These are characterised by a thin, drooping or trailing stem, and, though not strictly climbers, they may most fittingly be considered in a group by themselves.  Some botanists have made a separate genus for them, viz., Cleistocactus, but for all practical purposes they may be grouped under the above heading, whilst popularly they are known as the Rat’s-tail or Whipcord Cactuses.  Two of them—­viz., C. flagelliformis and C. Mallisoni—­are generally grafted on the stem of some erect, slender Cereus or Pereskia, or they may be worked on to the stem of a climbing Cereus, such as C. triangularis, in such a way as to hang from the roof of a house.  A large specimen of C. flagelliformis, growing from the climbing stem of C. rostratus, was, for a long time, conspicuous among the Cactuses at Kew, but owing to the decay of the “stock” plant, this fine specimen no longer exists.  A large Pereskia, trained along the roof in the Cactus-house at Kew, has recently been grafted with a number of pieces of C. flagelliformis, which in a few years will, no doubt, form a handsome specimen.  In the same establishment a specimen of C. Mallisoni is grafted on the stem of another kind, and is very attractive when in flower.  C. serpentinus thrives well upon its own roots.  For the cultivation of this little group, the instructions given for the climbing and other kinds may be followed.

C. flagelliformis (whip-formed).—­Stems prostrate, or, when grafted on a tall stem, pendent, 1/2 in. in diameter, round, with numerous ridges almost hidden by the many clusters of fine bristle-like hairs.  Flowers 2 in. long and 1 in. wide; colour bright rosy-red.  In some parts of Germany this plant is one of the commonest of window ornaments, and it is so well grown by the peasants there, that the whole window space is completely screened by the numerous long, tail-like stems, 4 ft. or 6 ft. long, which hang from baskets.  It is sometimes cultivated by cottagers in England, and we have seen a very fine specimen in a cottager’s window in Gunnersbury.  Without its pretty bright-coloured flowers, this Cactus has the charm of novelty in the form and habit of its stems, and as it is easily cultivated in a window through which the sun shines during most of the day, it is just the plant to grow for the double purpose of a screen and a curiosity.  If planted in baskets, it should be potted in a porous loamy soil, and kept moist in the summer and perfectly dry in winter.  Summer.  Peru.  Introduced 1690.

C. Mallisoni ( Mallison’s); Bot.  Mag. 3822.—­This is supposed to be of hybrid origin, a Mr. Mallison having sent it to Dr. Lindley to be named, and stating that he obtained it by fertilising flowers of C. speciosissimus with pollen from C. flagelliformis.  Whatever its origin, it is a distinct kind, with stems similar to those of the last-named, but thicker and slightly less spiny, and flowers 4 in. long by 4 in. across the spreading petals, the whole being bright red with