MADREPORA. 61 



nariform or short tubular, rarely immersed corallites on the under surface. Branchlets on 

 the upper surface very numerous, erect, very short and stunted, arranged singly or in groups 

 of 2 to 6 in one mass ; length 5 to 10 mm., usually not over 7 mm., diameter 4 to 6 mm. if 

 single, but up to 1-5 cm. if clustered. Axial corallites 2 to 3 mm. diameter, not over 1 mm. 

 exsert ; wall thick, septa very prominent. Radial corallites crowded, round and spreading 

 nariform or sublabellate, wall thick, aperture wide; diameter 1-5 to 2 mm., length rarely 

 2 mm. The septa are arranged in two moderately developed cycles, the directives are 

 broadest. The interval between the branchlets is occupied by immersed corallites. Corallum 

 rather dense ; surface echinulate ; wall striate and echinulate. 



The species bears a general resemblance to flattened specimens of M. affinis. 



Tizard Bank. 



a. Tizard Bank, 5 fath. H.M.S. ' Rambler.' 89. 9. 24. 117. (Type.) 



H. Corallum bushy. Radial corallites short and spreading, with the inner part of 



the wall wanting. 



42. Madrepora pocillifera. 



Madrepora pocillifera, Lamarck, Hist. Anim. sans Verfc. t. ii. p. 280, ed. ii. p. 448 ; Blainville, Manuel 

 d'Actin. p. 390 ; Quoy & Gaimard, Voyage d. I'Astrolabe, Zool. t. iv. p. 236, pi. xix. fig. 5 

 (not 6-10) ; Dana, Zoophytes, p. 484; M.-Edwards & Haime, Coralliaires, t. iii. p. 141 ; Quelch, 

 * Challenger' Reef Corals, p. 155 (non Ehrenberg, Corallenth. d. roth. Meeres, p. 110). 



Madrepora laxa, Quelch (non Lamarck), ' Challenger ' Reef Corals, p. 156. 



The following is a description of the type of Lamarck : — 



Corallum subarborescent ; branches terete, numerously divided : branchlets gradually 

 tapering to a blunt apex. Axial corallites often very large, with a wide aperture and deep cup ; 

 diameter 4 mm., aperture 1"5 to 2 mm., scarcely prominent, wall rounded and porous. Cup 

 with 12 well-developed septa, which gradually taper to the apex, leaving a funnel-shaped aper- 

 ture. Radial corallites all short and subequal, spreading almost at right angles, flattened 

 hemicotyloid in shape, crowded, about 1"5 mm. long and 2 mm. diameter across the lip, 

 becoming shorter and immersed below; lip usually thin and fragile. Star of the radial 

 corallites consisting of 12 septa ; the directives are very prominent, and the second cycle 

 moderately developed. Corallum very porous ; surface reticulate and echinulate ; wall ribbed. 



The ' Challenger ' specimens agree well with the above description, but in some the 

 radial corallites are more irregular in length. 



Var. incrassata. 



The form recorded by Quelch as M. laxa differs only from the above in having the 

 radial corallites with a thickened lip. The apex of the branch is proliferous, but a similar 

 condition occurs in some of the thin-lipped specimens. The thick-lipped form was obtained 



K 



