128 MADEEPORAEIA. 



branchlets on the under siirface 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. yS. 

 Under surface almost without branchlets. Branchlets on upper surface very proliferous ; 

 margin of radial corallites oblique, i. 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. «.) 



e. Rocky Island. Saville-Kent Coll. 92. 6. 8. 232. (Var. /3.) 



/. Capricorn Islands. Saville-Kent Coll. 92. 6. 8. 233. (Var. ^.) 



g, h. Capricorn Islands. Saville-Kent Coll. 92. 6. 8. 311 & 312. 



128. Madrepora heljes. 



Madrepora hehes, Dana, Zoophytes, p. 468, pi. 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, Joura. linn. See. Loud. 1886, vol. xxi. p. 19; 

 Quelch, 'Challenger' Reef Corals, p. 155; Rathbun, Proc. U.S. Nat. Mus. 1887, vol. x. p. 16. 



IMadrepora elliptica, Rehberg, Abhand. nat. Ver. Hamburg, 1892, Bd. xii. p. 41, pi. 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 cm. long, scarcely tapering, 

 sometimes much and divaricately divided, apex quite obtuse and sometimes proliferous. 

 Axial corallites 3 to 4 mm. or more in diameter ; wall thick, slightly prominent. Radial 

 corallites equal or subequal, very short and spreading, labellate or gutter-shaped, usually 

 mucb crowded on the branches, their walls sometimes becoming fused together so as to 

 obscure the coenenchyraa; lip 1"5 to 2"5 mm. (rarely 3 mm.) diameter, 1 mm. long, but 

 sometimes a little unequal. Wall slightly thickened, but very fragUe 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 cm. from apex. 

 Apices of branches very proliferous. Axial corallites 5 mm. diameter and 1"5 mm. exsert ; 



