4G2 Mr. G. Brook on new Species of 



porous, surface strongly echinulate, wall finely striato- 

 eciiinulate. 



Diego Garcia {G. C. Bourne, Esq.). 



Madrepora [Isopora) hispida. 



Madrepora securis, Quelch (non Dana), 'Challenger' Reef-Corals, 

 p. 148. 



Corallum similar to that of /. palifera^, Lamk., consisting 

 of thick plates 4 to 8 centim. broad and 2 to 3'5 centim. 

 thick, or, in other cases, of elongate, thick, rounded 

 branches 3 to 6 centim. diameter near the base and rarely 

 under 3 centim. near the apex. Apices usually flattened. 

 Corallites at the apex 2-5 to 3 millim. diameter, with smaller 

 ones scattered amongst. Walls confluent, as in 1. palifera. 

 Lateral corallites usually crowded, but sometimes rather 

 distant, short, nariform, or tubo-nariform, but the inner wall 

 always short and thin. Diameter I'o millim., length 2 

 millim. The wall and surface of the coenenchyma consist of 

 radiating spinose plates, giving a very hispid appearance. 

 Septa in two cycles, the directives broad, other primaries 

 narrow, remainder rudimentary. 



Difters from /. palifera^ Lamk., in the smaller size of the 

 corallites and the hispid character of the surface. 



Pacific Ocean ; Pliilippines ; Banda ; Ponape. 



Madrepora inermis. 



Corallum consisting of slender, laxly-divided branches, 

 which probably extend sub-horizontally. The branches are 

 about 21 centim. long and 8 millim. thick, somewhat flat- 

 tened in places, and completely or almost completely devoid 

 of corallites on the under surface, forked and divaricately 

 branched; the branchlets are sublateral, I'O to 6 centim. 

 long, 4 to 5 millim. thick, scarcely tapering ; those under 

 5 centim. in length are usually simple. In addition to the 

 more noticeable branchlets there are a few short lateral sub- 

 alternate ramiculi on the stouter branches at intervals of about 

 1 centim. ; they are 4 to 8 millim. long and 3 millim. thick. 

 Apical corallites 2 millim. diameter, 1 millim. exscrt, wall 

 scarcely thickened ; star of six septa very well developed, 

 with sometimes traces of a second cycle. Lateral corallites 

 very short, spreading, tubular, rather distant ; length 1 to 2 

 millim., diameter the same, but usually I'D millim., and the 

 base may be dilated ; those near the apex of a branchlet are 

 not so spreading, but the aperture is always rounded ; the 

 longest ones are lateral in position, and on becoming prolife- 



♦ I find that Astr<ea palifera, Lamk., is Dana's Madrepora labrota, 

 and the name has priority. 



