ty plant, resembling M. Grahami
in all points except the seed, which, as is denoted by the name, is half
enveloped in a corky covering, suggesting acorns. Stems simple,
sometimes proliferous at the base, globose when young, afterwards almost
cylinder or pear-shaped, 5 in. high, 2 in. in diameter; tubercles 1/2 in.
long, arranged in twelve spiral rows, slightly woolly in axils. Spines
radiating, in two rows, about fifty on each tubercle, the three or four
central ones being hooked at the tips or sometimes straight; length,
1/2 in. to 11/2 in. Flowers (only seen in the dried state) 1 in. long and wide.
Native of the dry gravelly hills and sand ridges in California and
Colorado, and, therefore, requiring greenhouse treatment. This plant is
cultivated in the Kew collection, but it has not been known to flower
there. It is one of the most ornamental of the very spinous species, the
radial spines being almost white, whilst the central ones are black, and
look like tiny fish-hooks. A large proportion of these Mamillarias are
far more interesting in the form and arrangement of their tubercles and
spines than in any floral character, and it is on this account that so
many which are insignificant as flowering plants are included here.

M. pulchra (handsome).--Stem globose when young and cylindrical when
old, flattened at the top; height from 4 in. to 6 in.; tubercles large,
egg-shaped, arranged in from eleven to thirteen spiral rows; spines in
compact tufts, their bases set in whitish wool, irregular in length, and
almost covering the whole of the stem. Flowers medium in size, developed
near the top of the stem from the woolly axils of the tubercles; colour
bright rose. Native of Mexico. Flowering season, June. Introduced in
1826. A rare kind nowadays, though one of the prettiest. It should
always be grown in a warm house. It has been also called M. pulcherrima.

M. pusilla (small).--A tiny tufted plant, belonging to the group known
as Thimble Cactuses. It has stems 2 in. high; short, dark green
tubercles, with tufts of whitish wool in the axils; spines thin and
bristle-like, twisted, nearly 1 in. long, almost hiding the stem; they
are whitish, with black tips. The flowers are yellowish-white, with
streaks of red. Common in Mexico. Flowering season, May. It should be
grown in a frame in summer, and wintered on a shelf in a warm
greenhouse. It would, no doubt, thrive in a window if kept in a sunny
position and placed under a glass