Of the remaining four petals, the two middle are dimidiato-pinnatifid their lateral segments existing only on the upper side; and the two lower are undivided, being reduced to the middle segment or simple lamina. All the petals are erect, and do not cover the stamina in the slightest degree, either in this or in any other stage. The disk is hardly visible. The Anthers are longer than their filaments, of a pale-green colour; those on the upper or posterior side of the flower being manifestly larger, and slightly tinged with brown. The Pistillum is very minute and open at the top. In the next stage, the calyx is no longer imbricate, but open: the petals have their segments in nearly the same relative proportions ; the interior margin of the unguis is just visible; but the transition from unguis to lamina is still imperceptible; the apex of the former not being broader than the base of the latter. It is unnecessary to follow the development through the more advanced stages of the flower, the facts already stated being, in my opinion, absolutely conclusive as to the real nature of the parts in question: and I may remark, that similar observations on certain genera of Caryophyllete, especially Dianthus, Lychnis and Silene, clearly establish the analogy between their petals and those of Reseda. I am aware that it has lately been proposed to include Datisca in Rese- dacese, to which it is nearly similar in the structure of its ovarium, as M. de Jussieu has long since remarked. But this is the only point of resemblance between them; for the calyx of Datisca is certainly adherent, and in most of its other characters it differs widely both from Reseda, and from every other genus yet published. Among the numerous discoveries made by Dr. Horsfield in Java, there is a genus, ( T e t r a m e l e s nob.) however, manifestly related to Datisca, and remarkable in the regular quaternary division of every part of its dioecious flowers. These two genera form an order very different from every other yet established, and which may be named D a t is c e® . C a r y o p h y l l e®. Five species only of this family were collected near Tripoli, none of which are new! Of Z y g o ph y l l e® , six species exist in Dr. Oudney’s herbarium, namely, Tribulus terrestris, found in Bomou; Fagonia cretica, from Tripoli to Benio- leed; Fagonia arabica, at Aghedem j Fagonia Oudneyi nob. with Zygophyllum simplex in Fezzan; and Zygophyllum album every where in the desert. This family, so distinct in habit from Diosmeae or Rutaceae, with which it was formerly united, is not easily characterized by any very obvious or constant peculiarities in its parts of fructification. The distinguishing characters in its vegetation or habit are the leaves being constantly opposite with lateral or intermediate stipulae, being generally compound, and always destitute of the pellucid glands, which universall exist in true Diosmeae, though not in all Rutaceae properly so called. M. Adrien de Jussieu, in his late very excellent Memoir on the great order or class Rutaceae, in distinguishing Zygophylleae from the other subdivisions of that class in which he has included it, depends chiefly on the endo- carp, or inner lamina of the pericarp, not separating from the outer lamina or united epicarp and sarcocarp, and on the texture of the albumen. His first section of Zygophylleae, however, is characterised by the want of albumen; and in his second section I find exceptions to the remaining character, especially in Fagonia Mysorensis, in which the two laminae of the ripe capsule separate as completely as in Diosmeae. Another plant, in my opinion referrible to the same order, and which, in memory of a very meritorious African traveller, I have named Seetzenia africana, has in its ripe capsule the epicarp, or united epicarp and sarcocarp, confined to the dorsal carina of each cell, the endocarp being the only membrane existing on the sides, which are exposed long before the bursting of the fruit. The plant in question has indeed many other peculiarities, some of which may, perhaps, be considered sufficient to authorise its separation from the order to which I have referred i t ; for the aestivation of its calyx is valvular, it has no petals, its five styles are distinct to the base, and the cells of its ovarium appear to me to be monospermous. It completely retains, however, the characters of vegetation on which I chiefly depend in distinguishing Zygophylleai; and I have no doubt of its being Zygophyllum ■ lanatum of Will denow *, by whom it is stated to be a native of Sierra Leone; I suppose, however, on insufficient authority, for the specimens in the Banksian Herbarium, from which I have made my observations, were found in South Africa, near Olifant’s River, by Francis Masson. In all the species of Fagonia, and in the two species of Zygophyllum in Dr. Oudney’s collection, a character in the fructification still remains, which is not found in Diosmeae or Rutaceae, and which, were it general in Zygophylleae, would satisfactorily distinguish this order from all the families it has usually been compared with. This character consists in the direction of the embryo with relation to the insertion of the funiculus, its radicle being seated at the opposite extremity of the seed, or to express, in the unimpregnated ovarium,
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