Globose, 5 to 10 cm. in diameter, simple: tubercles cylindrical, slender, 12 to 14 mm. long, with woolly axils: radial spines about 13, 5 to 8 mm. long, lower ones longer and stouter, especially the lateral ones pectinate; the central shorter, straight, and robust: flowers small, yellowish-red: fruit unknown. Type in Herb. Mo. Bot. Gard. Among rocks, from San Ignacio to Mission San Fernando, Lower California, and "perhaps farther north in the interior." Specimens examined: Lower California (W. M. Gabb 19 of 1867). 35. Cactus sphaericus (Dietr.) Kuntze, Rev. Gen Pl. 261 (1891). Mamillaria sphaerica Dietr. Allg. Gart. Zeit xxi. 94 (1853). Obovate or clavate, 5 cm. or more high, proliferous and at length densely cespitose: tubercles elongated-ovate, acutish, 12 to 10 mm. long with axillary wool: radial spines 12 to 14, setaceous, 7 to 9 mm. long, bulbous at base, straight or curved, white; central spine straight, subulate, somewhat shorter, but scarcely stouter: flowers yellow, 3.5 to 5 cm. long: fruit unknown. Type unknown. Sandy ridges in the valley of the Rio Grande (both sides of the river), from the mouth to Eagle Pass. Fl. from March throughout the season. Specimens examined: Texas (Schott of 1852): also specimens cultivated in St. Louis in 1845 and 1861. Dietrich's description was taken from plants collected by Poselger at Corpus Christi. The Schott specimens are from Eagle Pass. Dr. Engelmann calls attention to the fact that this species approaches Coryphantha in its exserted ovary and large flower, but the flowers are clearly from the growth of the preceding season. The species is said to be too near the Mexican C. longimamma of central and southern Mexico, but in the absence of type specimens of either the question can not be settled. The usual characterization of C. longimamma is as follows, which seems to make it distinct enough: 36. Cactus longimamma (DC.) Kuntze, Rev. Gen. Pl. 260 (1891). Mamillaria longimamma DC. Rev. Cact. 113 (1829). Ovate or at length cylindrical, simple or cespitose: tubercles oblong-ovate, large at base, 4 to 5 cm. long: radial spines 7 or 8, radiant and equal, 8 to 10 mm. long or more, more or less pubescent; central spines 1 to 3, somewhat longer and spreading: flower 4 cm. long, becoming 6 cm. broad when fully expanded, yellow. (Ill. DC. Mem. Cact. t. 5.) II. CORYPHANTHA. Flowers from the base of a groove on young or nascent tubercles (hence appearing terminal), mostly large: spines never hooked (except in the doubtful C. brunneus). * Flowers yellow. + The originally central flowers pushed aside by the continuous development of new tubercles: usually a single prominent central spine. 37. Cactus missouriensis (Sweet) Kuntze, Rev. Gen. Pl. 259 (1891).