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.