128 MADREPORARIA. 
branchlets on the under surface are similar to those on the upper, but scarcely so stout, and 
are usually distinctly tapering. The axial corallites are more slender (3 to 3°5 mm.), and 
may sometimes be 4 mm. exsert. Corallum porous, but vitreous ; surface reticulate ; wall 
strongly striate and echinulate. 
Var. a. 
Two small specimens from Rocky Island Reefs appear referable to this species, but 
differ in having thinner-walled corallites and more slender twigs. 
Var. B. 
Under surface almost without branchlets. Branchlets on upper surface very proliferous ; 
margin of radial corallites oblique, 7. e. outer part of wall not so prominent as in type. Wall 
sometimes thin. 
This species approaches the subgenus Tylopora in the form and size of the axial corallites. 
Pacific Ocean: Great-Barrier Reef area. 
a, b. Port Denison. Saville-Kent Coll. 92. 6. 8. 228 & 229. (Types.) 
c,d. Rocky Island. Saville-Kent Coll. 92. 6. 8. 230 & 231. (Var. a.) 
e. Rocky Island. Saville-Kent Coll. 92.6. 8. 232. (Var. @.) 
f. Capricorn Islands. Saville-Kent Coll, 92. 6. 8. 233. (Var. 8.) 
g, h. Capricorn Islands. Saville-Kent Coll. 92. 6. 8. 311 & 312 
128. Madrepora hebes. 
Madrepora hebes, Dana, Zoophytes, p. 468, pl. xxxv. fig. 5; M.-Edwards & Haime, Coralliaires, t. iii. 
p- 142; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 41; Verrill, Proc. Essex Inst. 1865, 
vol. v. p. 20; ibid. 1869, vol. vi. p. 100; Duncan, Journ. Linn. Soc. Lond. 1886, vol. xxi. p. 19; 
Quelch, ‘Challenger’ Reef Corals, p. 155; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. p. 16. 
? Madrepora elliptica, Rehberg, Abhand. nat. Ver. Hamburg, 1892, Bd. xii. p. 41, pl. iv. fig. 10. 
Corallum fruticose or stunted arborescent, laxly divided, with stout spreading branches. 
Branches terete or subterete, 12 mm. thick, usually not over 7:5 em. long, scarcely tapering, 
sometimes much and divaricately divided, apex quite obtuse and sometimes proliferous. 
Axial corallites 3 to 4mm. or more in diameter; wall thick, slightly prominent. Radial 
corallites equal or subequal, very short and spreading, labellate or gutter-shaped, usually 
much crowded on the branches, their walls sometimes becoming fused together so as to 
obscure the coenenchyma; lip 1°5 to 2°5 mm. (rarely 3 mm.) diameter, 1 mm. long, but 
sometimes a little unequal. Wall slightly thickened, but very fragile and porous, strongly 
striate. Septa well developed in the axial corallites ; in the radial ones not destined to form 
buds the star is scarcely recognizable. Corallum porous ; surface reticulate and echinulate. 
Var. labiosa. 
Branches sometimes 1°8 cm. diameter at a point not more than 3 em. from apex. 
Apices of branches very proliferous, Axial corallites 5 mm. diameter and 1°5 mm. exsert ; 
