, but very narrow; in other cases abortive. Ccenen- 

 chyma openly reticulate-porous. 



East Indies or Polynesia? (coll. H. A. Ward), Yale Museum, No. 

 6151. Also in Field Columbian Museum. 



In form of coral and mode of growth, this species resembles A. 

 Guppyi (Brook), as figured by Brook, but the latter has stouter 

 branches with much larger axial corallites, and the walls of the 

 latter are not costulate. 



It has some resemblance to A. conigera (D), but the branches are 

 larger and more obtuse; the calicles are shorter, more crowded, and 

 less labiate ; the walls are more regularly costulate and fenestrate ; 

 and the ccenenchyma is finer and not so rough. 



Several specimens were in the Ward collection several years ago 

 (Nos. 6118, 61-20, (5151), from which the above description was made. 

 That collection was afterwards sold to the Field Columbian Museum. 

 A few fragments of No. 6151 are in the Museum of Yale University. 



Acropora polymorpha (Brook) Ver. 



Madrepora polymorpha Brook, Arm. and Mag. Nat. Hist., viii, p. 466, 1891. 



Catal. Mad. Brit. Mns., p. 169, 1893. 

 Madrepora abrotanoides Dana, Zooph., p. 477, pi. xli, fig. 1, 1846 (non Lam.). 



Several branches from specimens labeled as M. abrotanoides by 

 Dana are in the Yale Mus. (No. 4202). A careful study of these 

 shows that they belong to two distinct species. 



That which is most fully represented is the species figured by 

 Dana. One of our specimens appears to be the figured branch. It 

 agrees with Brooks' description of his M. polymorpha. 



It has unequal, compressed-nariform, thick-walled, prominent, 

 divergent radial corallites, with the small, elliptical, stellate calicles 

 looking obliquely upward; outer lip thick, rounded, and prominent; 

 inner lip usually free for some distance. External surface of wall is 

 densely and finely echinulo-granulate, not costulate. 



Between the larger corallites are many small tubular or verruci- 

 form corallites with a small terminal or subterminal calicle. The 

 ccenenchyma is compact and finely granulated. 



