MADEEPOBA. 119 



branches, rarely proliferous except at the margin of the colony, where the corallites are more 

 elongate and irregular. The radial corallites have typically a flattened, not a gutter-shaped 

 lip, but the latter form is also present, more distinctly marked in some specimens than in 

 others ; the septa are also better developed. 



Indo-Pacific Ocean : Singapore, Great Barrier Reef area, Tongatabu. 



a, b. ? Dr. Mantell's Coll. 41. 1. 13. 12 & 15. 



c. Tongatabu. J. J. Lister, Esq. [P.]. 91. 3. 6. 10. 



d. Singapore. J. P. Davies, Esq. [P.] . 82. 9. 25. 3. 



e. ? Purchased. 40. 5. 15. 12. 



/, g. ? ? 93. 4. 7. 106 & 1U7. 



h. Port Denison. Saville-Kent Coll. 92. 6. 8. 164. 



116. Madrepora prostrata. 



Madrepora prostrata, Dana, Zoophytes, p. 447, pi. xxxiii. fig. 1 ; M.-Edwards & Haime, Coralliaires, 

 t. iii. p. 156 ; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. p. 18 ; ? Ortmann, Zool. JB. 1888, 

 Bd. iii. p. 153 ; ibid. 1889, Band iv. p. 508 (rKm Quelch, ' Challenger ' Reef Corals, p. 163 ; non 

 Bassett-Smith, Ann. Mag. N. H. 1890, vol. vi. p. 454). 



Corallum prostrate, spreading horizontally from a lateral attachment. Branches 

 remotely coalescing, not flattened below, with few branchlets and the corallites all immersed. 

 On the upper surface the branches are cylindrical, nearly simple, 6 mm. thick, blunt at the 

 apex. Axial corallites short, about 1*5 mm. broad. Radial corallites crowded, spreading 

 nearly at right angles, labellate, with broad, much flattened lip. Star distinct, the directive 

 septa broadest. {Dana.) 



The specimen from Fiji recorded by Ortmann differs from the above description of Dana 

 in several respects and may prove to be distinct. The under surface is flattened, and the 

 branches fused together and provided with a few conical twigs and pustules without aperture 

 and also a few immersed corallites. The branchlets on the upper surface do not exceed 

 1'8 cm. in length, and are frequently 1 cm. thick at the base, tapering, but with a blunt apex. 

 Axial corallites 2 to 2"5 mm. broad, scarcely exsert. Radial corallites very short, spreading, 

 bursiform, with the wall a little thickened ; lip not elongate, nearly 2 mm. diameter. Star 

 prominent. 



The form from the Great-Barrier Reef does not altogether agree with Dana's descrip- 

 tion, and looks in some respects like a diminutive form of M. millepora. The corallum 

 is open corymbose, flattened above and oblique at the sides, but with very few fusions, or 

 forms flattened, plate-like masses with short branchlets on the upper surface. In the latter 

 case the corallum is 33 cm. thick, the main branches confluent and in parts almost solid. 

 The branchlets are simple, or 2 to 5 arise from a common base from the upper surface of a 

 branch; length 2'5 to 3'2 cm., diameter 7 mm. Corallites similar to those of M. millepora, 

 but smaller, length 1 to 1*5 mm., diameter 1"5 to 2 mm. 



Pacific Ocean : Fiji, Sulu Sea, Great-Barrier Reef. 



b2 



