116 MADREPOEARIA. 



corallites of the central branchlets and those of the marginal ones. The septa are not well 

 developed in the radial corallites, usually only the directives are recognizable, unless in im- 

 mersed corallites, and the outer directive septum is generally either broader or stouter than 

 the inner one. 



A. Corallum corymbose or bushy. The radial corallites thin-walled and prominent 

 nearly to the bases of the branchlets. 



113. Madrepora imbricata. 



Beteropora imbricata, Ehrenberg, CoraUenth. d. roth. Meeres, p. 112 ; Dana, Zoophytes, p. 722. 



The type specimen consists of several fragments which apparently form part of a vasi- 

 form colony. The main branches are not much fused together, and on the under surface 

 bear elongate, appressed, tubular twigs, often 2 cm. long and only 3 mm. thick at the base, 

 provided with lateral subimmersed buds. The branches on the upper surface are 8 to 10 mm. 

 thick, and give rise to ascending branchlets 3 to 4 cm. long and about 6 mm. thick near the 

 base. Axial corallites 1'5 to 2 mm. diameter, 1 mm. exsert, wall a little thickened, primary 

 septa moderately developed. Radial corallites crowded, broad, flattened labellate, spreading, 

 but not at right angles, equal or subequal, 2 mm. long and often 2 mm. broad across the lip, 

 becoming shorter and subimmersed on the stouter parts. Star of the radial corallites not 

 developed, frequently only the lower directive septum is recognizable. CoraUum moderately 

 porous but vitreous ; surface dense, echinulate ; wall striate and echinulate. 



This species appears to have been overlooked and is not included in the work of Milne- 

 Edwards. It diflers chiefly from M. millepora and M. convexa in the less coalescent branches 

 and the condition of the under surface. 



Habitat not recorded. [Berlin Museum.) 



114. Madrepora millepora. 



Heteropora miilepora, Ehrenberg, CoraUenth. d. roth. Meeres, p. 109. 



Madrepora millepora, Studer, MB. Akad. Wiss. Berlin, 1878, p. 528 ; Studer, Mitth. natur. Ges. Bern, 



1880, p. 20 ; Ortmann, Zool. JB. 1889, Bd. iv. p. 508. 

 Won Madrepora millepora, Dana, Zoophytes, p. 446, pi. xxxiii. fig. 2 ; ? M.-Edwards & Haime, Coral- 



liaires, t. iii. p. 155 ; ? Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 42 ; Quelch, ' Challenger ' 



Keef Corals, p. 157. 

 ^Madrepora convexa, Ortmann, Zool. JB. 1888, Bd. iii. p. 153 (part.); ibid. 1889, Bd. iv. p. 508. 



Corallum corymbose and pedicellate, flattened below, where the branches are confluent 

 and bear immersed corallites and a few appressed or spreading conical twigs. In Ehrenberg's 

 type the lateral branches of the colony are not preserved. The branchlets on the upper 

 surface are terete, 5 to 7'5 cm. long and about 7 mm. diameter, simple or more usually 

 subdivided into clusters, especially near the margin of a colony. The distal divisions are 2 to 

 4 cm, long, only slightly tapering, with the apices obtuse. Axial corallites cylindrical, 2 mm. 



