TRIBE III. MADREPORACEA. 557 



extremities are scarcely more than a third of an inch in breadth, and 

 about two lines thick. 



Forties divaricata, Lesueur, Mem. du Mus., vi. 288. 



NOTE. Esper figures, on plate 59, what appears to be another species, with excavate 

 cells, differing from either of the preceding. This character of the cells is particularly 

 mentioned in the description. It has in other respects the habit of the cylitidrica, grow- 

 ing in a clump of slightly divergent crowded stems ; the branches are, however, less 

 regular, though nearly of the same size. His specimen was from Madagascar. It may 

 be designated the P. conferta. Madrepora conglomerata, Esper, Fortsetz. i. 71, tab. 59. 



II. Cellis viz excavatis, aut omnino super ficialibus. 



8. PORITES NIGRESCENS. (Dana.) 



P. ramosa, cespitosa, 6-8" animata ; ramis elongatis, crebriusculis, 

 sensim attenuatis, interdum coalitis, flexuosis, subteretibus, obtusis, 

 caulibus basi interdum 1-li" crassis, ramulis J-J" crassis et 2-2J" 

 longis. Corallum subrobustum ; cellis majusculis, vix excavatis aut 

 superfaialibus ; septis latis granulosis. 



Ramose, cespitose, alive for 6 or 8 inches ; branches elongate, rather 

 crowded, sometimes coalescing, flexuous, subterete, gradually taper- 

 ing, obtuse; stems occasionally 1 to 1^ inches thick at base, branch- 

 lets to J an inch thick and 2 to 2 inches long. Corallum firm; 

 cells rather large, scarcely excavate or superficial ; septa broad and 

 granulous. 



Plate 54, fig. 1, corallum, natural size; 1 a, surface with the cells 

 enlarged ; 1 b, transverse section, enlarged. 



Feejee Islands. Exp. Exp. 



The clumps are eight inches or more high, and much branched, 

 and become black or nearly so on the death of the polyps. The sub- 

 terete branches are long and somewhat tapering, a little flexuous and 

 distantly coalescent. Above, the cells are a little excavate, but below, 

 they are superficial ; they are usually black, with the septa dark 

 brown, and there are about eight to a half inch. Under the micro- 

 scope the surface appears granulous. 



One specimen differs from the others in being a simple stem diva- 



140 



