[ 97 ] IV. On several instances of the Anomalous Development of the Raphe in Seeds, and the probable causes of such deviations from the usual course of structure, especially in reference to Stemonurus (Urandra of Tliwaites), tcith some Trefatory Hemarks on that Genus. By John Miebs, Esq., F.B.S., F.Ii.S. 8fc. Read April loth, 185C. In a recent Number of Hooker's Journal of Botany (vol. vii. p. 211), Mr. Thwaites has recorded a new genus, of which he gives the characters under the name of Urandra. This he refers to " OlacacecB, tribe Icacinece.'" I have read over his description with the utmost care, and am obliged to say that I perceive no difference whatever in the cha-racters of Urandra, and those I have detailed of Stemonurus, to which genus he confesses it is closely allied, differing only in all its flowers being fertile, in its small, not pulvinate, stigma, and in the structure of its fruit. The character founded on the constancy of the hermaphi'odite flowers in the plant which he describes, cannot be considered of the smallest generic value, because this circumstance has been shown to exist not only in some species of Stemonurus, but in the contiguotis genus Flatea, in which, althougli some of the plants are imisexual, others are frequently hermaphrodite. I have also shown that the stigma in Stemonurus {Gomphandra, Wall.) is small, and not large and pulvinate as it had been described, but that it becomes subsequently immersed in the epigynous gland which crowns the ovary, a cu'cumstance evidently not observed by Mr. Thwaites ; and that it is tliis gland wliich assumes a pulvinate form on the summit of the fruit, and not the stigma, which may always be seen hidden in a small central depres-sion of the cushion. There remains therefore to be considered only the structure of the fruit ; and Mr. Thwaites's details of the ovary, fruit and seed in Urandra, closely agree with what I have observed in Stemonurus. In this genus, as in all others of the Icacinacece, where the ovule is usually unilocular, the cell is always excentrically placed on one side of the pistil, the point of suspension of the ovules not being from the summit of the cell, but constantly inclined against the side on the line of the displaced axis of the ovary : the lobes of the stigma are always two or fom-, thus showing prima facie that the ovary is normally bilocular, and that the two ovides observed in the cell are reaUy attached, near its summit, to the dissepiment, which, owing to the abortion of the other cell, appears to form the waU of the ovary. I was fortunate enough to meet with the proof of this conclusion in a ripe fruit of the closely allied genus Fennantia, where the ovary is usually unilocular as in Stemonurus; but in the instance alluded to, the fruit was regularly two-celled, and only one seed was perfected in each cell, the remaining abortive ovule being stiU \isible on the dissepiment at the point of attachment of each seed ; this partition was of thin textiire, and the nomishing vessels proceeding from the base formed a longitudinal nerAOU'e in the line of its axis, extending thence to the point of attachment VOL. XXII. O
IV. On several instances of the Anomalous Development of the Raphe in Seeds, and the probable causes of such deviations from the usual course of structure, especially in reference to Stemonurus (Urandra of Thwaites), with some Prefatory Remarks on that Genus.
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