4. Tetrandria. Trophis, Batis, and Hippophae, t. 425, are good examples of this, though Mr. Viborg is recorded by Schreber to have occasionally found united flowers intermixed with the barren ones in the last-mentioned genus. If this be usual, Hippophae must be removed to Polygamia Dioecia. The rest of the Order appear to have the accessory parts alike in both flowers, as Viscum, t. 1470.
5. Pentandria. Humulus, t. 427, is almost the only certain instance here. Spinacia, Acnida and Cannabis would be unexceptionable, but they are less absolutely dioecious, being sometimes monoecious; see p. 331. The rest of the Order is at best doubtful; nor can the pretended amentum of the barren-flowered Pistacia entitle it to a permanent place in this Class, for its fructification is truly a panicle. Clutia, more properly Cluytia, may possibly remain here. It has no business in the Order Gynandria.
6. Hexandria. No difference of structure is