122 MADREPORARTIA, 
120. Madrepora selago. 
Madrepora selago, Studer, MB. Akad. Wiss. Berlin, 1878, p. 527, pl.i. fig. 2; Ortmann, Zool. JB, 
1889, Bd. iv. p. 507. 
Corallum pedicellate? Branches extending horizontally, rarely coalescent, 8 to 10 mm. 
thick. The under surface is provided with numerous, somewhat appressed, conical twigs with 
appressed or tubiform corallites; surface covered with rows of delicate echinulations. 
Branchlets on the upper surface arched, tapering, not over 4 cm. long, and only 3 to 4 mm. 
thick ; they arise singly or in groups of two or three from a common base. Axial corallites 
cylindrical, 1 mm., rarely 175 mm. exsert, and 1 to 15 mm. diameter. Radial 
corallites crowded, delicate, and gutter-shaped, rather broader at the apex, with a 
convex margin; they arise at an angle of about 35°; the average length is ] mm., and the 
diameter 1:5 mm. across the lip, those near the apex are a little longer, and the lip gradually 
becomes reduced towards the base of a branchlet; on the main divisions the corallites are 
immersed, excepting on the upper surface of the branches. The star consists of 6 septa, 
which have a breadth equal to about half the radius of the calicle. The corallite-wall is 
fenestrated, the longitudinal striz becoming converted into series of echinulations at the 
base. Studer’s figure 26 does not give a correct representation of the radial corallites ; they 
are not so large as figured, and are not cylindrical but gutter-shaped or spathulate with a 
broader convex apex as already stated. 
A specimen which forms part of the Sayille-Kent Collection appears referable to this 
species, but differs from the type in several respects. It agrees generally with the revised 
description given above, and forms a flat horizontal growth 7°5 cm. thick. The branchlets 
are a little stouter than in the type (5 or 6 mm.), and the main horizontal branches are a little 
confluent so as to form an open reticulum. The radial corallites are immersed or subimmersed 
on all parts excepting the distal 2 or 3 em. of the branchlets, where they are irregular, 
spreading, flattened-labellate, not over 2 mm. long, and usually slightly over 1-5 mm. diameter. 
The axial corallites are 2mm. diameter. The star consists usually of 6 septa, the directives 
being slightly broader than the others; sometimes only the directives are present, in other 
cases, especially in the older corallites, a narrow second cycle may be present. 
A specimen from Ceylon in the Jena Museum has thicker-walled corallites than usual, 
and has been named var. robusta by Ortmann. In this specimen the diameter of the axial 
corallites is 2 to 2°25 mm., not 1 mm. as recorded in Ortmann’s paper. The lip of the radial 
corallites is thin in those situated near the apex of the branchlets, but in those below becomes 
thickened and finally wart-like or immersed. 
Pacific Ocean: New Hanover, Galewo Straits, Great-Barrier Reef, Torres Straits, 
Ceyion. 
a. Flat-top Island, near Marburg. Saville-Kent Coll. 92. 6. 8. 201. 
b, Low Woody Island. Saville-Kent Coll. 92. 6. 8. 315. 
?c. Thursday Island. Saville-Kent Coll. 92. 6, 8. 295. 
