CORALS FROM MURRAY, COCOS-KEELING, AND FANNING ISLANDS. 185 



Other calicular characters, and the surface ornamentation of the coraUite walls and 

 of the coenenchymal surface. I believe Brook misidentified the species. 



Type: No. 281, U. S. National Museum. 



Locality. — Fiji Islands. 



Acropora (Rhabdocyathus) syringodes (Brook). 

 Plate 83, figures i, la, lb. If, id, specimen from Murray Island. 

 1893. Madrepora syringodes Brook, Cat. Genus Madrepora, p. 177, plate 33, fig. E. 



A description of a specimen from Murray Island is as follows: 



Corallum with an incnisting base, from which branches extend subhorizontally to 

 beyond 28 cm., diameter across direction of elongation 20 cm. There is considerable 

 anastomosis both near the base and among the peripheral branches and branchlets, but 

 without plate formation. Basal diameter of largest branch, 22 mm. Branches, branchlets, 

 and twigs relatively slender. Although the specimen is unfortunately badly broken, the 

 following table will give an idea of the attenuation of the branch terminals: 



Measurements of branches and tivigs of Acropora syringodes. 



Axial corallites, dimensions as given in the tables; margins not definitely rounded. 

 Walls, thickness about one-third the corallite diameter; texture reticulate, only moderately 

 dense; outer surface with distinct costules, synapticulae in the intercostular spaces. Septa, 

 first cycle well developed, meeting or nearly meeting in the axis; secondaries variable in 

 development, the cycle incomplete or complete, where complete lateral pairing may be well 

 developed. 



Radial corallites on distal part of branches and branchlets ascending tubo-nariform, 

 appressed tubo-naiiform, or appressed tubular; outer margin sometimes rounded; length, 

 3 to 3.5 mm.; diameter, about 1.5 mm.; distance between corallites at the distal ends 

 about 2 mm. Costules distinct and finely echinulate on some corallites; on others the outer 

 surface is finely echinulate without obvious costules. The walls tend toward compactness, 

 and often are solid and of vitreous appearance. Apertures elliptical. Primary septa well 

 developed, directives broad, meeting or nearly meeting each other; secondaries variable in 

 development, the cycle complete or incomplete, uniformly present in the interseptal locuh 

 next the outer directive. Some of the radial corallites resemble the axial corallites; these 

 may become proliferous and develop into branchlets. The walls of the proliferous corallites 

 only a little below the level of the aperture may be dense and subvitreous. Nearer the 

 base of the branches the coraUites are less prominent; on the upper surface they are 



