MADREPORA. \ 155 
annular and immersed towards the base of the branch. The septa are very narrow, even in 
the axial corallites; in the radial ones usually only the directives are recognizable. Corallum 
dense ; surface and wall closely echinulate. \ 
+ 
Var. mammillata. (Plate XXIII. fig. A.) 
Two of the Rodriguez specimens consist of incrusting colonies in which cha Were are 
indicated only by conical protuberances, with very numerous and small immerstd corallites 
between. The protuberances are about 7 to 10 mm. high and’6 to 11 mm. digmeter, the 
axial corallites 3°5 mm. diameter ; the radial ones crowded, scarcely prominent, withthe walls 
confluent. The larger specimen is 15 em. long and 8 cm. broad. Ne 
Rodriguez. 
‘\ 
a. Rodriguez. Royal Society [P.]. 76.5.5,.103. (Type=M. plantaginea, Brigg.) 
Var. mammillata. 
b,c. Rodriguez. Royal Society [P.]. 76.5. 5.86 & 87. (=WM. plantaginea, Briigg,) 
\ 
\ 
E. Wall of the radial corallites rather thin and firm or slightly thickened, but not rounded \ 
at the margin. 
164. Madrepora australis. (Plate XXIII. fig. C.) 
Madrepora australis, Brook, Ann. Mag. N. H. 1892, vol. x. p. 453. 
Corallum small cespitose, about 8 cm. high from a base 9 cm. in diameter. Branches 
usually divided near the base into 2 or 3 erect digitiform branchlets, all of which reach to 
about the same level, length 3°5 to 4:5 cm., diameter 2 to 25 cm. at the base, the distal 
divisions 1:3 to 2 em., angular below, slowly tapering to a blunt apex; apices about 2:3 cm. 
apart. Axial corallites 3 to 4mm, diameter, hemispherical or a little tapering in the smaller 
ones. Radial corallites rather distant and unequal, short, spreading, tubular, with more or 
less oblique apex and plane margin; aperture not compressed, diameter 1 to 25 mm., the 
more prominent ones usually about 2 mm. diameter; length 1 to 2 mm., excepting near the 
base of the branches, where a few are dilated and others more elongate and less spreading ; 
the wall is a little thickened but not dilated, and the inner part is rarely entirely wanting. 
A few subimmersed and immersed corallites are scattered between the more prominent 
ones. Corallum moderately porous; surface spongy and echinulate; wall finely striate and 
echinulate. 
A specimen, the habitat of which is not recorded, is referable to this species, but 
differs in two or three points. The branches are more acuminate (axial corallites 3 mm. 
diameter), and the radial corallites in many cases are gutter-shaped, owing to the imperfect 
development of the inner part of the wall, and sometimes the lip is quite thin. It agrees, 
however, with the type specimens in the mode of branching and in the spreading unequal 
corallites, which are not compressed. The species is distinguished from M. guppyi by the 
