Globose (?), 5 cm. in diameter: tubercles short-conical, about 6
mm. long, with very woolly axils: radial spines 18 to 20,
setaceous-bristly and radiant, 5 to 8 m in. long; central spines
5 to 7 (usually 6), stout and horny, more or less recurved,
spreading, 20 to 25 mm. long; all straw-colored, but the centrals
darker: flowers deep red (darker, even brownish, outside), 8 to
10 mm. long: fruit unknown. Type, Pringle of 1891 in Herb. Gray.

San Luis Potosi.

Specimens examined: San Luis Potosi (Pringle of 1891).

Evidently a member of the Chrysacantha group and near C.
rhodanthus sulphureospinus, but differs in the much shorter
tubercles, straw-colored spines, shorter radials, much longer
centrals, and smaller darker flowers.

33. Cactus sphaerotrichus (Lem.) Kuntze, Rev. Gen. Pl. 261
(1891).

Mamillaria sphaerotricha Lem. Cact. 33 (1839).

Depressed-globose: tubercles cylindrical, obtuse, with some
axillary bristles: radial spines very much crowded, exceedingly
numerous, radiant, very slender and bristle-like, white; central
spines 6 to 10 and even more, erect and more rigid: flowers pale
reddish: fruit unknown. Type unknown.

Referred to Mexico in general, but reported only from San Luis
Potosi.