confirms this conclusion. Besides, every character in the
original description of C. radians applies exactly to these
Mexican plants and to our Texan specimens as well. Aside from
the fact that the Mexican specimens are apt to be more robust, I
can discover no difference whatever. For discussion of
relationships see under C. scolymoides.

46. Cactus radians pectenoides, var. nov.

Differs in its cespitose habit, fewer (16 or 17) and stouter
spines (8 to 9 mm. long), and its larger and longer (10 mm.) less
deeply grooved tubercles. Type in Herb. Coulter.

San Luis Potosi.

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

47. Cactus corniferus (DC.) Kuntze, Rev. Gen Pl. 260 (1891).

Mamillaria cornifera DC. Rev. Cact. 111 (1829).
Mamillaria impexicoma Lem. Hort. Monov. Cult. 5 (1839).
Mamillaria cornifera impexicoma Salm. Cact. Hort. Dyck.
20 (1850).

Globose, 7.5 cm. in diameter, simple: tubercles oblong-ovate, 2
cm long, crowded, the younger axils woolly: radial spines 15 to
26, rigid and horny, curved or sometimes straight, reflexed,
bulbous at base, yellowish (whiter with age) and with dark tips,
very sharp, 10 to 12 mm, long; the central one much stouter,
darker, slightly deflexed, 12 to 16 mm long, sometimes wanting: