1898.] CORALS or the south pacitic. 259 



out at rigbt angles to it, being often 20-30 cm. long by about 10 

 cm. broad at the base and tbe corallum 3 cm. tbick ; the end twigs 

 are incompletely fused. On the upper surface are a number of 

 conical elevations, really formed by the end twigs having turned 

 upwards and having budded out fresh twigs at their bases ; they 

 vary largely accordiag to position, but are seldom more than 3 cm. 

 high by l*5-3 cm. broad at the base. The axial corallites are 

 2*5-3 mm. in diameter, and are seldom more than 1 mm. exsert ; 

 the opening of the calice is about 1 mm. broad. The sides of the 

 cones and the upper surface of the corallum are covered by nari- 

 form or tubi-nariform corallites about 1'5 mm. in diameter by 2-3 

 mm. in length; they are generally about 3 mm. apart, and the 

 intervals between are occupied by small immersed or subimmersed 

 corallites. The primary and secondary septa are generally distinct 

 in the axial corallites, the directives nearly meeting in the middle 

 line, the secondary much narrower and thinner ; generally in the 

 radial corallites six very narrow thick septa can be distinguished. 

 The under surface of the corallum is covered with round immersed 

 corallites about 1 mm. in diameter and 1-3 mm. apart ; the 

 primary septa are distinct, the directives more prominent. The 

 corallum is formed by very coarsely reticular elements, covered on 

 the upper surface by low granular spines, which may form stria- 

 tions ; the under surface of the plates seems to be thickened by a 

 true coenenchymatous formation, showing very clearly in section 

 two elements, the one parallel and the other perpendicular to the 

 under surface. 



Rotuma ; outer reef. 



This is by far the most abundant coral on the reefs of Eotuma, 

 and is found in places covering as much as 25 per cent, of its sur- 

 face. In general appearance its upper surface resembles M. smithi, 

 but the colony is always very distinctly pedicellate. 



4. Madrepoea eobusta Dana (19). 

 Eotuma ; 4 fathoms. A fragment. 



5. Madeepoea pulchea Brook (22). 

 Var. alveolata Brook. 



I have referred, after some hesitation, a specimen to this species 

 and variety. The ends of many of the branches have been killed, 

 apparently by sand, and the remaining branches are stunted and 

 much divided near their apices. 



Eotuma ; boat channel. 



6. Madeepoea atjsteea Dana (35). 



A much-branched specimen covered with tubi-nariform radial 

 corallites. The surface of the corallum is finely echinulato-striate, 

 and there are a few small obsolescent calicles between the large 

 radial corallites. The primary septa in the radial corallites are 

 deep but distinct. 



Eotuma ; 3 fathoms. 



17* 



