1853; Trelease of 1892; Nealley of 1892): New Mexico (Wright 311;
Bigelow of 1853, Evans of 1891): Arizona (Pringle of 1881): also
growing in Mo. Bot. Gard. 1893; and in the World's Fair
collection of Mrs. Nickels.

The radial spines are somewhat variable in relative length, often
becoming almost equal, while sometimes the upper radials are very
much reduced. The figure referred to in Cact. Mex. Bound. is not
satisfactory as to the general habit of the plant, which is
flat-topped rather than hemispherical.

6.Cactus heyderi hemisphaericus (Engelm.).

Mamillaria hemisphaerica Engelm. Pl. Lindh. 198 (1850).

Differs in being hemispherical instead of flat-topped, in its
fewer (9 to 12) and shorter (4 to 8 mm.) radial spines, and much
smaller less rough and lighter-colored seeds. (Ill. Cact. Mex.
Bound. t. 9. figs. 15-17) Type, the "Goebel's Garden" plants in
Herb. Mo. Bot. Gard.

Throughout southern Texas and southern New Mexico, and southward;
not extending so far north or west as the species, and apparently
not so abundant within the United States. Fl. May.

Specimens examined: Texas(Schott 322, 614): New Mexico (Evans of
1891): also specimens cultivated in the Goebel Garden, St. Louis,
in 1847, brought from "below Matamoras on the Rio Grande" by the
St. Louis Volunteers, in 1816.