MADREPORA. 51 
Proliferous clusters very variable in diameter, up to 2 cm., but not over 1°5 em. long. Axial 
corallites cylindrical, 2 mm. diameter and up to 3 mm. exsert, usually with thick wall. 
Radial corallites dimidiate or labellate ; wall thin but firm, usually thicker in the outer part 
of those destined to form axial corallites ; very unequal in length, the more prominent ones 
about 1°3 mm. diameter. Star not well developed, often only the directive septa recognizable. 
Corallum moderately porous ; surface reticulate ; wall striate, echinulate near the base. 
One of the Rodriguez specimens referred to M. alces, Dana, by Briiggemann indicates the 
formation of plates by the fusion of short proliferous branches 5 em. long and 1°3 em. thick. 
Another specimen consists of an alciform lobe 27 em. long and 20 em. across the broadest 
part, with marginal, erect, proliferous branches, up to 13 em. long and nearly 3 cm. thick. 
Rodriguez ; China Sea. 
a, 6. Rodriguez. Royal Society [P.]. 76.5. 5. 89 & 90. 
(Types=M. alces, Brigg.) 
c. Macclesfield Bank, 7 to 8 fath. H.M.S. ‘Penguin.”? 92.10. 17.65. 
d, e. 2 —? 93. 4. 7. 72 & 73. 
F. Numerous tubular corallites develop a rosette of bud-corallites around the base, most of 
which do not lead to the formation of branches. 
31. Madrepora decipiens. (Plate XIV. figs. B to D.) 
Madrepora decipiens, Brook, Ann. Mag. N. H. 1892, vol. x. p. 456. 
Corallum consisting of stout subprostrate branches with erect digitiform branchlets, or 
more slender and irregularly fastigiate. Radial corallites of two types—the one stout and 
often bearing buds, the other thin-walled, labellate or subimmersed. 
Form a.—Branches subprostrate, 2°5 to 3°5 cm. diameter, provided with erect, tapering, 
digitiform branchlets often about 3°5 cm. apart at the apex; often simple, 6 cm. long and 
2 cm. diameter; in other cases the branchlets are more slender and divided near the apex. 
Axial corallites cylindrical, 2°5 to 3 mm. diameter, not over 2 mm. exsert; the star consists of 
12 equal and very narrow septa, or of an equal and moderately-developed primary series and 
a narrower second cycle; in either case the directive septa are not more prominent than the 
others of the same cycle. Radial corallites crowded, of two kinds—the one stout and 
prominent, the other labellate, subimmersed or immersed. The prominent corallites are 
cylindrical, with a more or less deep notch in the inner part of the wall; near the apex of a 
branch they are usually more or less ascending, but all are at right angles on the stouter 
parts; diameter 2 to 2°2 mm., length 2°5 to 6 mm.; the corallites are longest near the apex 
of a branch and the inner part of the wall is here scarcely shorter than the outer in many 
cases, but the aperture is often somewhat elliptical owing to the wall being thinner on the 
inner side; the length varies considerably in different branchlets, but those on the same 
branchlet are usually subequal; wall firm, margin not rounded, aperture fully 1 mm.; the 
longer ones often bear one or two buds. Between the prominent cylindrical corallites numerous 
