the identity of the species enumerated, due attention has been paid to the original authorities on which they depend, and, wherever it is possible, a comparison actually made with authentic specimens. In the account which I am now to give of the present collection, I shall confine myself to a slight notice of the remarkable known plants it contains, to characters or short descriptions of the more interesting new species, and to some observations on such of the plants as, though already published, have either bee'n referred to genera to which they appear to me not to belong, or whose characters require essential alteration. In proceeding on this plan, I shall adopt the order followed in the botanical appendix to Captain Tuckey’s Expedition to the River Congo. And as there will seldom be room for remarks on the geographical distribution of the species I have to notice, I shall chiefly endeavour to make my observations respecting them of some interest to systematic botanists. C r u c i f e r .* : . Fifteen species belonging to this family exist in the collection, one of which only appears to be undescribed, and of this the specimens are so imperfect, that its genus cannot with certainty be determined. Of those already published, however, the generic characters of several require material alterations, some of which suggest observations relative to the structure and arrangement of the natural order. S a v ig n y a .R g y p t i a c a , (De Cand. Syst. 2. p. 283,) is the first of these. I t was observed near Bonjem, by Dr. Oudney, whose specimens slightly differ from those which I have received from M. Delile, by whom this plant was discovered near the pyramid of Saqqhrah, and who has well figured and described it in his Flore d’Egypte, under the name of Lunaria parviflora. By this name it is also published by M. Desvaux. Professor Viviani, in giving an account of his Lunaria libyca, a plant which I shall presently have occasion to notice more particularly, has remarked *, that Savignya of De Candolle possesses no characters sufficient to distinguish it as a genus from Lunaria; and still more recently, Professor Sprengel has referred our plant to Farsetiat. The genus Savignya, however, will no doubt be ultimately established, though not on the grounds on which it was originally constituted ; for the umbilical cords certainly adhere to the partition, the silicule, which is never absolutely ses* Florce Libycce Specim. p. 35. t Syst. Vegetab'. 2. p. 871 sile, is distinctly pedicellated in Dr. Qudney’s specimens, the valves are not flat, and the cotyledons are decidedly conduplicate. In describing the cotyledons of his plant as accumbent, M. De Candolle has probably relied on the external characters of the seed, chiefly on its great compression, its broad margin or wing, and on the whole of the radicle being visible through the integuments. It would appear, therefore, that the true character of the cotyledons of Savignya has been overlooked, chiefly from its existing in the greatest possible degree. To include this degree of folding, in which the margins are closely approximated, and the radicle consequently entirely exposed, a definition of conduplicate cotyledons somewhat different from that proposed in the “ Sys- tema Naturale” becomes necessary. I may here also observe, that the terms Pleurorhizae and Notorhizae, employed by M. De Candolle, to express the two principal modifications of cotyledons in Crucifer«, appear to me so far objectionable, as they may seem to imply that in the embryo of this family, the position of the radicle is variable, and that of the cotyledons fixed. I t is at least deserving of notice, that the reverse- of this is the fact; though it is certainly not necessary to change these terms, which are now generally received. On the subject of Savignya, two questions naturally present themselves. In the first place : Is this genus, solely on account of its conduplicate cotyledons, to be removed from Alyssine«, where it has hitherto been placed, to Velleae, its affinity with which has never been suspected, and to whose genera it bears very little external resemblance ? Secondly : In dividing Crucifer« into natural sections, are we, with M. De Candolle, to expect in each of these subdivisions an absolute uniformity in the state of the cotyledons ? As far as relates to the accumbent and flatly incumbent states, at least, I have no hesitation in answering the latter question in the negative; and 1 believe that in one case, namely Hutchinsia, these modifications are not even of generic importance; for it will hardly be proposed to separate H. alpina from petraea, solely on that ground. I carried this opinion farther than I am at present disposed to do, in the second edition of Mr. Aiton’s Hortus Kewensis, where I united in the genus Cakile plants which I then knew to differ from each other, in having accumbent and conduplicate cotyledons; and I included Capsella bursa pastoris in the genus Thlaspi, although I was aware, both from my own observations, and from Schkuhr’s excellent figure *, that its cotyledons were incumbent. I am at * Handb. tab. 180. e e 9
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