have not the woolly head; and the flowers rise from the fascicles or tufts of spines on the projecting ribs. The Torch-Thistle (_Cereus_) has generally an angular stem with a woody axis, and it has tufts of spines on the projecting angles. It has not a woolly head, and the flowers, which are very large and showy, either arise from the tufts of spines, or from indentations in the angles. The limits of this genus are very uncertain; and several plants which are included in it by some botanists, are placed in other genera by others. The Old-man Cactus was once called _Cereus senilis_, but it is found to have a woolly head of great size, which has very much the appearance of a sable muff, and as, consequently, it cannot belong to that genus, it has been called Pilocereus. This plant is covered with long white hairs, and, when of small size, it looks very much like an old man’s head. In its native country, however, it grows to a great height, and specimens have been imported fifteen feet long, and not more than a foot in circumference. The Peruvian Torch-Thistles (_C. hexagonus_ and _peruvianus_), in their native country, are upwards of forty feet high, though not thicker than a man’s arm. They grow close together without a single branch, and form a singular sort of prickly crest on the summit of some of the mountains in South America. The creeping Cereus (_C. flagelliformis_) has slender cylindrical trailing stems, which hang down on every side when the plant is grown in a pot. The flowers, which are very numerous, are pink. The night-flowering Cereus (_C. grandiflorus_) only opens during the night, and fades before morning; the rays of the calyx are of a bright yellow when open, and the petals are snow-white. The stem is angular, branched, and climbing, throwing out roots at every joint. The common Torch-thistle (_C. speciosissimus_) is an erect plant, with a three or four angled stem, and very large bright crimson flowers, which are purplish inside; and _C. speciosa_, sometimes called _Epiphyllum phylanthoides_, has thin leaf-like stems with beautiful pale rose-coloured flowers. _C. Jenkinsonii_ is a hybrid between the last two species. _C. truncatus_ is another well-known species. Opuntia has stems consisting of round, flat, leaf-like bodies, united together by joints, and generally covered with tufts of spines. The most remarkable species are _O. communis_, the Prickly Pear, grown to a great extent in the South of Europe, and also in Brazil, as hedges, the fruit of which is very good to eat; _O. Tuna_, the Indian Fig, common in South America, and much cultivated there, both as a hedge plant and for its fruit; and _O. cochinillifera_, the Nopal-tree, very much cultivated in Mexico and South America, for the cochineal insect, which feeds upon it. Rhipsalis has slender cylindrical jointed stems, which look like samphire. All these genera have only leaves when quite young, and as soon as the plants begin to grow, the leaves fall off.