ON THE AMAZON. ; 241 
up as the water recedes. The shores of the large rivers produce 
scarcely any of these; their waters beat on the sand with too much 
violence to allow of such frail things existing there; but by the small 
inland lakes connected with the Tapajoz, and near the creeks at the 
mouth of some of the igarapés, minute leafless Ufricularias, Eriocaulons, 
Alismas, &c., cover the white sand in thousands. A Utricularia, which 
you will find under No. 1050 (U. uniflora, MS.), is surely the simplest 
in its structure of all its family. Stems of the size of an ordinary 
sewing-needle, fixed into the sand by a small cone of radicles, without 
leaves, but with a minute tubular 2-lipped bract a little below the 
flower, which is white and comparatively large, complete the description 
of its outward aspect. I have often been struck with the wonderful 
contrast in size which is presented here in both the animal and vegetable 
world. Under a gigantic Castanheira, or a Caryocar, may occasionally 
be seen an almost microscopic Cyperacea ; and the same lake which 
produces this fairy Utricularia, bears on its bosom the queen of the 
waters, Victoria regia. Another Utricularia (Coll. no. 1053, U. quin- 
queradiata, MS.) has a peculiarity of structure to me quite novel, 
though you may have met with it before. It is a small species, with 
submerged stems and bladdery leaves, but the pedicels, which are about 
two inches long, have about midway a large horizontal involucre of five 
rays, resembling the spokes of a wheel. This floats on the water, and 
supports the upper part of the pedicel in an erect position ; the whole 
recalling a sort of floating lamp I have seen, especially as the large 
yellow flower may be considered to represent the flame. The rays are 
half an inch long, clavate, not hollow, but composed of about six series 
of large diaphanous cellules. The cellules are convex on the surface, 
giving the rays a papillose appearance, hexagonal, pale green, with pink 
interstices. The rays are trifid at the extremity; segments short, twice 
dichotomous, the last divisions capillary, rarely sacciferous. 
I said above that the Amazon and Tapajoz have scarcely any of these 
fugitive plants ; but on the shore of the former, a little below Santarem, 
I have been delighted to meet with a couple of Podostemacee, growing on 
scattered stones. This is almost the only place where as yet I have 
seen stones by the Amazon; but as I ascend higher, I hope to meet 
more frequently with localities suitable for this i interesting tribe of 
plants. The few igarapés which run into the rivers near Sanjarem 
have all either gravelly or muddy bottoms: it is true that decayed 
