MADREPORA. 71 
off alternate branches at an acute angle, which may be 20 cm. long and 1°5 em. thick, 
spreading out laterally, their subdivisions subalternate and confluent, the whole habit recalling 
the espalier form of fruit-tree; a few very short branchlets arise obliquely from the anterior 
surface, but the majority conform to the general plane of growth. Axial corallites 2 to 2°5 mm. 
diameter, tubular, scarcely exsert ; wall not specially thickened, and closely resembling the 
radial ones, except in shape. Radial corallites on the anterior surface subequal, very spreading, 
boat-shaped, nariform or labellate, the aperture wide and clongate, the upper margin almost 
at right angles to the branch, the lower more or less convex, 2°5 mm. long and about 2 mm. 
thick ; wall thickened, apex often a little hooked. The corallites become a little less prominent 
towards the base of the corallum, but immersed corallites are practically absent. On the 
inferior surface the corallites are more scattered and irregularly arranged ; many open down- 
wards ; the majority are appressed, tubular, with only the outer part of the wall free. A few 
immersed corallites occur, but they are neither numerous nor generally distributed. Corallum 
moderately porous, reticulate in section; anterior surface subreticulate and echinulate; posterior 
surface dense and finely echinulate ; wall finely striate and echinulate. The star of the axial 
corallites consists of 6 rather narrow equal septa, together with a more or less incomplete 
second cycle. The radial corallites have 6 very narrow equal septa, with occasionally indi- 
cations of a second series. 
This species closely resembles M. stigmataria in habit, but differs in the almost complete 
absence of immersed corallites; the prominent corallites have a different shape and a distinct 
star of 6 narrow septa. 
Var. informis. 
A number of specimens from the Macclesfield Bank are probably referable to this species. 
The branched reticulum is, however, less flattened and more irregular, recalling the condition 
in M. nigra and some specimens of M. formosa. There are no corallites on the under surface, 
and many of those on the upper surface are round nariform, with a complete or nearly 
complete margin. 
Indian Ocean : Seychelles. 
a-c. Seychelles, 4 to 12 fath. H.M.S. ‘Alert.’ 82.10.17. 140, 147 & 148. (‘Types.) 
Var. informis. 
a-d. Macclesfield Bank, 13fath. H.M.S. ‘Penguin’ 92. 10. 17. 71 to 74. 
The following species are also provisionally included in this subgenus :— 
56. Madrepora tortuosa. 
Madrepora tortuosa, Dana, Zoophytes, p. 467, pl. xxxvii. fig. 3; M.-Edwards & Haime, Coralliaires, 
t. iii. p. 144; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 41; Rathbun, Proc. U.S. Nat. 
Mus. 1887, yol. x. p. 19; Ortmann, Zool. JB. 1888, Bd. iii. p. 150. 
Corallum cespitoso-arborescent, close-ramose ; branches crowded, often coalescing, a 
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