This is a most charming _Odontoglossum_, allied to the preceding and to _O. phalænopsis_, but perfectly distinct from either. Its bright green narrow leaves--streaked like those of _Saccolabium Blumei_, at once distinguish the plant, even when out of flower, from its fascinating rival _O. vexillarium_; which always bears a glaucous hue, and which has larger and broader foliage, and produces double the number of flowers on a scape. The first rumours that reached us of the plant led to a suspicion that it might, after all, be only a variety of _O. vexillarium_, but these unworthy fears were at once dispelled by the flowering of the plant itself at Mr. Bull's nursery in the early part of last September, when Mr. Fitch prepared his drawing, and Professor Reichenbach obtained materials for the description which appeared in the _Gardeners' Chronicle_ of September 27, 1873. The Professor has also given, in his _Xenia_, a characteristic representation of the wild plant constructed from the specimens supplied to him by its fortunate discoverer, Mr. Roezl; in whose honour the species is very properly named. It is a native of New Grenada, and, like _O. vexillarium_, appears to be exceedingly rare; we must not, therefore, murmur if the precise locality--of which the knowledge is a fortune in itself--should be for awhile withheld. But there would have been no harm in telling us the approximate elevation of the native habitat, as the same is always important as a clue to culture; especially in the case of plants with a limited range. In this instance I apprehend that both _O. Roezlii_ and _O. vexillarium_ are not found at a _very_ high level and that therefore--though happily entitled to rank among "cool" Orchids--they must be placed in the warmer division of the "cool" Orchid-house.