42 MADREPORARIA. 
19. Madrepora robusta. 
Madrepora robusta, Dana, Zoophytes, p. 475, pl. xxxix. fig. 3; M.-Edwards & Haime, Coralliaires, t. iii. 
p- 187; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 40; Quelch, ‘Challenger’ Reef Corals, 
p- 151; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. p. 18. 
” Heteropora cervicornis, Ehrenberg (non Lamarck), Corallenth. d. roth. Meeres, p. 110. 
Corallum very stout and laxly branched ; branches up to 4 em. thick and 30 cm. long, 
terete, only slightly tapering, excepting im some of the terminal divisions, apices blunt. 
Ultimate branches 5 to 10 cm. long, and simple or occasionally bearing a cluster of smaller 
branchlets near the apex; diameter 2 to 3 cm. near the base and 1 to 1°5 em. close to the 
apex. Axial corallites scarcely distinguishable from the radial tubular ones, rarely 3 mm. 
diameter (usually 2 to 25 mm.), and about 2 mm. exsert. Radial corallites spreading at 
right angles or nearly so, rather crowded, but of unequal length; about one third are tubular 
with circular or slightly oval aperture, a little over 2 mm. diameter and 1 to 2 mm. in length; 
wall rather thick and porous. Those between are dimidiate, nariform, or subimmersed. 
Directive septa sometimes well developed, the other primaries narrow; a second cycle is 
usually represented in rudiment. Corallum dense, surface spongy, wall strongly and evenly 
costate. 
Pacific Ocean: Fiji. 
a,b, Fiji. H.M.S. ‘ Challenger.’ 86. 12. 9. 226 & 414 
c,d. ——? Sir HE. Home, Bart. [P.]. 47.1.1.2&8. 
e-g. ——? ? 58. 2. 10.3,4& 6 
20. Madrepora grandis. (Plate I. figs. A, B.) 
Madrepora grandis, Brook, Ann. Mag. N. H. 1892, vol. x. p. 457. 
Corallum stout, arborescent, laxly divided. One specimen, which consists of the distal 
part of a colony, is 36 em. long, and the main branch is 3 cm. in diameter. Branches simple 
or forked, some which are 17 em. long and 2 em. thick are simple, slowly tapering, attenuate. 
Near the apex of a colony the divisions are, however, sometimes much shorter and more 
numerous. Axial corallites 3 mm. diameter, cylindrical, considerably exsert (2 to 3 mm.) ; 
wall very porous; star moderate or well-developed. On the distal 5 em. of a branch 
the radial corallites are ascending tubular, with thin wall and deep large cup, practically 
without septa; length 4 to 5°5 mm., usually cylindrical, but sometimes a little compressed, 
2 mm. diameter, inner part of the wall as prominent as the outer. Such prominent corallites 
are about 5 mm. apart, with smaller tubular, nariform, or subimmersed between, diameter 
about 2 mm.; wall usually thin, but a little thicker in the more elongate corallites. Below 
the distal 5 em. (approximately) of a branch, all the radial corallites extend at right angles 
to the axis and none are over 2 mm. long; they are tubular in form and become gradually 
shorter towards the base. The condition differs from that of MW. robusta in similar situations 
in the thinner wall, in the absence of a recognizable star of septa, and also in the absence 
