MADREPORA. 171 
broad. Stems 2 em. thick; branches and branchlets ascending, 2 to 10 em. long and 8 to 12 
mm. thick, proliferous and scarcely tapering except near the apex. Axial corallites 3 to 4 mm. 
broad, 2 mm. exsert, margin a little rounded, aperture 1 mm. Radial corallites 1:5 to 2 mm. 
broad, 3 to 4 mm. long, usually thin-walled, aperture round or oval, 1 to 15 mm. diameter ; 
they are unequal, rather appressed half-tubular, with small subimmersed ones between ; 
others are completely tubular and bear buds ; below they are more appressed, or verruciform, 
and finally immersed. Corallum moderately but not openly porous in section ; surface spongy- 
reticulate and echinulate ; wall striate. 
Several specimens are in the collection from the Persian Gulf which resemble M. variabilis 
in habit, but have the thinner-walled tubo-nariform corallites of this species. One specimen 
forms a corymbose clump 38 cm. in diameter. 
Indian Ocean: Red Sea, Persian Gulf. 
a-d. Persian Gulf. A.S. G. Jayakar, Esq. [P.]. 91. 1. 18. 5, 8, 22 & 31. 
? —— ? 93.4. 7. 114. 
é. 
184. Madrepora rousseaui. 
Madrepora rousseauti, M.-Edwards & Haime, Coralliaires, t. iii. p. 138. 
Corallum small, shrubby arborescent, consisting of tufts of slightly tapering branches 
up to ll em. in length; they are 1 cm. diameter from the base to within 3 em. of the apex, 
then tapering gradually to the axial corallite. Hach branch bears numerous proliferations, 
5 to 30 mm. long, which are prolonged and thickened tubular corallites bearing radial 
corallites in proportion to their length. Axial corallites 2°5 mm. diameter (M.-Edwards 
gives 3 mm.), 2 mm. exsert, with thick cylindrical wall. Radial corallites tubular or half- 
tubular at an angle of about 45°, chiefly 2 mm. diameter and 2:5 mm. long, but many are 
longer ; inner margin often incomplete, wall moderately thick, a little rounded at the margin ; 
those over 2°5 mm. long bear one or two small buds near the base, and thus lead on to more 
marked proliferations and branchlets. A few immersed corallites are scattered between the 
others, excepting near the apex of a branch and on the younger branchlets. Septa of the 
axial corallites in one cycle only, subequal, moderately developed; those of the radial 
corallites also in one cycle, directives broad. Corallum dense; surface a little pitted and 
finely echinulate; wall finely echinulate, excepting in the younger corallites, where it is 
striato-reticulate or fenestrated. 
The above description is based on the types in the Paris Museum. A specimen in the 
collection of the British Museum, which appears referable to this species, has the axial 
corallites 2 mm. in diameter, the branches gradually tapering through their whole length, and 
the shorter corallites nariform rather than tubular. 
Indian Ocean: Seychelles, Malacca. 
a. Malacca. Sir E. Belcher [P.]. 42. 11. 30. 18. 
