and superum occur; and in one genus of which, namely, Blackwellia, the segments of the perianthium, though the complete number, in relation to the other genera of the order, be present, are all of similar texture and form, and are disposed nearly in a simple series. If the approximation of these three families be admitted, they may be considered as forming a class intermediate between Polypetalæ and Apetalæ, whose principal characters would consist in the segments of the calyx being disposed in a double series, and in the absence of petals; the different orders nearly agreeing with each other in the structure of their seeds, and to a considerable degree in that of the ovarium.
The formation of this class, however, connected on the 440] one hand with Apetalæ by Samydeæ,[1] and on the other, though as it seems to me less intimately, with Polypetalæ by Violeæ, would not accord with any arrangement of natural orders that has yet been given. While the admission of the floral envelope being entirely calyx; and of the affinity of the class with Violeæ, would certainly be unfavorable to M. de Candolle's ingenious hypothesis of petals in all cases being modified stamina.
VIOLEÆ.[2] This order does not appear to me so nearly related to Passifloreæ as M. du Petit Thouars is disposed to consider it; for it not only has a genuine polypetalous corolla, which is hypogynous, but its antheræ differ materially in structure, and its simple calyx is divided to the base. The irregularity both of petals and stamina in the original genera of the order, namely, Viola, Pombalia,[3] and Hybanthus, though characters of considerable importance, are not in all cases connected with such a difference in habit as to prevent their union with certain regular flowered genera, which it has lately been proposed to associate with them.
The collection from Congo contains two plants belonging to the section of Violeæ with regular flowers. One of
