25. Cactus halei (Brandegee). Mamillaria halei Brandegee, Proc. Calif. Acad. Sci Scr. 2. ii. 161 (1889). Stems cylindrical, 8 to 10 in a clump, about 30 cm. high and 5 to 7.5 cm. in diameter: tubercles short, with axillary wool: radial spines 10 to 22, rigid and erect-spreading, unequal, 6 to 15 mm. long; central spines numerous and erect-spreading, 1 to 3 of them very stout and prominent (25 to 35 mm. long); all the spines straight, at first reddish-brown, becoming yellowish and ashy, more or less dark-tipped: flowers 2.5 cm. long, bright scarlet (almost throughout): fruit 12 mm, long, clavate and red: seeds black and pitted. (Ill. l. c. t. 6) Type in Herb. Calif. Acad. Abundant on Magdalena and Santa Margarita Islands, western coast of Lower California. Fl. January. Specimens examined: Lower California (Brandegee of 1889, on Magdalena Island). The tubercles are so close together that the plant appears thickly covered with the unusually stout and erect-spreading straight spines, a few of the centrals being specially prominent. The plant is more slender than the ordinary "cylindrical" members of the genus, but stouter than the slender hooked forms of the preceding section. 26. Cactus rhodanthus (Link & Otto) Kuntze, Rev. Gen. Pl. 261 (1891). Mamillaria rhodantha Link & Otto, Icon. t. 26 (1828-31) Mamillaria lanifera Haw. Phil. Mag. lxiii., 41 (), not Salm-Dyck (1850). Oblong or subcylindric, 30 cm. or more high, 7.5 to 10 cm. in diameter, often forking from the middle: tubercles conical, 12 mm. long, 8 mm. in diameter, with woolly axils: radial spines 16 to 20, bristle-like, white, the lower longer (8 to 10 mm.); central spines 6 or 7, rigid, whitish with black tip, 12 mm. long: flowers rose color, 12 mm. in diameter: fruit 2.5 cm. long, cylindrical. (Ill. l. c.) Type unknown. Referred to Mexico in general, but reported as yet from San Luis Potosi to southern Mexico. Fl. profusely all summer. Specimens examined: San Luis Potosi (Bourgeau 47; Pringle 3679; Eschanzier of 1891): also growing in Mo. Bot. Gard. 1893. The specimens of Bourgeau and Pringle have somewhat larger spines than the type, as indicated by the description. 27. Cactus rhodanthus sulphureospinus. Mamillaria sulphurea Forst. Handb. Cact. (1846), not Cactus sulphureus Gill, (1830). Mamillaria rhodantha sulphurea Salm, Hurt. Cact. Dyck. 11 (1850). Central spines sulphur-yellow; otherwise like the species. Type unknown. San Luis Potosi. Specimens examined: San Luis Potosi (Pfeiffer, with no number or date; Eschanzier of 1891). The varietal distinction maintained seems a small one, but it is constant and striking, so far as can be discovered. 28. Cactus capillaris. Mamillaria lanifera Salm, Cact. Hort. Dyck. 98 (1850), not Haw. Cactus laniferus Kuntze, Rev. Gen. Pl. 250 (1891).