MADEEPOEA. 101 



the branchlets of the upper surface^ and the occurrence of numerous spreading tubular 

 corallites on the under surface. There are several specimens in the collection of the British 

 Museum which agree with Dana's figure in these respects, and at first sight there appears 

 little afiinity to specimens of M. cytherea from Tahiti, the original habitat. The colony is 

 umbellate rather than vasiform, and is flat on the upper surface excepting in very small 

 colonies where the central branches are not so long as the others. That it is not the 

 ordinary young form of M. cytherea appears to be shown by the fact that in specimens of 

 25 cm. diameter scarcely any proliferous corallites occur, whereas in the normal specimen 

 oi M. cytherea, of 30 cm. diameter, proliferous corallites are numerous and the corallites of 

 the under surface arc dilated verruciform. It appears, therefore, more convenient to regard 

 it as distinct. 



Corallum vasiform or umbellate, pedicellate, flat above excepting when young, under sur- 

 face oblique. Height of the corallum 15 cm., diameter 25 cm. ; diameter of pedicel 6 to 

 8 cm. The outer branches are about 1'2 cm. thick and 9 to 12 cm. long, crowded and a little 

 compressed laterally. On the outer or under surface they bear numerous spreading, tubular, 

 often proliferous, corallites, 1'5 to 2 mm. diameter and 2 to 4 mm. long if simple, but the 

 majority are in some specimens more elongate and bear buds. On the pedicel these corallites 

 form short tapering branchlets spreading at right angles and often 1 cm. in length. The 

 interval between these twigs and proliferous corallites is occupied by short-lipped or immersed 

 ones. The branchlets on the upper surface are usually arranged in groups of 2 to 6 from a 

 common base ; those in the centre are longest, and the apices are about 8 mm. apart ; length 

 1'5 to 4 cm., diameter 6 mm. or a little over, apices rarely proliferous unless near the 

 margin of the colony. Axial corallites 2 mm. diameter, 1 to 2 mm. exsert, cylindrical, with 

 porous and strongly striate wall. Radial corallites spreading tubo-labellate or gutter-shaped, 

 with very thin fragile and reticulate wall ; length 2 to 3 mm., diameter 1 to 1-5 mm., 

 becoming shorter and finally immersed below. The corallites are not so spreading on the 

 marginal branchlets as nearer the centre. Star scarcely at all developed, usually only the 

 directive septa are recognizable. Corallum very porous ; surface striato-echintdate ; wall 

 striato-reticulate, echinulate near the base. 



,}■ 



Indo-Pacific Ocean: Singapore, Diego Garcia, ? Tahiti. 



a. Singapore ? W. E. Hands, Esq. [P.]. 50. 1. 16. 1. 



6. Singapore. T. Ingall, Esq. [P.]. 57.4.6.1. [-Types. 



c, d. Diego Garcia. G. C. Bourne, Esq. [C.]. 91. 4. 9. 6 & 7. 



?e. Tahiti. H.M.S. 'Challenger.' 86.12.9.410. 



{■=M. cytherea, Quelch, part.) 



/. ? Purchased. 40. 5. 29. 1. 



y. ? ? 93. 4. 7. 164. 



h. ? ? 49. 5. 15. 11. 



i-k. ? ? 93. 4. 7. 124, 125 & 131. 



