TRIBE III. MADREPORACEA. 455 



mulis erectis digitiformibus, crebris, subangulatis, 2|" longis et -$" 

 crassis, apice rotundata. Corallum caliculo apicali vix minims, pro- 

 minente, 1'" lato; lateralibus confertis, breviter tubiformibus aut 

 tubo-nariformibus, obsolete striatulis, apice obliquis, aperturd elliptica, 

 steM, conspicua. 



Broad cespitose, convex above, with a solid disk-form base; above, 

 branchlets erect digitiform, crowded, subangular, 2i inches long 

 and | to of an inch thick, rounded at apex. Corallum having 

 the apical calicle scarcely at all prominent, a line broad; the lateral 

 crowded, short, tubiform or tubo-nariform, obsoletely striate, oblique 

 at apex, aperture elliptical, star distinct. 



Plate 34, fig. 3, branchlet, natural size. 



Tahiti, Society Islands. Exp. Exp. 



This species has the general habit of the nasuta, but the digitiform 

 branchlets are very obtusely rounded or almost truncate at top ; they 

 are about a fourth of an inch apart, and somewhat angular. The 

 solid base in the specimen in the collections is obconical below, and 

 was attached at centre by a breadth of four inches; the whole clump 

 is a foot in diameter and six inches high. The calicles are three- 

 quarters of a line in diameter, and below are obsolescent. 



The subangular form of the branchlets, in this and other cespitose 

 species, arises apparently from the proximity of the branchlets to one 

 another. 



22. MADREPORA EFFUSA. (Dana.) 



M. late cespitosa, convexa, bast fere solida et disciformis; supra, ramulis 

 crebris, digitiformibus, 1" longis et 4-5'" crassis, ramulis margina- 

 libus vix minime liberis. Cor.allum caliculo apicali crasso, cylindrico, 

 1'" paululo latiore ; lateralibus confertissimis et in&qualibus, com- 

 presso-nariformibus, !"' longis, interdum tubo-nariformibus et pro- 

 liferis ; subtus, confertim breviter caliculatis. 



Broad cespitose, convex above, base nearly solid and disk-form; above, 

 branchlets crowded, digitiform, li inches long, and 4 to 5 lines 

 thick ; at the margin, the branchlets scarcely free. Corallum having 



