CACTUS (fig. I), the genus of melon-thistle or Turk's cap cactuses, contains about i8 species, which are found in the West Indies, Mexico, Venezuela and Colombia. The typical species, Cactus melocactus, of Jamaica, forms a succulent mass of ovoid form, from I to aft. high, the surface divided into numerous furrows like the ribs of a melon, with projecting angles, which are set with a regular series of stellated spines—each bundle consist ing of about five larger spines, accompanied by smaller but sharp bristles—and the top of the plant being surmounted by a cylin drical crown 3 to Sin. high, composed of reddish-brown, needle like bristles, closely packed with cottony wool. At the summit of this crown the small rosy-pink flowers are produced, half pro truding from the mass of wool, and these are succeeded by small red or pink, elongated berries. These plants usually grow in rocky places with little or no earth to support them. The fruit of this and related species, which has an agreeably acid flavour, is eaten in the West Indies. The group is distinguished by the distinct cephalium or crown which bears the flowers. Disocactus, a related genus, consists of about 7 species native to Brazil and Paraguay.