MADEEPOEA.. 39 



A specimen in the collection of the British Museum, which I doubtfully refer to this 

 species, differs from typical M. nobilis and M. pacifica in habit, but agrees closely with the 

 above description. It is erect arborescent, about 35 cm. high, laxly branched, the branches 

 about 2'5 cm. diameter near the base, and up to 25 cm. long, with crowded corallites on the 

 superior surface, and thicker appressed, more distant, and very irregular ones below. Axial 

 corallites 3 mm. diameter and 2 mm. or more exsert, with a large, often oval, aperture, and 

 12 well-developed septa. The tubular corallites are about 1'5 ram. diameter, usually 

 compressed, and 2"5 to 5 mm. long. Corallum very firm, but moderately porous, surface 

 spongy-echinulate ; wall subcostulate, strongly echinulate near the base. The corallites are 

 more irregularly crowded and not so spreading as those of M. pacifica, the wall is echinulate 

 and the corallum more porous. The directive septa are thick and moderately broad ; the 

 others thin and narrow, often quite rudimentary. 



Pacific Ocean : Kingsmill Islands. 



a. ? ? 93. 4. 7. 81. 



15. Madrepora pacifica. (Plate XXX. fig. B.) 



Madrepora robusta, B.-Smith (non Dana), Ann. Mag. N. H. 1890, vol. vi. p. 452. 

 Madrepora pacifica, Brook, Ann. Mag. N. H. 1891, vol. viii. p. 465. 



Corallum subarborescent, stout, spreading obliquely, resembling that of M. nobilis in 

 habit. Branchlets 6 to 15 cm. long and 2 to 3 cm. thick, simple or subsimple, tapering 

 slightly to a blunt apex, or the distal half more rapidly tapering and pointed. Axial coral- 

 lites 2'5 mm. diameter or a little over, 2 mm. exsert. Radial corallites much crowded, about 

 half are elongate, tubular, half-tubular, or dimidiate, the remainder short, labellate, sub- 

 immersed or immersed. The prominent corallites are about 1"5 mm. in diameter and 3 to 4 

 mm. long, spreading nearly at right angles, often a little recurved ; wall firm, but relatively 

 thin, delicately striate, without echinulations. Primary cycle of septa not prominent, the 

 directives most noticeable ; in many of the immersed corallites they alone can be made out. 

 Corallum very dense, surface spongy-echinulate ; in many parts the corallites are so crowded 

 that little or no coenenchyma occurs between them. 



Tbe species differs from M. nobilis in the more crowded and more elongate corallites, 

 without the thickened wall which occurs in the larger corallites of that species ; also in the 

 more rudimentary septa and the denser corallum. 



A specimen referred by Mr. Bassett-Smith to M. robusta appears to belong to this 

 species, but the branches are not so stout as in the type, and the corallum appears to form an 

 incrustation over dead pieces of coral. 



Pacific Ocean : Samoa Islands, China Sea. 



a. Samoa Islands. Rev. S. J. Whitmee [P.]. 75.10.2.13. (Type.) 



b. Tizard Bank, 5 fath. H.M.S. ' Rambler.' 89. 9. 24. 107. (=i»/. robusta, B.-Smith.) 



o2 



