MADREPORA. 85 
to 2 mm.; the stouter ones bear buds. The wall is moderately thick excepting in its inner 
part, which is thin and often not quite so prominent, giving an elliptical aperture. Usually 
at a point 1 to 1°5 cm. below the apex of a branch the corallites become shorter and verruci- 
form, but scarcely any are completely immersed, even at the base of the branches. Star 
distinct, but not very broad ; it consists of 12 septa, with the outer directive usually broader 
and stouter than the others. Corallum dense; surface and wall closely and finely echinulate ; 
margin distinctly rounded in all except the youngest corallites. 
Indian Ocean: Diego Garcia. 
a b,?c. Diego Garcia. G. C. Bourne, Hsq. [P.]. 91.4.9.5,9&10. (Types.) 
B. Corallum corymbose, more rarely cespitose : corallites elongate, with dense wall 
and often acuminate apex. 
76. Madrepora appressa. 
Heteropora appressa, Ehrenberg, Corallenth. d. roth. Meeres, p. 109. 
Madrepora appressa, Studer, Mitth. naturf. Ges. Bern, 1880, p. 22 (non Dana, M.-Edwards & 
Haime, &c.). 
Corallum corymbose (?), the under surface of the branches horizontal and fused into 
flattened plates, with a few thick conical corallites below, most of which are lateral, and a few 
immersed ones scattered over the general surface. Branchlets on the upper surface about 
4 to 6 cm. long and 1 to 15 em. thick at the base. Axial corallites 2 to 2°5 mm. diameter, 
with rounded margin and small aperture. Radial corallites elongate and appressed with 
rather thick curved wall, up to 8 mm. in length and 2 mm. thick, the more elongate ones 
have a slit-like aperture and are proliferous : all are very irregularly placed. ‘The usual form 
is hooked labellate, with a thick blunt and frequently incurved apex; those below are short 
or immersed; aperture 1 mm.; 6 primary septa, prominent. Corallum moderately porous, 
but firm; surface dense and echinulate, or tabulato-echinulate with elongate pits between ; 
wall dense and echinulate, not striate. 
This species differs from the form which I believed to represent Dana’s M. appressa in 
its more robust habit, and particularly in the longer and stouter radial corallites with an 
elongate, thick and blunt apex. It may, however, be only an individual variation, and I have 
not seen elsewhere any specimen which agrees with it completely. 
Habitat of the type specimen (Berlin Museum) not recorded. 
?a. Evans Bank, 15 fath., Arafura Sea. H.M.S. ‘Penguin.’ 92. 4. 5. 3. 
77. Madrepora assimilis. (Plate XX. fig. A.) 
Madrepora appressa, Dana (non Ehrenberg), Zoophytes, p. 457, pl. xxxiv. fig. 5, pl. xxxi. fig. 8; 
? Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 42; ? Studer, Mitth. naturf. Ges. Bern, 1880, 
p- 22; Quelch, ‘ Challenger’ Reef Corals, p. 163; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. 
p- 12. 
N 
