MADEEPOEA. 167 



lateral ones ; others are slender and angular, an inch or more long, with a few distantly 

 scattered and rather large lateral cells. Terminal corallites somewhat exsert, thick, sub- 

 conical, being thickened below. Cells with 6 septa and a thick margin. Lateral corallites 

 few, tuberculiform, thickened at base, with a simple tubular lip ; cells but little smaller than 

 the terminal ones, with 6 septa distinct. On the lower side of the coral there are neither 

 cells nor branchlets. Ccenenchyma very porous and open, spongiform, scabrous, without 

 distinct striations even on the corallites. Breadth of coral 5 inches; height 1'5 ; diameter of 

 larger branches -28 ; of cells '05." (Verrill.) 



Bonin Islands. 



C. Corallum cespitose. 



179. Madrepora violacea. (Plate XI. fig. A.) 

 Madrepora violacea, Brook, Ann. Mag. N. H. 1892, vol. x. p. 465. 



Corallum cespitose or subcorymbose from an incrusting base. Colony about 9 cm. high 

 and 12 cm. in diameter. Branches short, stout, and much divided, 1 to TS cm. diameter at 

 the base, somewhat angular owing to crowding; main divisions 2 '5 to 3"5 cm. long, over 1 cm. 

 diameter at a point 1 cm. below the apex. Axial corallites 2'5 to 3'5 mm. diameter, usually 

 about 1*5 mm. exsert, cylindrical or subconical with a rounded margin, wall dense and thick ; the 

 star consists of two cycles of moderately-developed septa, the directives not appreciably 

 broader than the other primaries. Radial corallites chiefly stout, spreading tubular, with 

 smaller tubular, nariform or subimmersed ones between ; sometimes the stout corallites are 

 arranged in subregular rows with small ones between, at others the small corallites are few 

 and scattered. The stout corallites often have the inner part of the wall a little shorter than 

 the outer and the aperture is then oval, the margin is distinctly rounded, diameter 2 to 2'5 mm., 

 length 2 to 4 mm. ; many of the^ longer ones bear buds, others form short twigs 6 mm. or 

 more in length. The stout corallites have the directive septa more prominent than the others 

 and one or two cycles may be moderately developed, but in other cases the star is scarcely 

 recognizable. Corallum rather dense ; surface and wall finely echinulate, not striate. 



A specimen from the Great-Barrier Reef differs from the type in one or two points. The 

 apex of the stout tubular corallites is often oblique owing to the shortness of the inner part 

 of the wall or occasionally the form may be dimidiate. The septa are better developed than 

 in the type, and especially in the numerous short open corallites near the base of the branches 

 and on the under surface ; the directive septa almost meet in the middle line. 



Pacific Ocean : Fiji, Great-Barrier Reef. 



a. Fiji. F. M. Rayner, Esq. [P.]. 62. 2. 4. 31. (Type.) 



b. Green Island, Great-Barrier Reef. Saville-Kent Coll. 92. 6. 8. 294. 



z 2 



