little teat; in allusion to the tubercles.)

Something over 300 different kinds of Mamillaria are known, but only a
small proportion of these may be considered as garden plants. They are
characterised generally by short, symmetrically-formed stems, sometimes
aggregated together and forming a dense tuft, but, as a rule, each plant
has only one stem. The generic name is descriptive of the chief feature
in these stems, namely, the closely-set, spirally-arranged tubercles or
mamillae, which vary considerably in the different kinds, but are always
present in some form or other. Some kinds have stems only 1 in. high by
2/3 in. in diameter, and the tubercles hidden from view by the
star-shaped cushions of reddish or white spines. In some, the spines are
erect and hair-like, giving the plant the appearance of tiny
sea-urchins; another group has the principal spines hooked at the tip,
and the points in these so sharp that if the hand comes in contact with
them they hook into it and stick like fish-hooks. The purpose of these
hooked spines seems doubtful; certainly, they cannot serve as any
protection to the plant itself, as they are so strong that the plant
must be torn up by the roots before the hooks will give way.

The spines in M. macromeris are straight, and measure 2 in. in length; in
M. multiceps they are in two series, the one fine, white, and short, the
other yellow and stout. The most marked section of this genus, however,
is that represented by M. fissurata (Fig. 61), in which the tubercles
are large, spreading horizontally, and angular, resembling most closely
the foliage and habit of some of the Haworthias. No one who had not read
up the botany of Mamillarias would suspect that this plant belonged to
them, or even to the Cactus order at all. There is a good specimen of it
in the Kew collection. When in flower the family resemblance is easily
seen; but as this species does not flower freely, it will be known by
its remarkable foliage-like tubercles, rather than as a flowering
Cactus. And the same remark applies to many of the Mamillarias; their
stems thickly beset with tubercles and spines, always regular in
arrangement, and neat and attractive in appearance.

The following remarks made by Dr. Lindley when describing M. tenuis,
give a good idea of the singular, yet pretty, stems of some of these
plants: "Gentle reader, hast thou never seen in a display of fireworks a
crowd of wheels all in motion at once, crossing