Depressed-globose, 3 cm. in diameter, simple: tubercles broader
at base, 6 to 8 mm. long, with naked axils: spines all pubescent;
radials 15 to 20, with dusky tips, the lateral 10 to 12 mm. long,
the lower weaker, shorter and curved, the upper shorter; solitary
central spine reddish, slender, somewhat twisted, usually hooked
upwards, 15 to 25 mm. long: flowers red (?): fruit reddish (?),
ovate, about 10 mm, long: seeds reddish, oblique-obovate, 1.2 mm.
long, pitted, with subventral hilum. Type in Herb. Coulter.
San Luis Potosi.
Specimens examined: San Luis Potosi (Eschanzier of 1891).
Resembles C. grahami, but with fewer and more slender pubescent
spines, longer and less rigid central, more exserted fruit, and
much larger reddish and strongly pitted seeds with subventral
hilum.