MADREPORA. 89 
81. Madrepora tizardi. (Plate XI. figs. C, D.) 
Madrepora nasuta, Bassett-Smith (non Dana), Ann. Mag. N. H. 1890, vol. vi. p. 453. 
Madrepora effusa, Bassett-Smith (non Dana), Ann. Mag. N. H. 1890, vol. vi. p. 454. 
? Madrepora plantiginea, Bassett-Smith, Ann. Mag. N. H. 1890, vol. vi. p. 453. 
? Madrepora valida, Bassett-Smith, Ann. Mag. N. H. 1890, vol. vi. p. 453. 
? Madrepora corymbosa, Bassett-Smith, Ann. Mag. N. H. 1890, vol. vi. p. 454. 
Madrepora tizardi, Brook, Ann. Mag. N. H. 1892, vol. x. p. 464. 
Corallum corymbose, a iittle concave above, 10 cm. high and 28 cm. wide. Under 
surface oblique, reticulate or almost solid, with short stunted twigs in the general plane ; 
lower surface almost naked if nearly solid, but otherwise provided with a few scattered verru- 
ciform and immersed corallites, most of which are lateral. Branches 1-2 cm. diameter at the 
base. Branchlets erect and relatively slender and elongate in some specimens, but stouter 
and more stunted in others. Apices about 1:2 em. apart. Length in the elongate form 
4 cm., diameter 6 to 8 mm. at the base; in the stunted form the length is about 3 em. and 
the diameter 1 cm. or slightly over. Axial corallites cylindrical, 2 mm. diameter or a little 
over, 1 to 2 mm. exsert; wall dense, margin sometimes slightly rounded, aperture very small. 
Radial corallites ascending and rather distant, dimidiate, gutter-shaped or hooked-nariform, 
with the outer margin curved, those below are dilated verruciform, with the aperture opening 
inwards ; these gradually become less prominent, and all are immersed at the base of the 
branchlets. The length is very variable, usually 2°7 to 4 mm., diameter about 1:6 mm., but 
all the more prominent ones are distinctly compressed. At intervals elongate, compressed, 
tubular corallites with oblique aperture occur, which indicate new outgrowths ; these are 5 to 
8 mm. long, and 1°5 to 2 mm. diameter. At a later stage when such corallites form short 
twigs with small corallites at the base, the axial corallite frequently has the terminal 6 or 
7 mm. free from buds. The prominent corallites are frequently arranged in irregular longi- 
tudinal rows, with immersed or subimmersed corallites between. The wall is a little 
thickened and very dense, surface closely echinulate. The star consists of 6 or 12 septa, all 
of which are usually narrow with the exception of the outer directive, which, in many cases, 
especially in the hooked-nariform corallites, is very broad. 
Var. beocyathus. 
Corallum broad, shallow, vasiform, the main branches becoming fused into a solid plate, 
sometimes 36 cm. long, 24 em. broad, and about 3 cm. thick, with small, scattered, sub- 
immersed corallites on the under surface. Branchlets on the upper surface short and stout, 
rarely 2 cm. long, and about 8 mm. thick. Axial corallites scarcely more prominent than the 
radial ones which surround them, and of similar diameter, but with circular or only slightly 
elliptical aperture. Radial corallites tubular, tubo-nariform, or dimidiate, with a more or less 
tapered apex, and with many subimmersed or short labellate ones between ; diameter of the 
more prominent corallites 1 to 1:6 mm., scarcely compressed, length rarely over 3 mm, 
China Sea: Tizard and Macclesfield Banks. 
