MADEEPOEA. 128 



121. Madrepora cribripora. 



Madrepora cribripora, Dana, Zoophytes, p. 470, pi. 31. fig. 1 ; M.-Edwards & Haime, CoraUiaires, t. iii. 

 p. 137 ; Eathbun, Proc. U.S. Nat. Mus. 1887, vol. x. p. 15 ; ? Duncan, Journ. Linn. Sec. Lond. 

 1886, vol. xxi. p. 20 {non Bassett-Smith, Ann. Mag. N. H. 1890, vol. vi. p. 452). 



Arborescent or cespito-arborescent, spreading ramose ; branches neatly terete, 8 to 10 mm. 

 thick; branchlets long (some 7*5 cm.), attenuate and subacute. Corallum scabrous, very 

 porous; axial corallites stout (2 to 3 mm.), quite long, striate; the radial ones very short, 

 round-nariform, fragile, a little crowded ; cell open ; star obsolescent, one inner lamella 

 prominent. [Dana.) 



Three specimens in the collection from Tongatabu appear referable to this species, but 

 differ in several points from the above description. The one which comes nearest to the type 

 in habit (a) is a small cespito-arboresceut clump about 14 cm. high and 19 cm. wide. The 

 branches are 8 to 11 cm. long, and about 1 cm. thick, or slightly more, some are forked near 

 the base, arcuate, and scarcely subdivided, others bear 3 to 7 branchlets. All are subterete, 

 and taper rather rapidly to a prominent axial corallite, which is 2-5 to 3 mm. diameter and 

 3 mm. exsert. The radial corallites are wide, half-tubular or labellate, all spreading almost at 

 right angles, 1"5 to 2 mm. wide or rather more, and 1 to 2 mm. long ; wall thin, and strongly 

 striato-reticulate and echinulate. A few which have a thick wall and almost circular aperture 

 indicate new proliferations. All the corallites become shorter and finally immersed on the 

 lower and under parts of the branches. The star consists of 12 narrow subequal septa in axial 

 corallites ; in the radial corallites there are only 6, and the inner directive is usually con- 

 siderably broader than the others. Corallum very porous and fragile ; surface reticulate and 

 rather distantly but distinctly echinulate. 



The other specimens [b and c) consist of single branches of a variety which is evidently 

 arborescent rather than cespitose in habit. Branches 20 to 25 cm. long, sinuous, 1 cm. thick, 

 very gradually tapering, laxly and spreadingly divided ; branchlets 3 to 8'5 cm. long, spreading, 

 simple or subsimple, nearly as thick as the branch from which they rise. In the upper branchlets 

 the corallites resemble those already described, but they are subequal, nearly 2 mm. long; 

 shorter or subimmersed ones are of rare occurrence. The lower and usually shorter branchlets 

 differ entirely from the above description. The axial corallites are 2'5 to 3 mm. diameter, but 

 scarcely exsert, in no case over 1'3 mm.; cup open, with 12 septa. Radial corallites all very 

 short, round nariform with a curved and relatively thick and firm wall, 2 mm. diameter and 

 about 1 mm. long ; wall strongly and rather distantly echinulate, sometimes substriate. In 

 the Palm-Island specimen one of the axial corallites contains 24 septa. 



Dana's specimens were obtained on a reef near Rewa ( Viti Levu), where the waters are 

 much freshened by the river which empties near, and this was almost the only species occurring 

 on that part of the reef. 



Indo-Pacific Ocean : Tongatabu, Fiji, Great-Barrier Reef, ? Mergui Archipelago. 



a. Tongatabu. J. J. Lister, Esq. [P.]. 91. 3. 6. 1. 



b-c. Tongatabu. J. J, Lister, Esq. [P.]. 91. 3. 6. 2 & 3. (Var.) 



d. ? ? 41.2.23.39. 



e. Palm Island. Saville-Kent Coll. 92. 6. 8. 299. 



