444 Mr. B. Clwke on Relative Position ; -\m\\\A MMWVU'iKI fully made out, these three last may form a small group inter-mediate between the Sertularians and the Campanularians. I have sent a specimen of Reticularia to the British Museum. EXPLANATION OF PLATE XVI. A. Fig. 1. Coppinia arcta. Two full-grown polyps and polyp-ceUs; another forming between them. Fig. 2. Reticularia immersa investing a polyp-cell of Sertularia abietina. Fig. 3. Portion of the crust still more enlarged. XLIII. — Observations on Relative Position ; including a new Arrangement of Phanerogamous Plants. By B. Clarke, F.L.S. &c. [Continued from p. 200.] [With three Plates.] Part III. On the Structure of Ovaries consisting of a Single Carpel ; to which is added a Table of the Position of the Carpels in Dicar-pous Ovaries. With reference to the position of the single carpel, the most obvious mark has been taken as a guide to the placenta or ventral suture, such as the origin of the style from one side of the ovary, the parietal attachment of the ovules ; and when from being erect, or pendulous from the apex of the ovary, they failed to answer this pm*pose, the existence of a furrow or fissure on one side only of the style, such as occurs in Amygdalese, has been adduced as an evidence. But that the peculiarities of structure from which its position is in certain cases inferred may be better understood, the following notes are subjoined, accom-panied in some instances with remarks on affinities and other details, the Natural Orders being consecutively arranged as in Tables I. and II. Endogens. PoNTEDERACEiE. The ovary of Pontedera lanceolata is re-markable for agreeing with that of Centranthus ruber in two of the three cells being much reduced in size and barren, and the raphe of the single pendulous ovule is lateral also in both, that of Pontedera being more strongly marked than usual. Of the three carpels of Pontedera, two are obliquely posterior and one anterior, the latter only being fertile. Marantace^e. Of the three carpels of Maranta dichotoma, two are obliquely posterior and one anterior, with but little va-riation. Of these, two are barren and their cavities suppressed; but in this instance either of the three carpels is indifferently the 1
BioStor
