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. VII. an almost white colour and formed of a thick mass of succulent tissue, having a sweetish taste. Towards the base of the labellum there is a large cavity, which externally resembles the nectary of an ordinary flower, but apparently never contains nectar. The pointed extremity of the left-hand antenna lies within this cavity, and would infallibly be touched by an insect gnawing the bilobed and basal end of the medial projection of the labellum. The right-hand antenna is turned inwards, with the extreme part bent at right angles and pressed against the column; therefore I do not doubt that it is paralysed as in C. saccatum; but the flowers examined by me had lost almost all their sensitiveness.

Catasetum planiceps (?).—This species does not differ much from the following one, so I will describe it briefly. The green and spotted labellum stands on the upper side of the flower; it is jar-shaped, with a small orifice. The two elongated and roughened antennæ lie coiled up some little way apart and parallel to one another, within the labellum. They are both sensitive to a touch.

Catasetum tridentatum.—The general appearance of this species, which is very different from that of C. saccatum, callosum and tabulare, is represented in fig. 30, with a sepal on each side cut off.

The flower stands with the labellum uppermost, that is, in a reversed position compared with most Orchids. The labellum is helmet-shaped, its distal portion being reduced to three small points. It cannot hold nectar from its position; but the walls are thick, and have, as in the other species, a pleasant nutritious taste. The stigmatic chamber, though functionless as a stigma, is of large size. The summit of the column, and the spike-like anther, are not so much elongated as in