122 MADEEPOEARIA. 



120. Madrepora selago. 



Madrepore selago, Studer, MB. Akad. Wiss. Berlin, 1878, p. 527, pi. 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 corallitesj 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 1'5 mm. exsert, and 1 to 1'5 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 1 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 striae becoming converted into series of echinulations at the 

 base. Studer's figure 2 b 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 Saville-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 cm. 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 2 mm. 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. lu 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. 



*. Low Woody Island. Saville-Kent Coll. 92. 6. 8. 315. 



? c. Thursday Island. Saville-Kent Coll. 92. 6. 8. 295. 



