MADEEPOEA. 71 



off alternate branches at an acute angle, which may be 20 cm. long and 15 cm. 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 elongate, 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 coraUites 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-(/. Macclesfield Bank, 13 fath. 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, pi. xxxvii. fig. 3 ; M.-Edwards & Haime, Coralliaires, 

 t. iii. p. 144 ; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 41 ; Eathbun, Proc. U.S. Nat. 

 Mus. 1887, vol. X. p. 19 ; Ortmann, Zool. JB. 1888, Bd. iii. p. 150. 



Corallum cespitoso-arborescent, close-ramose ; branches crowded, often coalescing, a 



l2 



