72 MADREPORARIA. 
little tortuous, 12 mm. thick below; branchlets often 5 cm. long and 4 to 8 mm. thick, 
acuminate and subacute; surface of the corallum scabrous, not at all striate. Axial 
corallite 1:5 mm. long and broad; radial corallites obsolete below 7:5 em. from the apex ; 
above short, round, nariform, rather distant and fragile; star obsolescent, the directive septa 
but slightly prominent. (Dana.) 
The Ponapé specimen referred by Ortmann to this species is 16 cm. high and 24 cm. 
broad; branches 8 em. long and 1 em. thick, slowly tapering, often bent; apices much 
divided. Axial corallites 2 mm. diameter or slightly over, 1 to 2 mm. exsert, but provided 
with very small buds to near the margin; wall firm, aperture large. Radial corallites im- 
mersed below, then very short, and finally, nearer the apex, nariform or tubo-nariform, 
unequal in size. A few are proliferous, but scarcely longer than the others; the longest 
measure 4.mm., and are often a little compressed, 1°2 to 1:5 mm. in diameter; surface 
spongy, vermiculate, and echinulate ; wall finely striato-echmulate. The outer part of the 
wall is often slightly thickened ; and small, thin, or tubular corallites, turned in various 
directions, are scattered between the others to near the apex. 
The species appears very close to M. implicata ; and Dana’s descriptions are insufficient 
for their proper separation. M. tortuosa has stouter branches, more prominent corallites, 
and a number of small ones opening in various directions. Dana states that the surface 
of the ceenenchyma is not striate in the type specimen; it is distinctly vermiculate in the 
Ponapé specimen recorded by Ortmann. 
Pacifie Ocean: Fiji Islands, Ponapé (Caroline Islands). 
57. Madrepora implicata. 
Madrepora implicaza, Dana, Zoophytes, p. 466, pl. xxxvil. fig. 2; M.-Edwards & Haime, Coralliaires, 
t. ji. p. 144; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 41; Rathbun, Proc. U.S. Nat. Mus. 
1887, vol. x. p. 19. 
Corallum 15 to 20 cm. high, cespitoso-arborescent, closely ramose ; branches crowded, 
curved, and tortuously entangled, often coalescing, slenderly attenuate; stems 8 mm. thick, 
branches 4mm. Corallum scabrous and striated, with linear pores. Axial corallite 1-6 mm. 
in diameter. Radial corallites obsolete below 5 cm. from the summit; above this short, 
round, nariform or fragile, scattered ; star obsolescent. (Dana.) 
This species may prove to be a slender variety of M. tortuosa. 
Pacific Ocean : Fiji Islands. 
58. Madrepora pruinosa. (Plate XXXIV. fig. B.) 
Corallum cespito-arborescent, about 12 cm. high and 17 em. wide ; branches 1 em. thick, 
7 to 9 cm. long, usually much divided. Axial corallites 2°75 mm. diameter, usually 2 mm. 
exsert ; wall rather thin. Radial corallites immersed or subimmersed on the main divisions 
and up to within 4 em. of the summit, or at most with a few verruciform corallites ; more 
distally the corallites are round, nariform or tubiform, about 2 mm. diameter and | to 2-5 mm. 
