200 MADREPORARIA. 
ADDENDA. 
47 a. Madrepora thurstoni. (Plate XX XV. fig. A.) 
Corallum fastigiate, forming low and broad spreading clumps closely resembling those of 
M. ramiculosa, Dana, which is probably a variety of M. squarrosa, Ehrenberg (see p. 65). 
Colony 48 em. wide and about 18 cm. high, but the base forms a very broad incrustation on a 
massive clump of dead coral, and the total height is 82 em. Main branches nearly 2 cm. 
diameter, not over 10 cm. long; the marginal ones horizontal and often divided into 2 or 3 
branches, which all extend in one plane. On the upper surface of these divisions bi- or trifid 
arched branchlets occur, the distal twigs of which are about 2 cm. long and 4 to 6 mm. thick at 
the base, distinctly tapering. The mode of subdivision of the branches agrees very well with 
Dana’s figure of M. ramiculosa. Axial corallites cylindrical, 2 to 2°5 mm. diameter and about 
1 mm. exsert; wall very porous; margin plane; septa usually 6 in number, subequal, 
moderately developed. Radial corallites small and immersed or subimmersed on all parts 
excepting the distal 1°5 or 2 cm. of the branchlets, where they are nariform, round bursiform, 
or the outer part of the wall may be a little elongate; length 1°5 to 2 mm., diameter 1 mm. 
or a little over; a few which are stouter and more elongate indicate new outgrowths. The 
septa are imperfectly developed, usually only the directives are recognizable in the prominent 
corallites, but in some of those which are immersed the primary cycle may be more complete. 
Corallum porous ; surface reticulate; wall broadly and deeply striate, echinulate towards the 
base. 
Indian Ocean: Ramesvaram. 
a. Ramesvaram. Madras Museum. 88. 11. 25.9. (Type.) 
97. Madrepora surculosa, Dana (p. 104). 
Descriptions of two varieties of this species recorded by Dana were inadvertently omitted 
in the text :— 
Var. turbinata, Dana, Zoophytes, p. 446. 
? Madrepora turbinata, Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 42. 
This variety closely resembles the type in its smaller branchlets; but instead of spreading 
horizontally and forming a solid or reticulate frond, the branches spread obliquely upwards 
and are several inches in length, forming turbinate clumps 12 inches broad and high. Branches 
4 to 2 in. thick ; the smaller branches 1 to 2 in. long, nearly j in. diameter, and often very 
prolific at the summits. The marginal branchlets are as regular as those of the middle, and 
the corallites are not more spreading. (Dana.) 
