Madrepora in the British Museutn. 463 



rous give rise to the short ramiculi already referred to. 

 Ininicrscd corallites are ])ractically absent. Wall thin but 

 firm, star of six septa more or less fully developed, the lower 

 directive often much broader than the others. Corallum very 

 dense ; surface dense, smooth, and almost void of corallites on 

 the underside, slightly rough, but not spinose on the anterior 

 surface of the stouter branches. The wall of the apical and 

 younger lateral corallites is roughly costulate, and the stria- 

 tions are continued on to the coenenchyma, but below the 

 striations are lost on the corallites as well as on the general 

 surface. 



South Seas. 



Ma'Jrepora intermedia. 



Corallum arborescent, similar to that of M. hrachiata in 

 habit. Main branches 2 to 2'5 centim. thick and 25 centim. 

 long, moderately subdivided, especially near the apex ; ulti- 

 mate divisions 3 to 6 centim. long and 1 centim. or more 

 thick, gradually tapering to a blunt apex or more rapidly 

 tapering and pointed. Apical corallites 2"0 millim. diameter, 

 0'5 to 2 millim. exsert, but usually short ; aperture large, 

 frequently oval ; primary septa well developed, secon- 

 dary series not prominent. Lateral corallites tubular, 

 spreading, very variable in length and also in diameter. 

 The majority extend almost at right angles to the branch, 

 excepting near the apex, and have a more or less oblique 

 aperture ; they are about 3 millim. long and 2 millim. 

 diameter ; wall firm, but not thickened. Numerous short 

 tubular to subimmersed corallites occur between the others, 

 varying from 1 to To millim. in diameter. The corallites 

 become short and thickened, wart-like on the main branches, 

 whilst on the under surface the majority are immersed. 

 Primary septa all narrow, but the directives are the more 

 prominent, and in the older parts of the corallum may be 

 broad. Corallum very porous, surface reticulate and echinu- 

 late ; wall striato-echinulate, becoming later echinulate in 

 linear series. 



Maldive Islands. 



Madrepora leptocyathus. 



Corallum flattened, vasiform from a broad base, not pedi- 

 cellate. Marginal branches oblique, fused into a solid plate 

 below, excepting near the periphery, where they are a little 

 flattened and covered with short, crowded, appressed, tubular 

 corallites with thin wall. On the upper surface all the 

 branchlets rise from a solid base with very numerous im- 

 mersed corallites. The branchlets are about 3 centim. long 



32* 



