452 Mr. G. Brook on neio Species of 



outer part of wall thin when short, but thick and keeled in 

 the stouter corallites ; length 0*5 to 2*5 rnillim., diameter 1 

 to 2 millim. Star distinct. Branches on the under surface 

 not flattened, without branchlets; corallites numerous, all 

 immersed. 



Northumberland Island {Saville-Ke^it) . 



Madrepora arcuata. 



Corallium pedicellate, flabellate or subvasiform, with nume- 

 rous slender spiciform branchlets on the upper surface ; total 

 thickness not over 2 centim. The under surface is composed 

 of a close reticulum of slender branches with elongate and 

 narrow spaces between ; corallites chiefly appressed, tubular, 

 or immersed. Branchlets on the upper surface arcuate, often 

 proliferous, 1'2 centim, long and 4 millim. thick. Apical 

 corallites cylindrical^ 1*5 millim. diameter. Lateral corallites 

 tubolabellate at an angle of 45°, 2*5 millim. long, 1 millim. 

 diameter. Star very imperfect. 



Samoa. 



Madrepora armata. 



Madrepora spicifera, Dana, Zoophytes, p. 443 (part.), pi. xxxiii. figs. 4 

 and 4 a only. 



Corallum umbellate rather than vasiform, flat above, under 

 surface obliquely pedicellate. Differs from young M. cytherea^ 

 to which Dana thought his specimen might belong, in the 

 scarcity of proliferous corallites on the spiciform branchlets 

 on the upper surface, and in the occurrence of numerous 

 very spreading and rather long tubular corallites on tlie 

 under surface. Star scarcely developed. 



Singapore; Diego Garcia; Fiji (Z>awa) ; ? Tahiti {^Chal- 

 lenger''). 



Madrepora assimilis. 



Madrepora appressa, Quelcli & ? Dana (non Ehrenberg). 



Corallum corymbose, not pedicellate ; branches horizontal, 

 coalescing into a plate, with numerous irregular corallites on 

 the under surface having a pore-like aperture ; they are 5 

 millim. long and 1*5 millim. broad, usually applied to the 

 surface throughout the whole length. Branchlets on the 

 upper surface 6 to 7 centim. long and 6 to 8 millim. thick. 

 Apical corallites 2 millim. diameter. Lateral corallites 

 crowded, ascending, subequal, beaked nariform or compressed 

 tubular with an oblique aperture ; length 4 millim., diameter 

 1"2 and 1'4 millim. to 1'8 millim. Star well developed. 



