The fact related in the Gardener's Monthly of November, 1881, page 341, of a Cactus flowering usually at night, and by exception in the daytime is very interesting, and it would be of great interest to know the name and origin of this plant. From the given notice it might be Cereus triangularis (Haw.); Cereus compressus (Mill.); Cactus triangularis (Lin.); Cactus triangularis aphyllus (Jacq.); which in our climate usually opens at six o'clock in the evening, and lasts till eleven o'clock the following morning. It has fine white flowers, and broad flat epiphyllum-like leaves. Here it flowers very rarely, and only when of some age, and when permitted to fix its aerial roots in some brick wall. Cereus Napoleonis (Grah.); Cereus triangularis major (Salm. not Pfeiffer's), is very near to this, also with white flowers, but which open in the morning and close in the evening of the same day. If this last was not so very scarce, one could think the described Cactus to be a hybrid between the triangularis and Napoleonis. Like some hybrids of Cereus grandiflorus, the well-known night-blooming Cactus, also, has here a different flowering period.

Referring to my letter of 14th of November last, I can now give a new example of the changing of the flowering time of hybrids of Cactus obtained from the night-blooming sorts. There are several such hybrids already known in collections. Under the name Cereus hybridus spe-ciosus cum grandiflora (Newbert) there is given in the Deutsche Magazin fur garten und Blumen-kunde, Stuttgart, 1881, number 10, page 309-311, description and colored plate of a Cactus obtained from Cereus speciosus crossed with Cereus grandiflorus. It has somewhat the form of the last and much of the color of the first. The flowers of this hybrid open in the evening, and last till the middle of the following day ; it has scarcely any smell. This is a new proof that hybrids between night-blooming and other Cactuses have an intermediate period of flowering.