ze. Its usual height is about 5 in., by 4 in. in diameter. The
tubercles are angular at the base, and bear tufts of yellowish spines on
their pointed apices. The flowers are small, and bright rose-coloured,
but only rarely produced on cultivated plants. Introduced from Mexico in
1835.

M. clava (club-shaped); Bot. Mag. 4358.--In the size of its stem, and
the large, brightly-coloured flowers it bears, this species may be
compared with some of the Echinocactuses. The stem is from 1 ft. to 11/2 ft.
high, 4 in. wide at the base, narrowing slightly upwards; the tubercles
are 1 in. long, and nearly as much through at the base, their shape that
of little pyramids, and their tips bear each from eight to eleven stout,
straight spines, pale brown, with a little wool at the base. The flowers
are borne on the top of the stem, two or three of them together; the
sepals are green and red, and the spreading petals are straw-coloured
and glossy, their edges near the top being toothed. In the centre of the
shallow cup formed by the petals, and which measures nearly 4 in. across,
the orange-coloured stamens are clustered, in a kind of disk, through
the middle of which the yellow stigma projects. It is a native of
Mexico, at an altitude of 5000 ft. Introduced in 1848, when it flowered
at Kew, in June, at which time it flowers almost every year now. A warm
greenhouse affords the most suitable conditions for it; but, unless it
is kept in full sunshine both summer and winter, and perfectly dry
during the latter season, it will not produce any flowers. As a
flowering plant, it ranks amongst the very best of the Mamillarias. It
is easily propagated from seeds ripened on cultivated plants.

M. dasyacantha (thick-spined).--Stem 2 in. to 3 in. high, almost
globular, and covered with spiral whorls of tiny tubercles, in the
grooves of which is a little whitish wool, which falls away as the
tubercles ripen. The spines upon the tubercles are arranged in little
stars, with an erect central one. The flowers are small, and spring from
the centre of the stem. This is one of the Thimble Cactuses, and is too
small to have any great attractions, either in stem or flowers. It is,
however, a pretty plant, especially when studded with its ruby-like
flowers, which look like coloured Daisies growing upon a dense tuft of
hairs. It is a native of Mexico, where it grows on high mountains among
short grass and other herbage.

M. discolor (spines two-coloured).--Ste