MADEEPOEA. 63 



between on the branchlets ; such immersed corallites are more numerous below and on the 

 inferior surface of the branches. Sometimes they are also numerous on the superior surface 

 to within 5 cm. of the apex, and have a few short, labellate corallites scattered between at 

 intervals of 3 to 6 mm. The immersed corallites are smaller than in Dana's type, and rarely 

 exceed 0-7 mm. in diameter. Corallum moderately porous above, but very dense and stony 

 in the older parts; the surface dense and strongly echinulate, a little reticulate above; wall 

 strongly costate, not very fragile, and the larger corallites have the lip a little thickened. 

 Star indistinct in the majority of the radial corallites, the directive septa being narrow and 

 the others rudimentary. 



This species shows a strong affinity with Lepidocyathus in the form of the corallites and 

 the condition of the septa. 



A note on one of the ' Challenger ' specimens indicates that this is the most abundant 

 reef -forming species at Mactan Island, Philippines. 



A fragment from Samboangan, referred by Quelch to M. prostrata, does not belong to 

 that species, but appears to be a marginal fragment of M. aspera ; the lateral portions of a 

 colony probably extend in a subhorizontal plane. 



Apical portions of a colony which get broken readily become fused again to the colony, 

 as has been described by Studer for M. formosa and other species. 



Pacific Ocean : Philippines, New Hanover, Great-Barrier Reef area, Fiji. 



a, b. Mactan Island. H.M.S. ' Challenger.' 86. 12. 9. 230, 



c-e. Mactan Island. H.M.S. ' Challenger.-" '93. 10. 16. 26 to 28. 



?/. Samboangan. H.M.S. ' Challenger.' 86.12.9.219. ( = M.;?ros/rate, Quelch.) 



g. Warrior Island. Saville-Kent Coll. 92. 6. 8. 31. 



h. Rocky Island. Saville-Kent Coll. 93. 6. 8. 240. 



44. Madrepora manni. 



Madrepora manni, Quelch, ' Challenger' Eeef Corals, p. 150, pi. ix. fig. 1. 

 Madrepora demani, Eehberg, Abh. nat. Ver. Hamburg, 1892, Bd. xii. p. 33. 



Corallum arborescent, laxly branched, subprostrate. Branches terete, elongate, often 

 arranged in pairs arising either just above or below the lateral margin, arcuate, all ultimately 

 directed upwards; they are 8 to 10 cm. or more in length and I'l to TS cm. thick at the 

 base, very gradually tapering to 5 or 6 mm. near the apex, then frequently contracted to a 

 rather small axial corallite. Axial corallites 2 to 3 mm. diameter and 1 to 2 ram. exsert; 

 wall strongly costulate, thick, and little porous ; septa in two narrow cycles, but the second 

 cycle sometimes nearly as broad as the other. Radial corallites broadly labellate, the upper 

 half of the wall wanting, very crowded, arranged at right angles to the branch, 2 mm. long ; 

 lip a little flattened, fragile, 2 mm. diameter near the apex in the more prominent corallites, 

 but showing all stages from immersed through short acicular and narrow labellate to the 

 more fully developed form. The corallites become very" short or immersed on the inferior 

 surface of the branches, aperture varying from 0'5 to 1 mm. in diameter, septa scarcely 



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