226 MR. S. O. RIDLEY ON THE CORALLIIDyG. [Feb. 7, 



several smaller angular tubercles which point outwards ; size '053 to 

 •058 mm. long by -OSo mm. broad (including the tubercles); shaft, 

 excluding tubercles, about "02 mm. broad. 



Hah. Mauritius, 75 fathoms. 



This species is based on a single dry specimen very finely preserved, 

 obtained recently by the British Museum from a collector in Mauri- 

 tius, Mr. V. De Robillard, together with some remarkably fine 

 specimens of species of Gorgoniidce. Its chief larger measurements 

 are : — Main diameter of common stem ' 1 1 mm. ; largest branch — 

 antero-posterior diameter at base 10 mm., lateral diameter 7 mm. ; 

 at 50 mm. from origin the same diameters are 7 mm. and 5 mm. 

 respectively. Maximum transverse breadth of the whole corallum 

 135 mm., maximum height 105 mm. 



The species differs from all to which names have been hitherto 

 assigned in the elaborateness and peculiarities of its method of 

 branching, with the exception of a specimen which was assigned by 

 Dr. Gray (P. Z. S. 1867, p. 126) to his Hemicorallium johnsoni, 

 and which then belonged to the Liverpool Free Museum. This 

 specimen, differing as it does from the typical example of that 

 species in the collection of the British Museum in its slender and 

 strongly arborescent habit, appears to me to be entirely distinct from 

 Dr. Gray's species, a fact which is apparently meant to be indicated 

 by his subsequent statement (Cat. Lithophytes, p. 24) that the 

 so-called animal of his figure is a fleshy Alcyonoid parasitic on a 

 stony coral. 



The present species agrees in the mode of branching in one plane 

 with C. secundum, Dana (U.S. Expl. Exped., Zoophytes (vii.), p. 641, 

 |)1. Ix. fig. 1), and also in the fact that many of the polypes are 

 borne on small lateral branchlets ; but differs from it (judging by 

 the description) in having polypes on the posterior as well as the 

 anterior surface, as also in the very pale pinkish colour of the cortex 

 (that of G. secundum being scarlet), and the pure white of the hard axis 

 (that of G. secundum being white and red). The small points which 

 project from the cortex in the lines of Dana's strise are, perhaps, 

 represented by the small dots represented in Dana's enlarged figure 

 of a polype with adjacent cortex ; but these may just as well he pits 

 as dots, according to the figure. Nothing is known of the spicules 

 of C. secundum ; but, as we have seen above, that species must be 

 referred to the genus Pleurocorallium. Those of C. stylasteroides 

 differ from those of the white variety of C. nobile only in their 

 size, which is about one third less than that of the latter ; but the 

 excavations for the verrucse (Plate IX. fig. 3), and the thinness of 

 the cortex, are amply sufficient to prevent its being confounded with 

 that form. The apparent anastomosis between some of the branches 

 is due to fracture and subsequent adherence of the broken pieces 

 to the remainder of the corallum, the reunited pieces having 

 apparently contrived to live. 



With regard to the axial tubes of 1 mm. diameter, alluded to in 

 my diagnosis in uncertainty as to their import, they may possibly 

 ^ Broken off from the actual base. 



