TRIBE III. MADREPORACEA. 553 



in a breadth of half an inch. Some specimens are massive and sub- 

 lamellar, with obtuse lobes above, instead of proper branches. 



The species somewhat resembles the Lesueurii, in the large size of 

 its cells, but differs in their conical shape, the acute septa, and, more 

 strikingly still, in the corallum being strong instead of fragile. 



/3. elongata. (Plate 53, fig. 4.) This figure represents a specimen 

 eight inches high, consisting of three or four stout stems from a com- 

 mon base, which is 'two inches through, and sparingly branched 

 above. The upper branches are two to three inches long, an inch 

 thick at base, and half an inch at apex. The cells are very similar 

 to those of the above, yet a little smaller, about ten being counted in 

 half an inch. 



2. PORITES COMPRESSA. (Dana.} 



P. cespitosa, \\-1" animata, sublamettata, et erecta, coalita, lobata sen 

 lobato-ramosa, lobis compressis, -|" lalis (raro H"), brevibus (i"), 

 apice subtruncatis et 3-4'" crassis, non davatis. Corallum robustum ; 

 cellis\'" latis, bene potygonis,paululum profundis,plano-conicis; septis 

 acutis, tenuibus. 



Cespitose, alive for 1^ to 2 inches, sublamellate, and erect, coalescing 

 below, lobed above or lobato-ramose, lobes compressed, J to | of an 

 inch broad (rarely 1 inches), short ($ an inch), subtruncate at 

 summit, and 3 to 4 lines thick, not at all clavate. Corallum firm ; 

 cells a line broad, neatly polygonal, quite shallow, piano-conical ; 

 septa acute and very thin. 



Plate 53, fig. 5, corallum, natural size ; 5 a, cell, enlarged ; fig. 8, 

 outline of same. 



Sandwich Islands. Exp. Exp. 



The clumps are six inches or more broad, and four high, but are 

 alive only at summit for two inches or less. Below, it is very coa- 

 lescent, almost forming a solid mass, with a few large vacuities. 

 In some specimens, the broad lamellate structure is scarcely apparent. 

 The depth of the conical cells scarcely exceeds one-fourth the breadth; 

 and the septa are very thin. 



The texture is much firmer than in the West India species allied. 



139 



