This plant is common in many parts of Mexico, especially on the Irapæan mountains in the neighbourhood of Valladolid, where it was originally discovered and described by Lexarza, that earliest of Orchid-devotees! It was also one of the earliest species of the extensive genus to which it belongs that ever produced flowers in England. The credit of introducing it belongs to the late Mr. Barker, of Birmingham, with whom it bloomed about the year 1839, but it soon disappeared, like nearly the whole of the invaluable collection of Mexican Orchids that I remember having seen in the most splendid condition, shortly after their arrival, in his stoves. Fifteen years afterwards it was reintroduced by M. Linden, from whose establishment the figure in _'Pescatorea'_ was obtained, but it seems to have again been lost. Last spring (1866) I had the pleasure of seeing the species in the best possible health in Mr. Dawson's rich and admirably-managed collection at Meadow Bank near Glasgow, and from his plant, which flowered in April, Mr. Fitch's drawing was prepared. I also received specimens about the same time from Mr. Turner. Still more recently, Messrs. Hugh Low and Co. have imported it in large quantities and excellent condition, and many good varieties have already appeared, though none that I have yet seen are so fine or so richly coloured as that of Mr. Dawson. One that is now flowering at Knypersley is a dull yellowish-green. In its native country it flowers in March, which is about the time of its flowering with us. As to treatment it will naturally be found more at home in the Mexican house, where a cool and comparatively dry atmosphere should be maintained, than in the Peruvian house, which should be suited to the species that are accustomed to a damper and--not unfrequently--still cooler climate. I have no doubt that this distinction will be found of much practical utility, for although "cool treatment" as opposed to "warm" marks a very important division still, just as among "warm" plants it is necessary to separate the East Indian Aerides from the Brazilian Cattleyas, so among "cool" plants it will be advisable to separate the Mexican Lælias from the Peruvian Odontoglossa. Nay, I apprehend that what I call the "Peruvian house" will itself have to be subdivided into two portions, one of which, _i. e._ the warm portion, will contain such plants as the Trichopilias, the Anguloas, and such Odontoglossa as are met with below 6500 feet, while the other or cooler portion will be suited to an innumerable multitude of glorious Orchids that are met with at a still higher elevation. Already cultivators have discovered that _O. Phalænopsis_ and _O. nævium_ cannot be made to thrive in the same house, for though both are "cool" plants the former--coming as it does from a lower level--requires a decidedly warmer climate than the latter, and so it will be in many other cases which are not yet so distinctly understood.