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192 of so forcible an ejection no doubt is to drive the soft and viscid cushion of the disc against the hairy thorax of the large hymenopterous insects which frequent the flowers. When once attached to an insect, assuredly no force which the insect could exert would remove the disc and pedicel; but the caudicles are ruptured without much difficulty, and thus the balls of pollen might readily be left on the adhesive stigma of the female flower.

Catasetum callosum.—The flowers of this species are smaller than those of the last, but resemble them in most respects. The edge of the labellum is covered with papillæ; the cavity in the middle is small, and behind it there is an elongated anvil-like projection,—facts which I mention from the resemblance in some of these points between the labellum of this species and that of Myanthus barbatus, the hermaphrodite form of Catasetum tridentatum, presently to be described. When either antenna is touched, the pollinium is ejected with much force. The yellow-coloured pedicel is much bowed, and is joined by a hinge to the extremely viscid disc. The two antennæ stand symmetrically on each side of the anvil-like projection, with their tips lying within the small cavity of the labellum. The walls of this cavity have a pleasant nutritious taste. The antennæ are remarkable, from their whole surface being roughened with papillæ. The plant is a male, and the female form is at present unknown.

Catasetum tabulare.—This species belongs to the same type as C. saccatum, but differs greatly from it in appearance. The central portion of the labellum consists of a narrow, elongated, table-like projection, of