MADREPORA. 69 
sometimes over 8 cm. long and about 8 mm. broad. Under surface of the branches provided 
with distant, spreading, tubular or tubo-nariform corallites about 1-5 mm. diameter, with 
scattered immersed ones between; sometimes the immersed corallites are absent, and in one 
specimen the tubular corallites are proliferous and form twigs about 6 mm. long. The upper 
surface of the reticulum is covered with suberect labellate corallites, chiefly with a pointed 
apex ; they are 1:3 mm. diameter and 1 to 3 mm. long; wall thin, but firm. Certain of these 
corallites become tubular and proliferous, and give rise to irregularly grouped suberect twigs, 
usually about 7 mm. long. Axial and proliferous corallites cylindrical, 2 mm. diameter and 
2 to 4 mm. exsert, wall a little thickened. Star imperfectly developed, usually only the 
directive septa are recognizable. Corallum moderately dense ; surface striate and echinulate ; 
wall striate, echinulate near the base. 
Var. cuspidata. 
A variety from the Macclesfield Bank differs from the type in having normal twigs on the 
upper surface 1 to 1:3 cm. long and 3 to 4 mm. thick, distinctly tapering, simple or more 
usually bi- or trifid; corallites nearly all immersed ; prominent corallites open, with a narrow 
labellate lip, star not recognizable. 
Pacific Ocean: Amirante Islands, Seychelles, Arafura Sea, Macclesfield Bank. 
a-d. Eagle Island, 10 fathoms, Amirante Islands. H.M:S. ‘Alert’? 82. 10. 17. 131, 
135,155 & 93.4.7.141. (Types.) 
e. African Island, 10 fathoms, Amirante Islands. H.M.S. ‘Alert. 82. 10. 17. 187 
(part.). 
f. Eagle Island, 10 fathoms, Amirante Islands. H.M.S.‘ Alert” 82. 10. 17. 141. 
(Proliferous var.) 
g. Amirante Islands. H.M.S. ‘ Alert.” 82. 10. 17. 115. 
h. Seychelles. H.M.S. ‘ Alert.? 82. 10. 17. 145. 
i-m. Macclesfield Bank, 13 fathoms. H.M.S. ‘Penguin’ 92. 10. 17. 
1 to 5. 
?n. Evans Bank, 15 fathoms, Arafura Sea. H.M.S. ‘Penguin. 92. 4. 5. 4. 
Var. cuspidata. 
a-f. Macclesfield Bank. H.M.S. ‘Penguin. 92. 10. 17. 6 to 
10 & 18. 
?g,h. Macclesfield Bank, 13 fathoms. H.M.S. ‘Penguin.’ 92. 10. 17. 
11 & 12. 
53. Madrepora oligocyathus. (Plate VII.) 
Madrepora oligocyathus, Brook, Ann. Mag. N. H. 1892, vol. x. p. 460. 
Corallum forming a fan-shaped and pedicellate half-vase ; length 60 cm., breadth 53 em., 
diameter of pedicel 7 em. ‘The general form of the corallum closely resembles that of 
M. microclados; branches forming an open reticulum, the meshes of which are not usually 
elongate; diameter of branches 8 to 15 mm.; branchlets on the under surface about 1°5 em. 
long and 5 mm. diameter at the base, somewhat tapering, nearly all are a little appressed, 
L 
