462 Mr. G. Brook on new Species of 



rarely over 7 millim. thick. Under surface with distant 

 spreading tubiform or tubo-nariform corallites, 1*5 millim. 

 diameter, with immersed ones between ; sometimes, apparently 

 owing to secondary deposition of lime, the corallites on tlie 

 under surface are obliterated. Upper surface covered with 

 suberect labellate corallites, chiefly acuminate, length 1 to 3 

 millim., diameter 1*3 millim., certain of these become tubular 

 and proliferous, and give rise to irregular groups of suberect 

 twigs about 7 millim. long. Axial and proliferous corallites 

 cylindrical, 2 millim. diameter. Star indistinct. 



Araarante Islands [H.M.S. 'Alert'), Arafura Sea {II.M.S. 

 ^Penguin '), ? Macclesfield Bank {H.M.S, 'Penguin'). 



Madrepora sarmentosa. 



Corallum flattened, bushy, extending obliquely, with short 

 blunt crowded branchlets on both upper and lower surfaces. 

 Branches 2 to 3 centim. thick, more or less fused into a solid 

 plate below. Whole upper surface studded with blunt 

 branchlets, simple or in groups of three or four, diameter 5 to 

 10 millim., length 1 to 2 centim., the more slender ones near 

 the base. On the under surface the branchlets are similar to 

 those above, but distinctly tapering, and scarcely so stout. 

 Axial corallites 3'5 to 4"5 millim. diameter, sub-hemispherical. 

 Lateral corallites on the basal parts subimmersed and dilated, 

 on the distal divisions hemicotyloid, broad nariform or sub- 

 labellate, length 2 to 3"5 millim., diameter 2 to 3 millim., 

 outer part of the wall thick and convex. The interval between 

 the branchlets is occupied by large immersed corallites. Star 

 rarely well developed. Young specimens have the wall less 

 thickened. 



Great Barrier Reef {Saville-Kent). 



Madrepora spectabilis. 



Corallum stout, corymbose; outer branches oblique and 

 proliferous, fusions rare. Central branches 6 centim. long, 

 erect, 2 centim. diameter at the base and ]-5 centim. at a 

 point only 1 centim. below the apex, usually crowded and 

 angular, greatest diameter (including corallites) occurs about 

 the middle of a branch and is often 2*5 centim. Axial 

 corallites 6 to 7 millim. diameter, hemispherical, aperture 

 only 1*5 millim. Lateral corallites variable in different 

 situations. On marginal branchlets nearly all are tubular, 

 with the inner part of the wall more or less incomplete, angle 

 45°, length 2 to 2'5 millim., diameter 1'5 millim. or a little 

 over. Wall a little thickened, margin not rounded. On the 



