sepals, 5 petals, 10 to 15 stamens, 3 stigmas): fruit 8 to 12 mm.
long: seeds 1.5 mm. long, black and shining. (Ill. Cact. Mex.
Bound. t. 1 and 2. figs. 1-4) Type, the specimens of Wright in
Herb. Mo. Bot. Gard.

On naked mountain tops and sides, extreme southwestern Texas (Val
Verde County to El Paso) and southward into Coahuila and
Chihuahua.

Specimens examined: Texas (Wright 227 of 1849, also of 1852;
Nealley of 1892): Coahuila (Bigelow of 1853): Chihuahua (Pringle
212): also growing in Mo. Bot. Gard. 1893.

The plants densely covered above with delicate ashy-gray spines
and with naked tuberculate base are readily recognized. It still
remains an open question whether the flowers are developed from
the axils of tubercles of the same season or the last ones of the
preceding season. Dr. Engelmann inclined to the latter view, as
all the other characters of the plant associate it with the
"lateral-flowered" species; and in the absence of definite
observation we have retained it there. If the nearly central
flowers indicate that they are produced from growth of the same
season the species would seem to be allied to Coryphantha, in
which group its small flowers and small tubercles would be
anomalous.

13. Cactus micromeris greggii (Engelm.).

Mamillaria micromeris greggii Engelm. Syn. Cact. 261 (1856).