MADEEPOEA. 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. cnspidata. 

 A variety from the Macclesfield Bank differs from the type in having normal twigs on the 

 upper surface 1 to IS cm. long and 3 to 4 mm. thick, distinctly tapering, simple or more 

 usually bi- or trifid ; corallites nearly all immersed j 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.). 

 /. Eagle Island, 10 fathoms, Amirante Islands. H.M.S. 'Alert.' 82. 10. 17.141. 



(Proliferous var.) 

 ^. 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. 



I to 5. 



?n. Evans Bank, 15 fathoms, Arafura Sea. H.M.S. 'Penguin.' 92. 4. 5. 4. 



Var. cuspidata. 



a-/. Macclesfield Bank. H.M.S. 'Penguin. 92. 10. 17. 6 to 



10 & 13. 

 "ig, h. Macclesfield Bank, 13 fathoms. H.M.S. ' Penguin.' 92. 10. 17. 



II & 12. 



53. Madrepora oligocyathus. (Plate VII.) 



Madrepora oUgocyathm, Brook, Ann. Mag. N. H. 1892, vol. x. p. 460. 



Corallum forming a fan-shaped and pedicellate half- vase; length 60 cm., breadth 53 cm., 

 diameter of pedicel 7 cm. 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 Vo cm. 

 long and 5 mm. diameter at the base, somewhat tapering, nearly all are a little appressed. 



