MADREPORA. 193 
the flattening takes place in an antero-posterior direction ; the posterior surface is nearly flat 
and the anterior more or less arched; 40 cm. long or more, 2 cm. broad, and under 1 cm. 
thick. Secondary branches lateral, subalternate, 1°5 to 12 cm. long, very much flattened 
above but more rounded near their bases. All the branches are practically devoid of corallites 
on the posterior surface; laterally they bear subalternate, flattened, tubular corallites or 
simple branches, 0°4 to 4°5 em. long and 3 to 5 mm. in longest diameter, often only 2 to 
2:5 mm. in the shortest ; those over 8 mm. long usually bear a series of small lateral corallites, 
which at first are immersed, but, with the formation of a wall around them, become half- 
goblet-shaped or nariform ; some of these in turn become tubular and give rise to new out- 
growths. The anterior surface of the corallum bears a number of scattered, subimmersed, 
and half-goblet-shaped corallites, certain of which at irregular intervals become tubular or 
subconical and project at right angles to the surface of the flabellum ; these are the only 
prominent corallites not in the general plane ; they may be 3 to 12mm. long, 2 mm. diameter 
at the apex, gradually becoming thickened towards the base. Apex of the axial corallites 
oval in section, about 2 by 8 mm., upper part of the wall rounded, with an aperture 1 mm. in 
diameter. The star consists of 12 septa; the primaries are well developed, the others only 
slightly prominent. Corallum very dense ; surface with narrow longitudinal furrows, the 
whole covered with fine echinulations. 
The habitat of the type specimen in the Paris Museum is not recorded. 
Philippine Islands. 
a, 6. Manila. R. Brown, Esq. [P.]. 93. 4. 7. 168 & 171. 
209. Madrepora tenella. (Plate XXIX. fig. E.) 
Madrepora tenella, Brook, Ann. Mag. N. H. 1892, vol. x. p. 464. 
Corallum much flattened, flabellate ; allied to Madrepora elegans, M.-Edw. & H., but more 
delicate. Stem and main branches much flattened or only slightly so; the smaller divisions 
are usually more or less rounded. Branches 7 mm. broad and rarely over 3 mm. thick, some- 
what sinuous, divisions and corallites almost all lateral: fusions frequent and irregular. 
Simple lateral corallites give rise, by increase in size and the development of buds, to twigs 
ranging from 5 mm. to 4 em. in length, the larger one provided with a secondary series of 
lateral and divaricate twigs. Axial corallites 1 to 1:5 mm. diameter, a little compressed, 
usually 3 mm. exsert. Radial corallites distant, compressed, nariform at first but soon 
becoming tubular and very spreading; diameter 1 mm.; length 1 to 5mm.; those which are 
longer usually bear distant buds. There are no immersed corallites and the whole of the 
corallum, excepting the lateral margins of the branches and twigs, is usually devoid of corallites 
of any kind. The star consists of 6 moderateiy-developed septa ; aperture a little contracted 
if circular, but usually elliptical. In some parts of a colony the more delicate twigs bear 
alternate, short, nariform to subtubular corallites on the lateral margins, which are much closer 
