(1848).
Mamillaria strobiliformis Muhlenpf. Allg. Gart. Zeit. xvi. 19
(1848), not Scheer (1850).
Mamillaria calcarata Engelm. Pl. Lindh. 195 (1850).
Cactus calcaratus Kuntze, Rev. Gen. Pl. 259 (1891).

Differs in its smaller size; proliferous and much more cespitose
habit, the dilated base of the more spreading tubercles, fewer (8
to 12) radial spines, usually a single central spine (wanting in
young plants) and somewhat larger flowers. (Ill. Cact. Mex.
Bound. t. 74. fig. 1, seeds) Type, Lindheimer of 1844 in Herb.
Mo. Bot. Gard.

Texas, from the Brazos to the Nueces.

Specimens examined: Texas (Lindheimer of 1844; Fendler 34; Wright
of 1850, 1854, 1857): also specimens cultivated in St. Louis in
1845, 1848, 1853, 1859.

This seems to represent the northeastern extension of the
species, and doubtless it will be found merging into it south and
west of the Nueces. Curiously enough one of the prominent
distinctions originally given was the single central spine, while
in the type specimen there occur tubercles with more than one
central.

50. Cactus echinus (Engelm.) Kuntze, Rev. Gen. Pl. 260 (1891).

Mamillaria echinus Engelm. Syn. Cact. 267 (1856).