MADREPORA. 169 
few smaller branches rise from front and back of trunk and main branches which do not 
conform to the general plane. Secondary branches and branchlets arise somewhat irregularly, 
crowded and strongly divergent above, 7 or 8 mm. diameter, 1:2 to 2 cm. long, rapidly 
tapering to a subacute apex. Axial corallites 2 to 2°5 mm. diameter and of similar length, 
with porous but firm wall, lip rounded, and perforated by a very small aperture. Radial 
corallites very unequal in size and elevation, diverging at an angle of about 45°, tubular, 
somewhat tapering, truncated a little obliquely at summit and rounded ; the wall considerably 
thickened, especially on the outer side, firm but very porous. Length of corallites 0:5 to 
3°7 mm., average about 2°5 mm. ; diameter 0°5 to 1°75 mm., average about 1°5 mm.; dia- 
meter of largest cell 0°38 mm. Septa of axial corallites well developed, 6 primaries meet in the 
centre, others shorter ; the radial corallites have 6 equal, well-developed septa. Coenenchyma 
firm, surface finely echinulate ; wall evenly echinulate, not costate. (Verriil.) 
The specimens which I have referred to this species have the following characters :— 
Corallum laxly arborescent ; branches elongate, 2 cm. thick, scarcely tapering. Sometimes 
the distal 13 cm. of a branch is simple, in other cases the branches bear short stout branchlets 
nearly to the apex. Axial corallites scarcely differing in size from the radial ones, somewhat 
conical, 2°5 to 3 mm. in diameter, with moderately developed primary septa and a rudimentary 
second cycle. Radial corallites dilated, tubular, with much rounded margin and very small 
aperture ; inner part of the wall often incomplete or absent ;. length 2 to 3 mm., diameter 1:5 
to 25 mm.; sometimes adjacent corallites are unequal in length, with a few immersed ones 
between ; primary septa relatively broad, the directives most prominent, second cycle incom- 
plete. Corallum dense, surface and wall closely echinulate. 
The habit of this species would appear to indicate an affinity with EHumadrepora, but the 
form of the corallites and density of the corallite-wall render it necessary to associate it with 
M. valida and allied species. 
Indo-Pacific Ocean : Loo Choo Islands, Korea, Torres Straits, Ramesvaram. 
a, 6. Ramesvaram. Madras Museum. 88. 11. 25. 12 & 93. 4. 7. 152. 
ce. Thursday Island. Saville-Kent Coll. 92.6.8.66. _ 
? d-g. China (probably South). Fisheries Exhibition. 84, 2. 26. 17 to 20. 
?h. Tsu-sima, Straits of Korea. J. F. R. Aylen, Esq. [P.]. 62. 7. 16. 34. 
A: ? —? 93. 4. 7. 169. 
D. Corallum subarborescent or bushy, usually with numerous short proliferations. 
182. Madrepora polymorpha. (Plate XXXI. figs. B to D.) 
Madrepora abrotanoides, Dana (non Lamarck), Zoophytes, p. 477, pl. xli. fig. 1; Verrill, Bull. Mus. 
Comp. Zool. 1864, vol. i. p. 41; ? Studer, MB. Akad. Wiss. Berlin, 1878, p. 539: Rathbun, Bull. 
U.S. Nat. Mus. 1887, vol. x. p. 12. 
Madrepora polymorpha, Brook, Ann. Mag, N. H. 1891, vol. viii. p. 466. 
Corallum fruticose, spreading ramose; branches 8 to 20 em. long, usually about 1:5 to 
2jem. thick, gradually tapering ; the branches bear numerous branchlets, spreading usually 
