a shallow cup, 2 in. across;
anthers forming a compact sheaf in the centre. Flowers in summer. This
distinct and very pretty species was introduced many years ago from
Mexico, where it was discovered in 1845 by a Mr. Potts, to whose love
for these plants we are indebted for a great many choice kinds collected
and sent to England by him. It grows naturally in a red, sandy loam, and
under cultivation requires warm-house treatment, except during the
autumn, when it may be placed in a frame and exposed to full sunshine
and plenty of air.

M. Schelhasii (Schelhas').--A pretty little tufted kind, its habit and
size being shown in Fig. 69. The stem produces offsets freely at the
base, which grow into full-sized stems, and develop young ones, till a
compact cushion is formed. Tubercles closely arranged, cylindrical,
shining green, with fifteen to twenty radial, white, hair-like spines,
1/2 in. long, and three inner ones, which are thicker, purplish in colour,
usually only one being hooked. Flowers white, with a line of rose down
the middle of each petal, 3/4 in. across. Flowering season, beginning of
summer. Native of Mexico. It may be grown out of doors in a sunny
position in summer, and wintered on a shelf in a greenhouse.

[Illustration: FIG. 69. MAMILLARIA SCHELHASII.]

M. Schiedeana (Schiede's).--Stem globose, 3 in. to 5 in. high, thickly
clothed with long, narrow, pointed tubercles, the bases of which are set
in white wool, whilst the apices are crowned with tiny stars of white
silky spines; more like the pappus of a Composite than the spines
usually found on Cactuses. A healthy plant has a very pretty and silky
appearance which cannot well be described. The flowers are small and
unattractive; they are succeeded by the red fruits, which remain on the
plant a long time, and add to its beauty. Native country, Mexico.
Introduced 1838. Should be grown in a greenhouse where frost is
excluded, and where there is plenty of sunlight at all times. It is
easily increased, either from seeds or by means of the offsets developed
at the base of old stems.

M. semperviva (ever-living); Fig. 70.--Stem pear-shaped, 3 in. wide, the
top slightly depressed. Tubercles conical, 1/4 in. long, their bases set in
a cushion of white wool, their tips bearing tiny tufts of wool, and four
small spines, which fall away on the tubercles becoming ripe, leaving
two short, diverging, central spines. Flowers small, not ornamental, and
scantily develope