Madrepora in the British Museum. 405 



outer wall a little convex, 1"5 to 2*5 millira. long and nearly 

 2 niillim. diameter. On the stouter ramiculi two or three 

 corallites become 3 millim. long and bear three or four buds. 

 The ramiculi are as numerous on the inferior (posterior) sur- 

 face of the_ branches as elsewhere, but are usually shorter. 

 Star usually indistinct, but one or both directive septa mode- 

 rately prominent. Corallum moderately porous, surface 

 spongy, echinulate ; wall striato-reticulate and echinulate. 



The species is allied to M. gravida, Dana. 



Darnley Island (/. B. Jukes). 



Madrepora pacijica. 



- ^Madrepora robusta, Bassett-Smith (non Dana), Ann. & Mag. Nat. Hist, 

 vol. vi. 1890, p. 452. 



Corallum subarborescent, stout, spreading obliquely, resem- 

 bling that of M. nohilis in habit. Branchlets 6 to 15 centim. 

 long and 2 to 3 centim. thick, simple or subsimple, tapering 

 slightly to a blunt apex, or the distal half more rapidly tapering 

 and pointed. Apical corallites 2*5 millim. diameter or a little 

 over, 2 millim. exsert. Lateral corallites very much crowded, 

 about half are elongate, tubular, half-tubular, or dimidiate, 

 the remainder short, labellate, snbimniersed, or immersed. 

 The prominent corallites are about 1*5 millim. in diameter 

 and 3 to 4 millim. long, spreading nearly at right angles, 

 often a little recurved ; wall firm but relatively thin, delicately 

 striate without echinulations. Primary cycle of sepia 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. 



A specimen referred by 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 incrustatioa 

 over dead pieces of coral. 



Pacitic Ocean ; Samoa Islands ; China Sea. 



Madrepora (Isopora) plicata. 



Corallum consisting of broad oblique plates from a common 

 base. The plates are about 8 centim. long and 4 to 9 centim. 

 broad near the apex, narrower below and 1 centim. thick. 

 Each plate bears one or more prominent longitudinal ridges 

 on its surface. Each ridge bears a number of rosettes of 

 corallites, the centre corallite in each being rather larger than 

 the others, thus indicating an approach to branch formation 

 with its accompanying enlarged terminal (parent) corallite. 

 Corallites at the apices of the plates tubular, 2 millim. in 



