OCR Text |
Show 226 MR. S. O. RIDLEY ON THE CORALLIID^. [Feb. 7, several smaller angular tubercles which point outwards ; size *053 •058 m m . long by -035 m m . broad (including the tubercles); shaft, excluding tubercles, about *02 m m . broad. Hab. 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 Mauritius, Mr. V. De Robillard, together with some remarkably fine specimens of species of Gorgoniida. Its chief larger measurements are:-Main diameter of common stem1 11 mm.; largest branch- antero-posterior diameter at base 10 mm., lateral diameter 7 m m . ; at 50 m m . from origin the same diameters are 7 m m . and 5 m m. respectively. Maximum transverse breadth of the whole corallum 135 mm., maximum height 105 m m. 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. 64 I, pl. 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 d secundum being scarlet), and the pure white of the hard axis (that of C. secundum being white and red). The small points which project from the cortex in the lines of Dana's striae are, perhaps, represented by the small dots represented in Dana's enlarged figure ol a polype with adjacent cortex; but these may just as well be pits as dots, according to the figure. Nothing is known of the spicules of O. 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 verruca? (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 m m . diameter, alluded to in my diagnosis in uncertainty as to their import, they may possibly 1 Broken off from the actual base. |