stems are more like some of the Mamillarias than the Cereuses.  The flowers are developed near the top of the stem, two or three opening together; they are composed of a tube 2 in. long, clothed with long spines and large, green, scaly sepals below, the latter gradually enlarging till at the top they become as large as the petals, which are 2 in. long, with a spread of nearly 3 in., rounded at the tips, and coloured deep blood-red, tinged with orange inside.  The stamens are clustered together sheaf-like, with the dark green stigmas protruding through them.  This is a native of New Mexico, whence it was introduced in 1883, and flowered in May.  Mr. Loder, of Northampton, has successfully cultivated it in a cool frame in the open air, and it has also grown well in the Kew collection when treated in a similar way.  This suggests its hardiness and fitness for window cultivation.  Owing to the watery nature of the stems, it is necessary that they should be kept quite dry during the winter.

C. pentalophus (five-winged); Bot.  Mag. 3651.—­As the name denotes, the stem of this erect-growing, somewhat slender species has five very prominent sharp-edged ridges, along which are little clusters of small spines about 1/2 in. apart; the stem is 1 in. in diameter, and the angles are wavy.  The flowers are about 3 in. wide, spreading, the petals, broad and overlapping, rose-coloured, except in the centre of the flower, where they become almost pure white; the anthers are yellow, whilst the colour of the rayed stigma is purplish-blue.  A native of Mexico, introduced and flowered in 1838.  For its cultivation, the temperature of a warm greenhouse is required, though during summer it may be placed in a sunny position in a frame out of doors.  If grown in windows, it should be kept through the winter in a room where there is a fire constantly.

C. peruvianus (Peruvian).—­A tall-grower, the stems fleshy when young, and very spiny.  The ridges on the stem number from five to eight, with stellate bundles, about 1 in. apart, of small, stiff black spines.  The flowers appear upon the upper portion of the stem, and are 5 in. across, the petals pure white above, tinged with red below, and forming a large saucer, in the middle of which the numerous stamens, with yellow anthers, are arranged in a crown.  There is something incongruous in the tall, spine-clothed, pole-like stem, upon which large, beautiful, water-lily-like flowers are developed, looking quite out of place on such a plant.  Flowers in spring and early summer.  It requires warm greenhouse or stove treatment.  There are some fine examples of this species at Kew.  A variety of this species, with a fasciated or monstrous habit, is sometimes cultivated.  Introduced in 1830.