Epiphytal. _Pseudobulbs_ oblong obtuse, compressed, sulcate, two inches long, of a dull brownish green, each bearing one leaf from the apex. _Leaves_ lanceolate acute, leathery, eight to ten inches long. _Scape_ radical, bearing a many-flowered panicle. _Flowers_ large, numerous, very showy, measuring about two and a half inches in both directions, handsomely marked; _sepals_ obovate, recurved, about an inch long, deep chestnut brown, with indistinct transverse bands and marginal indications of yellow, the lateral ones connate; _petals_ larger, about an inch and a half long, and an inch and a quarter wide, roundish-obovate, the margin undulate, the base suddenly narrowed into a claw, the central parts wholly deep glossy chestnut-red, the edge for about a quarter of an inch in width yellow, closely marked by short irregular transverse bars of chestnut-red; _lip_ with a longish narrow claw, and large transversely reniform deeply bilobed front segment, an inch and three fourths broad, which is coloured like the petals, the claw spotted with yellow and red, crested, the crests usually consisting of five rugged equidistant warts, the two middle of which are sometimes wanting. _Column_ with small angulate wings, banded with lines of violet. Oncidium Forbesii, _Hooker_, _Botanical Magazine_, t. 3705; _Lindley_, _Folia Orchidacea_, art. _Oncidium_, No. 60; _Williams_, _Orchid Grower’s Manual_, 5 ed., 254. The genus _Oncidium_ is a very large one, and there are many species well known in cultivation, but the one we now illustrate belongs to a section in which there are few that are so distinct in colour. The flowers are not so large as in _O. crispum_, of which there are many distinct varieties, differing in size and colour—variations which often depend on the vigour of the plants. The same may be said of _O. Forbesii_, the stronger the bulbs the finer the blossoms. Our sketch was taken from a well-grown plant in the collection of E. Bonny, Esq., Downs Park Road, Hackney, who is forming a choice collection of Orchids. _Oncidium Forbesii_ is an evergreen species, with pseudobulbs of a greenish brown colour; the foliage is of a dark green, and the flowers are chestnut-brown, with the sepals and petals irregularly margined with bright lemon-yellow. It blooms at different times of the year, and lasts for several weeks in perfection. We find the plants do well in small pans or baskets, and also on blocks of wood. When grown in pans or baskets we have found them grow freely in good fibrous peat, with pieces of charcoal on the top of the peat, as they like to work their roots in among the charcoal, and should have plenty of drainage, and but very little peat earth. When cultivated on blocks they require more water in the growing than in the resting season.