46 MADREPORARIA. 
E. Prominent corallites of different sizes and shapes intermized. 
a. Corallum bushy arborescent. 
24. Madrepora valenciennesi. 
Madrepora valenciennesii, M.-Edwards & Haime, Coralliaires, t. iii. p. 1387; (? non Ortmann, Zool. JB. 
1889, Bd. iv. p. 503). 
Corallum arborescent, about 18 cm. high; branches cylindrical and subulate, several 
rising to a similar height from a common base, diverging in all directions, subdivided some- 
what as in M. nobilis. Main branches 1°8 em. diameter, gradually tapering to a large axial 
corallite. Subdivisions spreading and simple up to 8 em. in length. Axial corallites 4 to 
4-5 mm. diameter and 2°5 mm. exsert, with a very thick porous wall; septa in two cycles, 
both moderately developed. Radial corallites tubular or half-tubular, spreading nearly 
at right angles ; very variable in size, 1 to 2 mm. diameter, the larger ones with a thicker 
wall. Corallites of various lengths intermixed, those up to 4 mm. in length remain simple, 
the longer ones bear a few bud-corallites, and the axial corallite is then thickened ; there are 
no truly immersed corallites. There is only one cycle of septa in those corallites not destined 
to become proliferous ; the directive septa are very broad and nearly meet in the middle line, 
the others are narrow. Corallum very fragile and spongy-reticulate throughout ; wall fragile 
or very porous, striato-reticulate. 
The above description is based on the type in the Paris Museum. 
Indo-Pacific Ocean : Ceylon, Torres Straits. 
a-c. Thursday Island. Saville-Kent Coll. 92. 6. 8. 63 to 65. 
25. Madrepora laxa. 
Madrepora laxa, Lamarck (non Ehrenberg, non Briiggemann, &c.), Hist. Nat. Anim. sans Vert. t. ii. 
p. 280, ed. 2, p. 448; Blainville, Man. d’Actin. p. 390; Deslongchamps, Encyclop. p. 504; 
Dana, Zoophytes, p. 487; M.-Edwards & Haime, Coralliaires, t. iii. p. 146; (mon Quelch, 
‘Challenger’ Reef Corals, p. 156). 
? Madrepora pharaonis, Briiggemann (non M.-Edw. & H.), Phil. Trans. 1879, vol. elxvill. p. 574. 
Corallum arborescent, laxly branched; branches spreading, terete, slowly tapering. 
Axial corallites 2 mm. diameter, a little prominent, wall not specially thickened. Radial 
corallites small, tubular, mostly at right angles or nearly so ; crowded and unequal in length 
in front, becoming short and immersed on the reverse aspect of a branch ; diameter 1 to 
1:5 mm., length 0 to 2°5 mm. Scattered at rather considerable intervals are a few proliferous 
corallites of 6 mm. in length and 2 mm. diameter at the apex, spreading at right angles ; 
they form short branchlets at a later stage. Septa variable, usually the directives are of 
considerable breadth; the outer primaries narrow, and the second cycle still narrower. 
Corallum moderately porous in section; surface dense, finely tabulato-echinulate throughout ; 
wall not costulate. 
