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Show 224 MR. S. O. RIDLEY ON THE CORALLIID^E. [Feb. 7, opera-glasses, or of two short globose bottles united by their sides consists of two globose masses, often somewhat flattened at distal end, separated by a more or less deep constriction, their surface microtuberculate; to the proximal extremity of each is attached a short handle-like process, of variable shape, bearing several long tubercles, and about one third the length of the larger lobes ; average maximum size *053 m m . long by '053 m m . across the two lobes; thickness of lobes, antero-posteriorly, about *044 m m. The thickness of the cortex appears to be correlated with the smoothness of the hard axis in the stem (higher up this is distinctly striated) ; for in the other species of Hemicorallium, H. secundum, the thinner cortex appears to be associated with a striated stem. The explanation (physiological) appears to be that the ccenosarcal canals, which would have grooved the surface of the axis, find sufficient protection in the cortex when this is thick. Turning to G. (Pleurocorallium, Gray) secundum, Dana (U.S. Expl. Exp., Zoophytes, vol. vii. p. 641, Atlas, Zooph. pl. Ix. fig. 1), we find again the mode of branching to be substantially that in one plane; here too the polypes are said to be confined to tbe front or sides of the branches, but to be borne mostly on small branchlets or pinnae scattered over the edges and front of the main branches-an arrangement differing from that of both the preceding forms, but agreeing with that to be described below in the new species C. stylas-teroides, with which this species further agrees in the growth in one plane. Unfortunately the spicular characters are unknown ; but, from resemblances which have been found to exist between this and a form described below as a variety of it and agreeing in all generi-cally important characters with Hemicor allium johnsoni, I have little doubt of its similar generic identity with that species : therefore one of the genera Pleurocorallium and Hemicorallium must give way, and the former must stand, having precedence in description. Hemicorallium therefore = Pleurocorallium ; and Hemicorallium johnsoni = Pleurocorallium johnsoni. Looking at the relations of C. nobile to the species described below as new under the name of C. stylasteroides, we find a thin cortex in both, a low polype-verruca, and a spicule differing only in size; and it is only in those characters which, as I have stated, I believe to be less essential in the classification of this Order, viz. mode of branching, colour, and form of axis (i. e. cylindrical or oblong in section), that we find great differences ; and the first two of these have been already seen to vary widely in C rubrum, and in their variation to approximate that species to C stylasteroides. No other recent species has been described. The only other species with which I am acquainted are the fossil forms C.pallidum, Michelin (Iconogr. Zoophytol. p. 16, pl. xv. fig. 9 ) } from the Miocene of Italy and Tertiaries of Scinde, and C. beckii, M.-Edw. and Haime (Distr. meth. polyp, palaeoz. p. 188), from the White Chalk of Faxbe. The former is distinguished from our species by having the method of branching of C. nobile, viz. cylindrical branches given off at considerable intervals ; and it appears to |