172 MADREPORARIA. 
185. Madrepora exilis. (Plate X. figs. C, D.) 
Madrepora exilis, Brook, Ann. Mag. N. H. 1892, vol. x. p. 457. 
Corallum very variable in form, shrubby arborescent to virgate with short peripheral 
branchlets, in the latter case closely resembling some specimens of M. affinis in habit ; 
others recall the habit of M. rowsseawi. In virgate specimens the branches are about 25 em. 
long and 1:3 em. thick, not including the branchlets, which vary considerably in length in 
different specimens. Branchlets usually 1 to 2 cm. long and 6 mm. thick, spreading almost 
at right angles; they are arranged all round the axis so as to give a bottle-brush appearance ; 
apices about 1 cm. apart. In one specimen the branchlets near the apex are elongate, but 
most of those below are short, unequal, and tapering. Axial corallites scarcely 2 mm. 
diameter, 1°5 mm. exsert, subcylindrical, with a well-developed star of 12 septa, the directives 
rather broader than the others. Radial corallites nariform or tubo-nariform, a little spreading, 
becoming tubular if proliferous, usually 2 mm. long and 1:5 mm. diameter, wall firm and a 
little thickened; the star consists of 6 moderately developed septa, the directives rather 
broader than the others. Between the branchlets the corallites are rarely immersed ; the 
majority have a free ring-shaped border, and a few are nariform. In bushy specimens the 
branches are shorter, more slender, and much divided, with proliferous corallites and short 
twigs scattered irregularly over the surface of the subdivisions. Five specimens from the 
same locality show a gradual transition from the virgate to the bushy form. Corallum rather 
dense; surface and wall echinulate, not striate, but the echinulations may be arranged in 
linear series. 
Pacific Ocean : Great-Barrier Reef area, China Sea, Arafura Sea. 
a-f. Port Denison. Saville-Kent Coll. 92.6.8. 102 to 106 & 
310. (Types.) 
g-i. Macclesfield Bank, 18 faths. H.M.S. ‘Penguin. 92. 10. 17. 81 to 83. 
j. Evans Bank, Arafura Sea, 10 faths. H.M.S. ‘Penguin.’ 92. 4. 5. 6. 
?k. Seychelles. H.M.S. ‘Alert.2 82. 10. 17. 170. 
186. Madrepora elseyi. (Plate XI. figs. E, F.) 
Madrepora elseyi, Brook, Ann. Mag. N. H. 1892, vol. x. p. 456. 
Corallum cespito-arborescent ; branches sometimes relatively long with a cluster of 
branchlets near the apex, at others short and much divided, resembling M. brevicollis in 
habit. Branches 1 to 1°5 cm. diameter; branchlets and proliferous corallites very numerous 
and usually acuminate. Axial corallites 2 to 3 mm. diameter, sometimes short cylindrical 
with a plane margin, more usually a little tapering. Radial corallites ascending tubular, 
rather crowded, wall thick, margin much rounded (excepting in young corallites), immer part 
of the wall shorter than the outer and often not quite so thick; length 2 to 4 mm. (average 
2°5 mm.), diameter 1°5 to 2 mm.; becoming verruciform and finally subimmersed near the 
base ; those near the apex are relatively elongate and slender ; many proliferous corallites 
