Hemispherical, 7.5 to 12.5 cm. broad and 6 to 10 cm. high: tubercles 12 to 15 mm. long: radial spines 10 to 12, the lower stout, with dusky apex, 12 to 15 mm. long, twice or thrice as long as the whitish setaceous upper ones; central spine (sometimes two) shorter (about 4 mm.), stout, dusky and porrect: flowers 3 cm. long, reddish-white, brownish-red outside: fruit unknown. (Ill. Cact. Mex. Bound. t. 9. figs. 18-20) Type probably lost, as no specimens could be found in the Engelmann Herbarium. Chihuahua, near Cosihuiriachi. So far as can be discovered, this species has not been collected since the original Wislizenus collection of 1846-47. The plants were cultivated by Dr. Engelmann and made to bloom, showing the flowers to be larger and darker colored than in the rest of the group, from which the species also differs in its more robust habit, its very unequal radial spines, and the occasional occurrence of two centrals. ** Central spine hooked. 9.Cactus uncinatus (Zucc) Kuntze, Rev. Gen. Pl. 261 (1591). Mamillaria uncinata Zucc. in Pfeiff. Enum. 34 (1837). Mamillaria bihamata Pfeiff. in Otto and Deitr. Gart. vi. 274 (1840) Mamillaria adunca Scheidw. (1845-1849?). Mamillaria depressa Scheidw. (1845-1849?). Usually globose (occasionally depressed or even subcolumnar), 5 to 6 cm. in diameter (doubtless becoming larger): tubercles 8 to 10 mm. long, woolly in the upper axils: radial spines 4 to 6, rigid, 4 to 6 mm. long, the upper one stouter than the rest and sometimes shorter, reddish-brown and horny, straight or slightly curved, the remainder straight and white with dusky tips; central spine stout and horny, reddish-brown, 7 to 10 mm. long: flowers greenish-white or tinged with red: fruit unknown Type unknown. Entirely Mexican, reported from Chihuahua to Saint Luis Potosi. Specimens examined: San Luis Potosi (Gregg of 1848; Parry 268; Eschanzier of 1891): Chihuahua (Wislizenus of 1846-47; also Chihuahua specimens cultivated in the Jacoby Garden in 1856 and 1857). The variations observed in this species do not seem sufficient for the establishment of varieties. The type form seems to have been globose, with 4 radial spines and a stout central one. The depressed forms with 6 radials and a more slender central represent var. spinosior Lem. (M. depressa Scheidw.); and the subcolumnar forms with 6 radials (the upper one of which is somewhat curved) and a stout strongly hooked central represent var biuncinata Lem. (M. bihamata Pfeiff.) Such combinations of characters, however, do not hold, as any one of the plant body forms may display any one of the spine characters referred to. B. Tubercles terete. * Central spines none: mostly simple globose plants, with very numerous straight whitish setaceous radials. 10. Cactus lasiacanthus (Engelm.) Kuntze, Rev. Gen. Pl. 259 (1891). Mamillaria lasiacantha Engelm. Syn. Cact. 261 (1856).