MADEEPOEA. 179 



" Height of the largest specimen 13 inches ; diameter of trunk at base r5 ; diameter of 

 lateral cells "08. 



"This species branches somewhat like M. carduus and M. rosaria, Dana, but the 

 corallites are entirely different in form." ( Verrill.) 



? Ousima, Japan. 



b. Radial corallites which do not become converted into axial ones are more or less nariform 



and have the margin distinctly rounded. 



193. Hadrepora rosaria. 



Madrepora rosaria, Dana, Zoophytes, p. 465, pi. xxxvi. fig. 3 ; M.-Edwards & Haime, CoralliaireB, t. iii. 

 p. 138 ; Quelch, ' Challenger ' Eeef Corals, p. 162 ; Eathbun, Proc. U.S. Nat. Mus. 1887, vol. i. 

 p. 18 ; Ortmann, Zool. JB. 1888, Bd. iii. p. 150. 



Corallum erect, arborescent, 38 cm. high and 10 cm. wide ; stem closely subdivided and 

 covered throughout with crowded ramiculi, which are very obtuse, 6 to 8 mm. thick, even at 

 the apex, subterete, often proliferous. Axial corallites 2 to 3 mm. broad, a little exsert. 

 Radial corallites stout and compressed-nariform, with a very thick margin, striate and 

 sometimes subseriate, many are proliferous ; star 12-rayed, distinct. {Dana.) 



The specimens in the collection which apper to be referable to this species are numerous 

 and exhibit considerable variation in habit and in the size of the corallites ; they fall into 

 three well-marked groups, the first with two varieties : — 



A. Forma rosaria. 



Stem simple or a little subdivided, or several stems may arise from the same base, which 

 almost invariably consists of dead coral. Branchlets very crowded, varying from simple 

 tapering branchlets 2'5 cm. long and 7 mm. thick to much and spreadingly divided ones 

 3 to 5 cm. long and 7 to 10 mm. thick ; they arise at an angle of about 45°, but as their 

 subdivisions are chiefly on the outer side, the terminal twigs appear at right angles to the 

 stem. The whole corallum has a bottle-brush appearance and varies from 7 to 10 cm. in 

 diameter. Axial corallites 2"5 to 3 mm. broad and 1 to 5 mm. exsert, but usually not over 

 2 mm. ; wall thick and firm, margin plane or rounded .: septa in two cycles, the primaries 

 well developed. Radial corallites thick-walled, nariform or tubular, a little compressed or 

 quite round, varying in different specimens; diameter 2 mm., length varying from sub- 

 immersed to 3 mm. or more, the longer ones are proliferous. Usually at a point about 1 cm. 

 from the apex of a twig the corallites become less prominent, and on the stem and stouter 

 subdivisions they are all immersed; the star consists of 12 septa, the directives very broad, 

 the others quite narrow. Corallum very dense, surface and wall finely and closely echinulate. 

 The Ponape specimens have rather smaller corallites on the apical divisions and the lateral 

 ones are usually distinctly compressed. 



