PSEUDOBULBS _about 3 or 4 inches long, somewhat compressed, ovale, 2-leaved_. LEAVES _sword-shaped, sharp-pointed, a foot or more long, about the same length as the many-flowered nodding_ RACEMES. BRACTS _ovate, acute, scaly_. PEDICELS _equalling in length the average spaces between the_ FLOWERS. SEPALS _and_ PETALS _nearly equal, oblong-lanceolate (the petals sometimes unguiculate), acuminate, of a rich chocolate-brown inside, with edges and tips of a greenish-yellow_. LIP _with a very short claw, fiddle-shaped, at its side-edges plane, its centre-lobe minutely serrate and apiculate, with a multitude of finger-like processes (varying in different individuals) seated on the claw, and with their bristles all more or less inclining forwards. The upper portion of the lip is white, with a brown base, which again is banded with white beneath the series of bristles, which are of a rich golden-yellow_. COLUMN _only one-third the length of the petals, slightly arched, with lacerated, hairy wings nearly concealing the anther_. The vicissitudes which the name of this species has had to undergo within the last three years are full of instruction both to botanists and the public. It was first described by Lindley from wild specimens gathered by Linden in the neighbourhood of Quindiu. Mr. Weir was the next to meet with it, and he succeeded in sending to the Horticultural Society several living plants that had been obtained about 100 miles to the south of Bogotá. He also sent wild specimens in admirable condition which, not agreeing with Lindley's description, and being profusely furnished both at the base of the lip and in the apex of the column with long bristle-like appendages, led to my calling it _O. hystrix_ (_i. e._ the Porcupine Odontoglossum). Messrs. Low also received the plant, through their collector Mr. Blunt, from the same locality as that where Weir met with it, and one of their plants produced flowers which--neither agreeing with Lindley's _O. luteo-purpureum_ nor with my _O. hystrix_--received from Professor Reichenbach the name of _O. radiatum_. Subsequently many specimens flowered, no two of which were alike, though they all maintained a sort of distant family resemblance to _O. luteo-purpureum_ of which--as the Professor himself was the first to point out--there can now be no doubt that they are all varieties. The figure is taken from a plant that flowered in Mr. Day's collection in the autumn of 1865, the flowers of which were twice the size of those of a plant that flowered with me,--but still larger varieties have since appeared in the collections of Lord Egerton of Tatton and Mr. Wentworth Buller. The species, being found at an elevation of 8000 feet or more, requires very "cool" treatment, and should be referred to what--for reasons stated under Plate XX.--I propose to call the "Peruvian house." In this it is very easily grown, and flowers freely.