PSEUDOBULBS _from 3 to 5 inches long, ovate, subcompressed, furrowed, 2-leaved_. LEAVES _sword-shaped, obtuse, or obtusely-acute, sometimes slightly oblique at their extremities, a foot or more long, shorter than the many-flowered flower-stems_. FLOWER-STEMS _loosely branched, 2 to 3 feet long, rather drooping, bearing from 20 to (sometimes) 100_ FLOWERS. BRACTS _from half an inch to an inch long, sharp-pointed, clipping tightly hold of the stem_. SEPALS _and_ PETALS _nearly equal, oblong-linear, acute, plane at the edges, usually about an inch long, light green, transversely banded with brown_. LIP _with a fiddle-shaped, apiculate limb doubled back on its unguis or claw, white, changing into purple at its base, where it is sometimes very obscurely bidentate_. WINGS _of_ COLUMN _crisp at the edges, plane at the base_. This is not one of the most attractive species, but its stately appearance, the profuseness with which its flowers are produced and their pleasant aroma, will secure it a place in most collections. It is common in Guatemala, where Mr. Skinner originally discovered it, and it probably extends as far as Mexico, where the nearly allied species (_O. Reichenheimii_), figured in the preceding Plate, is found. As it is only met with at a great elevation, it must be treated as a very "cool" Orchid, under which _régime_ it will flower abundantly in the spring months. The chief danger to be guarded against is that of its exhausting itself--like many species of _Phalænopsis_--by over-much flowering, and to prevent which it is of course only necessary to break off some of the scapes. DISSECTIONS.--1. Lip, seen in front; 2. Lip and column, seen sideways: _magnified_. Plate XVII [Illustration: Odontoglossum atropurpureum.] PLATE XVII. ODONTOGLOSSUM LUTEO-PURPUREUM. YELLOW AND BROWN ODONTOGLOSSUM. O. (EUODONTOGLOSSUM) pseudobulbis ovatis subcompressis diphyllis, foliis ensiformibus racemis multifloris nutantibus subæqualibus, bracteis ovatis acutis squamæformibus, pedicellis internodiis æquantibus, sepalis petalisque subæqualibus oblongo-lanceolatis acuminatis, labelli breviter unguiculati lateribus planis, limbo subpanduriformi antice lacero-serrulato, cristâ ad basin multidigitatâ, columnæ petalis triplo brevioris vix arcuatæ alis multifidis crinitis. ODONTOGLOSSUM LUTEO-PURPUREUM, _Lindl. Orch. Linden._ _n._ 85; _Fol. Orch._ _n._ 7. ODONTOGLOSSUM RADIATUM, _Rchb. Gard. Chron._ (1864, _New Plants_, _n._ 307.) ODONTOGLOSSOM HYSTRIX, _Bateman in Gard. Chron._ 1864, _New Plants_, _n._ 282. Habitat in N. GRANADA, prope Quindiu, alt. 8000 p., _Linden_; prope Santa Fé de Bogotá, _Weir_, _Blunt_. DESCRIPTION.