150 MADEEPORARIA. 



In one of the type specimens of Ehreuberg the outer part of the wall of the radial 

 corallites is not so thick as usual, and in some cases is quite thin, and in some specimens the 

 branches are much more subdivided than in others. 



This and the follomug species are sometimes very difficult to separate and it may be that 

 both are varieties of one species. M. pyramidalis is readily distinguished from M. seriata 

 by the form of the branchlets, but there appears, so far as I can judge, to be no constant 

 difference in the corallites. 



Indian Ocean: Red Sea, Seychelles, Mauritius, Ceylon, Mergui Archipelago, Great- 

 Barrier Reef, ?Tongatabu. 



a. Red Sea. Dr. Klunzinger [C.]. 86. 10. 5. 42. (= M. pallida, Klz.) 



?A. Tongatabu. J. J. Lister [P.]. 91.3.6.15. (Young colony.) 



c. Low Woody Island. Saville-Kent Coll. 92. 6. 8. 146. 



d. Capricorn Islands. Saville-Kent Coll. 92. 6. 8. 147. 



e. Troughton Island. H.M.S. 'Penguin.' 92, 1. 16. 6. 



157. Madrepora pyramidalis. 



Madrepora pyramidalis, Klunzinger, Korallenth. d. roth. Meeres, Th. ii. p. 12, pi. i. fig. 2, ? pi. Iv. fig. 6, 

 pi. ix. fig. 7, pi. X. fig. B, pi. ii. fig. 3 ; Mobius, Beitr. z. Meerosfauna Mauritius, p. 45 ; Duncan, 

 Journ. Linn. Soc. London, 1886, vol. xxi. p. 20 ; Ortmann, Zool. JB. 1888, Bd. iii. p. 151 (part.). 



CoraUum low cespitose or incrusting. Branches pyramidal, rather crowded, so as to 

 become angular below, but conical above, tapering rapidly to a blunt apex ; branches little 

 divided unless near the margin of a colony, and budding branchlets are not of frequent 

 occurrence; branches 3 to 4 cm. high and 8 to 10 mm. diameter at a point 1*5 cm. from 

 the apex. Radial corallites much appressed, rather unequal, chiefly with the inner part of 

 the wall undeveloped. In other respects the species agrees closely with M. seriata, Ehrb. 



Var. depressa, Klunzinger, op. cit. pi. ii. fig. 3. 



CoraUum incrusting, without branches ; corallites all short, thick, tubular, those which 

 represent axial corallites recognizable by their larger size. One of Klunzinger's specimens in 

 the Berlin Museum consists of a colony in which the branches at one side are of the usual 

 type, but on the other gradually decrease in length until they reach the incrusting condition 

 of var. depressa. The specimens referred by Bassett-Smith to this variety agree with the 

 figure, but form large incrusting masses over an irregular surface of considerable extent. It 

 is, of course, possible that they belong to M. smithi, with which they occur on the Tizard 

 Bank ; probably in an incrusting condition the two species could not be separated. 



Var. corymbiformis. 



CoraUum corymbose with a solid base. Branchlets on the upper surface of the charac- 

 teristic form, but united together by the solid basal structures, 2 to 3*5 cm. long and about 



