MADEEPOEA. 



51 



Proliferous clusters very variable in diameter, up to 2 cm., but not over 1-5 cm. 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 cm. long and 1'3 cm. thick. 

 Another specimen consists of an alciform lobe 27 cm. long and 20 cm. across the broadest 

 part, with m'arginal, erect, proliferous branches, up to 13 cm. long and nearly 3 cm. thick. 



Rodriguez ; China Sea. 

 a, b. Rodriguez. 



c. Macclesfield Bank, 7 to 8 fath. 

 d, e. ? 



Royal Society [P.]. 76. 5. 5. 89 & 90. 



(Types = ilf. alces, Briigg.) 

 H.M.S. ' Penguin.' 92. 10, 17. 65. 

 ? 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 5 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 difierent branchlets, but those on the same 

 branclilet 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 



