44 MADEEPOEAEIA. 



The specimens referred by Studer to M. brachiata appear to differ only from M. formosa 

 in having stouter branches, and I do not think the two forms are specifically distinct. Dana 

 was of opinion that the diameter of the branches in any given species is practically constant, 

 but I doubt if diameter alone has more than a minor value in the discrimination of species. 



Indo-Pacific Ocean : Fiji and Sulu Sea, Torres Straits, New Ireland, New Hanover, 

 Sumatra, Singapore, ? Ceylon. 



a. Nias Island, Sumatra. Purchased. 85. 9. 3. 1. 



b. Thursday Island. Saville-Kent Coll. 92. 6. 8. 80. 



22. Madrepora pulchra. (Plate XXVIII. figs. A, B, C.) 



Madrepora cribripora, Bassett-Smith (non Dana), Ann. Mag. N. H. 1890, vol. vi. p. 452. 

 Madrepora orhipora, Dana, var., Eidley & Quelch, in H. 0. Forbes' Naturalist in the Eastern Archi- 

 pelago, London, 1885, p. 44. (The specific name is probably a misprint for cribripora.) 

 Madrepora pulchra. Brook, Ann. Mag. N. H. 1891, vol. viii. p. 468. 



Corallum arborescent, branches 1*2 to 1"8 cm. thick, terete, often bearing radiating 

 clusters of branchlets at intervals of 2"5 to 5 cm. ; branchlets elongate, simple or subsimple, 

 3'5 to 9 cm. long, 8 to 12 mm. thick, gradually attenuate; the angle of the branchlets 

 varies from 30° to 90°. Axial corallites cylindrical, 3 mm. diameter, about 2"5 mm. exsert, 

 those of the branchlets rather smaller. Radial corallites all spreading at right angles, 

 excepting near the apex of a branchlet ; all are short, tubular, a little variable in length, and 

 exhibiting considerable variation in diameter. Length subimmersed to 1"5 mm., diameter 

 0*75 to 2 mm. The aperture of the larger corallites is usually a little oblique, and in some 

 cases the inner part of the wall is only slightly developed, whilst the outer is elongate, giving 

 a tubo-labellate form ; the inner part of the wall is, however, rarely absent, excepting in the 

 older parts of the corallum, where the majority of the corallites are immersed. The outer 

 part of the wall is usually a little thickened in the larger corallites, but the aperture remains 

 over 1 mm. in diameter. The star of the axial corallites consists of six well-developed sub- 

 equal primary septa, the second cycle is rudimentary ; in the radial corallites the star is 

 rudimentary, the directive septa are usually recognizable, and sometimes two or, more rarely, 

 four others. Corallum very porous, surface reticulate and echinulate ; wall striato-reticulate, 

 echinulate in the case of the stouter corallites, 



Var. stricta. (Plate XXVIII. fig. B.) 

 The specimens from the Tizard Bank referred to M. cribripora by Bassett-Smith appear 

 referable to this species. The branches and branchlets are relatively more slender and 

 tapering, and the larger corallites more distant. They are less distinctly tubular than in the 

 type, and rarely over 1'3 mm. diameter ; the inner part of the wall is imperfectly developed. 

 The septa are better developed in the radial corallites, but the second cycle is rarely complete 

 even in rudiment, and all are narrow excepting the directives. The whole texture is firmer, 

 and the surface is closely reticulate. 



