100 MADEEPORAEIA. 



2 mm. in diameter, and 2 to 3 mm. exsert ; wall a little thickened, margin not rounded. 

 Radial corallites 2 to 4 mm. long, and 1 to 1"5 mm. diameter, chiefly labellate, with small 

 often styliform lip, but the larger ones are half-tubular as in M. corymbosa ; the upper 

 corallites are very unequal in length and diameter, and are usually more appressed than in 

 M. corymbosa, the lower ones and those on the main divisions are mostly immersed. Star 

 indistinct, the inner directive septum usually recognizable, and sometimes the other primaries 

 also, particularly in the immersed corallites. Corallum rather porous ; surface subreticulate, 

 ribbed and echinulate ; wall strongly striate and echinulate. 



Var. globata, Klunzinger. 

 Colony massive and convex from an incrusting base. 



A specimen from Diego Garcia forms a large rounded subvasiform colony, the vase 

 being produced as in M. arcuata by the overlapping and fusion of the posterior lobes of an 

 originally arched and flabellate specimen. In the character of the under surface this speci- 

 men comes nearer to specimens from Tahiti than to those obtained by Klimzinger from the 

 Red Sea. 



Generally speaking the Pacific form has the under surface covered with short usually 

 much dilated tubular corallites, and those on the upper surface have a rather porous wall. In 

 Red Sea specimens the under surface has no dilated corallites, and the majority are immersed 

 or subimmersed J on the upper surface the wall of the radial corallites is dense and firm. 



The species forms extensive terraces in the Red Sea, and sometimes is very difficult 

 to distinguish from certain forms of M. corymbosa. Tahiti specimens are vasiform and 

 differ from many Red Sea specimens in various details, particularly in the dilated corallites 

 of the under surface and the extremely numerous proliferations on the upper surface. 



Indo-Pacific Ocean : Tahiti, Solomon Islands, Singapore, Ceylon, Diego Garci 

 Mauritius, Red Sea. 



a. Red Sea. Dr. Klunzinger [C.]. 86. 10. 5. 31. 



b, c. Tahiti. H.M.S. ' Challenger/ 85. 2. 1. 19 & 86. 12. 9. 409. 



d. Singapore. Purchased. 78. 6. 6. 14. 



e. Solomon Islands. Dr. Guppy [C.]. 84. 12. 11. 24. 



?/. Diego Garcia. G. C. Bourne, Esq. [C.]. 92. 5. 29. 1. 



g, h. Ceylon. Haeckel Coll. 92. 12. 15. 19, 27 & 29. 



i. ? ? 93. 4. 7. 116. 



j. ? Bowerbank Coll. 77. 5. 21. 183. 



*. ? ? 93.4.7.126. (Var.) 



92. Madrepora armata. (Plate X. figs. A, B.) 



Madrepora spicifera, Dana, Zoophytes, p. 443 (part.), pi. xxxiii. figs. 4 & 4 a only. 

 ? Madrepora cytherea, Quelch, 'Challenger' Reef Corals, p. 165 (part.). 

 Madrepora armata. Brook, Ann. Mag. N . H. 189i!, vol. x. p. 452. 



The small specimen figured by Dana under the name M. spicifera does not appear 

 to belong to that species, but, as Dana suggested, may be a young form of M, cytherea. It 

 differs from that species in two important points, viz. : the scarcity of proliferous corallites on 



