developed together on a little stem, when they have the appearance of being much too large for so small a plant to support.  The pale green of the stem and its brown spines contrast prettily with the handsome yellow flowers, which are brightened by the streaks of red on the petals and the clear red colour of the stigma.  It is a native of Mexico, and was introduced about 1840, flowering early in summer.  It requires a warm greenhouse temperature all the year round, with, of course, plenty of sunshine.  It may be grafted on the stem of an erect-growing Cereus, such as C. serpentinus or C. Napoleonis, the stock to be not higher than 6 in., and about as wide as the plant of E. concinnus is at the base.

[Illustration:  Fig. 29.—­Echinocactus concinnus.]

E. coptonogonus (wavy-ribbed); Fig. 30.—­Stem globose, seldom more than 5 in. in diameter, depressed on the top, with from ten to fourteen strong, sharp-edged, wavy ribs, the furrows also being wavy.  Spine tufts set in little depressions along the margins of the ribs, five spines in each tuft, the two upper 1 in. long and four-angled, the two lower flattened and shorter, the fifth, which is the longest, being placed in the top of the cushion.  Flowers 2 in. across, daisy-like, produced in April and May; tube very short; sepals and petals linear, spreading, white, with a purple stripe down the centre; stamens red, with yellow anthers; pistil purple, with an eight-rayed, yellow stigma.  A native of Mexico. (Syn.  E. interruptus.)

[Illustration:  Fig. 30.—­Echinocactus coptonogonus.]

E. cornigerus (horn-bearing).—­This remarkable plant, of which a portion is represented at Fig. 31, has the stoutest spines of all cultivated Cactuses, and their arrangement on the ridges of the stem is such as would withstand the attacks of all enemies.  The broad tongue-like spine is purple in colour, and as strong as iron; the three erect horn-like spines yellow, and as firm as the horns of an antelope, to which they bear a resemblance.  The stem is sphere-shaped, grey-green in colour, and is divided into from fourteen to twenty-one stout wavy ribs, upon which the spine tufts occur at intervals of about 2 in.  The arrangement of the spines is shown in the illustration, as also is the position of the flowers, which are small, with narrow purple petals and brown-red sepals.  The plant is a native of Mexico and Guatemala, and would require stove treatment.  We have seen only small living examples, but according to descriptions and figures, the most interesting character it possesses is its spiny armament.  It has been called Melocactus latispinus and Echinocactus latispinus.

[Illustration:  Fig. 31.—­Echinocactus cornigerus.]