138 MADEEPOEAEIA. 



a. Koseir, Red Sea. Dr. Kluuzinger [C.]. 86. 10. 5. 5. 



*. Maldive Islands. Colonial Exhibition. 86. 11. 22. 8. 



c, d. Diego Garcia. G. C. Bourne, Esq. [P.]. 91. 4. 9. 1 & 8. 



e. Thursday Island. Saville-Kent Coll. 92. 6. 8. 297. 



Var. parvula. 



a. Diego Garcia. G. C. Bourne, Esq. [P.]. 91. 4. 9. 11. 



'>b,c. ? ■ ? 93. 4. 7. 119 & 136. 



b. Radial corallites not wider at the apex. 



* No proliferous corallites excepting such as indicate new branches. 



140. Madrepora fruticosa. (Plate XVIII. fig. A.) 

 Madrepora fruticosa. Brook, Ann. Mag. N. H. 1892, vol. x. p. 457. 



CoraUum bushy cespitose, upper surface hemispherical ; 18"5 cm. high and 25 cm. wide, 

 from a round incrusting base about 12*5 cm. in diameter. Marginal branches very short and 

 reflexed, others rapidly increasing in length towards the centre ; middle branches 9'5 cm. 

 long and 2 cm. thick near the base, angular below ; the majority are bi- or trifid, each division 

 being usually again divided; the majority of the divisions are 15 cm. diameter and have a 

 blunt apex ; apices about 3 cm. apart. Axial coraUites 4 to 5 mm. diameter, sub-hemi- 

 spherical ; wall very porous. Radial corallites prominent, spreading, and relatively regular, 

 a little compressed, chiefly tubiform with the inner part of the wall more or less incomplete ; 

 the inner part always thin, the outer usually very thick but porous, margin plane; length 3-5 

 to 5 mm., diameter 2*2 to 2-5 mm. ; the outer part of the wall is convex in those corallites 

 situated some distance below the apex, and the inner part of the wall is almost absent ; 

 nearer the base the corallites are quoit-shaped, becoming completely immersed on the main 

 divisions. A few small thin-walled or subimmersed corallites are scattered between the 

 more prominent ones, but are not sufiSciently numerous to destroy the general appearance of 

 regularity. Short proliferous corallites are of frequent occurrence, and may be first recognized 

 by the fact that the inner part of the wall becomes as prominent and as thick as the outer. 

 CoraUum porous ; surface spongy-echinulate ; wall striato-reticulate at first, becoming 

 echinulate in linear series below. 



The star of the radial corallites consists of a primary series of septa, of which the direc- 

 tives are well developed, and, excepting near the apex of a branch, of a more or less complete 

 second cycle. 



This species difibrs in a marked degree from M. spectabilis in habit and in the general 

 appearance of the middle branches, but the radial corallites have here almost precisely the 

 same form and arrangement throughout the colony as occurs on the marginal divisions of 

 M. spectabilis. On this account the two forms may ultimately prove to be varieties of one 

 species. In habit the species approaches M. erythraa, Klz. 



