MADKBPOKA. 165 



175. Madrepora concinna. (Plate XVII.) 



Madrepora concinna. Brook, Ann. Mag. N. H. 1891, vol. viii. p. 460. 



Corallum corymbose, 30 cm. broad and 12 cm. high, from a central base, scarcely pedi- 

 cellate. Under surface of the branches horizontal, much flattened, more or less confluent, 

 9 cm. long and 2 cm. broad, provided with irregular verruciform and lateral, elongate, tubular, 

 or conical corallites ; immersed ones almost absent. Branches on the upper surface 5 to 6 cm. 

 long, 8 to 13 mm. thick, very proliferous. Axial corallites 3'5 mm. diameter at the base, 

 tapering, 3 mm. exsert. Radial corallites very unequal ; those at the apex are very short, 

 small, and thin- walled ; others immediately below are tubo-naiiform or tubular, with a round 

 or oblique aperture, frequently opening inwards ; some are 3 to 6 mm. long and 2 to 3 mm. 

 in diameter, spreading, but not at right angles ; wall thick, margin rounded ; others between 

 are shorter or subimmersed ; all are short or subimmersed at the base of the branches. Star 

 not prominent, consisting of narrow directive septa and 4 others, which are rudimentary. 

 Corallum dense ; surface and wall finely echinulate. 



Indian Ocean : Mauritius and Amirante Islands. 



a, b. Mauritius. Purchased. 78. 2. 4. 3 & 8. (Types.) 



c. Etoile Island, Amirante Islands. H.M.S. ' Alert.' 93. 4. 7. 160. 



d. ? ? 93.4.7.156. 



176. Madrepora loripes. (Plate VIII. fig. B.) 



Madrepora loripes. Brook, Ann. Mag. N. H. 1892, vol. x. p. 459. 



Corallum bushy, much divided, with numerous short, stout, arched branchlets, usually 

 devoid of corallites on the inner side. Base incrusting, without corallites ; main branches 

 about 14 cm. long and 1"6 cm. thick at the base, laxly divided, each division crowdedly covered 

 with unequal branchlets, which consist of an elongate and thickened tubular corallite, which 

 bears buds laterally and on the outer surface, but not on the inner, excepting on the distal 

 part of those which are over 2 cm. long ; length 8 mm. to 4'5 cm., diameter 4*5 to 8 mm. 

 Axial corallites 4 mm. diameter, a little less on the smaller twigs ; wall thick, but very porous, 

 margin rounded ; star well-developed, but deep, occasionally in very large corallites (5 mm.) 

 a third cycle of septa is present. Radial corallites on the distal 3 cm. of the stouter divisions 

 appressed tubo-nariform to spreading tubular, the angle varying with the size of the coralhte 

 and the condition of the inner part of the wall, the smaller ones are 4 mm. long and 1"15 mm. 

 diameter, and cylindrical, often with one or two small bursiform buds ; a few similar small 

 corallites also occur between the prominent ones ; wall moderately thick and margin slightly 

 rounded, more distinctly so in proliferous corallites. The inner part of the wall is thin at 

 first, but with increase in length becomes as thick as in the other parts. On the lower 

 portions of the branches the majority of the corallites are scattered irregularly, thin-walled, 

 and subimmersed to verruciform and appressed tubiform, with short blunt twigs at intervals 



z 



