MADEEPORA. 85 



to 2 mm. ; the stouter ones bear buds. The wall is moderately thick excepting in its inner 

 partj which is thin and often not quite so prominent, giving an elliptical aperture. Usually 

 at a point 1 to 1'5 cm. below the apex of a branch the corallites become shorter and verruci- 

 form, but scarcely any are completely immersed, even at the base of the branches. Star 

 distinct, but not very broad ; it consists of 12 septa, with the outer directive usually broader 

 and stouter than the others. Corallum dense ; surface and wall closely and finely echinulate ; 

 margin distinctly rounded in all except the youngest corallites. 



Indian Ocean : Diego Garcia. 



a b,?c. Diego Garcia. G. C. Bourne, Esq. [P.]. 91. 4. 9. 5, 9 & 10. (Types.) 



B. Corallum corymbose, more rarely cespitose : corallites elongate, with dense wall 



and often acuminate apex. 



76. Madrepora appressa. 



Heteropora appressa, Ehrenberg, Corallonth. d. roth. Meeres, p. 109. 



Madrepora appressa, Studer, Mitth. naturf. Ges. Bern, 1880, p. 22 {non Dana, M.-Edwarda & 

 Haime, &c.). 



Corallum corymbose (?), the under surface of the branches horizontal and fused into 

 flattened plates, with a few thick conical corallites below, most of which are lateral, and a few 

 immersed ones scattered over the general surface". Branchlets on the upper surface about 

 4 to 6 cm. long and 1 to 1-5 cm. thick at the base. Axial corallites 2 to 2'5 mm. diameter, 

 with rounded margin and small aperture. Radial corallites elongate and appressed with 

 rather thick curved wall, up to 8 mm. in length and 2 mm. thick, the more elongate ones 

 have a slit-like aperture and are proliferous : all are very irregularly placed. The usual form 

 is hooked labellate, with a thick blunt and frequently incurved apex ; those below are short 

 or immersed ; aperture 1 mm. ; 6 primary septa, prominent. Corallum moderately porous, 

 but firm ; surface dense and echinulate, or tabulato-echiuulate with elongate pits between ; 

 wall dense and echinulate, not striate. 



This species differs from the form which I believed to represent Dana's M. appressa in 

 its more robust habit, and particularly in the longer and stouter radial corallites with an 

 elongate, thick and blunt apex. It may, however, be only an individual variation, and I have 

 not seen elsewhere any specimen which agrees with it completely. 



Habitat of the type specimen {Berlin Museum) not recorded. 



? a. Evans Bank, 15 fath., Arafura Sea. H.M.S. 'Penguin.' 92.4.5.3. 



77. Madrepora assimilis. (Plate XX. fig. A.) 



Madrepora appressa, Dana (non Ehrenberg), Zoophytes, p. 457, pi. xxxiv. fig. 5, pi. xxxi. fig. 8; 

 ? Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 42 ; ? Studer, Mitth. naturf. Ges. Bern, 1880, 

 p. 22; Quelch, ' Challenger' Reef Corals, p. 163; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. 

 p. 12. 



N 



