42 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
altitude further inland, it is in the parts referred to either prac¬ 
tically at sea level or at most not 50 feet above it; that the 
rainfall is heavy, the average for the year being about 90 inches ; 
that this rainfall is distributed in two wet seasons in the year, 
the one lasting from December to February, and the other from 
April to September; that the temperature ranges from 66 degrees 
to 88 degrees ; that the temperature falls very little during the 
night, and does not vary greatly throughout the year ; and that 
almost the whole country is covered by the densest imaginable 
forest, only broken by the wider rivers and by small patches of 
“ wet savannah,” i.e. grass-covered swamps broken by many 
clumps of trees and by great stretches of an arborescent Aroid 
(Montrichardid), here and there by stretches of white sand reefs, 
also much broken by clumps of small trees, and, though not near 
the coast, by “ dry savannahs,” areas of rocky ground broken by 
coppices. 
Orchids are to be found even at the edge of the sea; indeed, 
two of the best Orchids of Guiana, from the gardener’s point of 
view, are there to be found. 
The sea-coast of Guiana, where it has not been altered by the 
hand of man, is of a somewhat peculiar nature, due to its past 
history. It has been built up by the current from the mouth of 
the Amazon, which runs up in a north-westerly direction, carry¬ 
ing with it much matter from the Amazon and other rivers which 
it passes in its course. Where checked by the current from the 
Orinoko it has to deposit its load. Thus the shore is mainly 
built up of soft alluvial mud, which has been received on its 
arrival from the Amazon, and has been retained by the 
marvellously intricate thicket of mangrove roots quite into which 
the up current runs. Here and there, however, that part of the 
current which strikes on a particular part of the coast has 
brought not mud but sand and broken shell, which it there 
heaps up, and thus forms sandbanks, breaking the otherwise 
uninterrupted line of mangrove growth. Behind such a sand¬ 
bank the mangroves often attain to a considerable size, and 
their trunks are not much obscured by young growth. It is high 
up on trees of this kind, exposed almost to the full blaze of the 
sun, that that most beautiful of all our Orchids, Oncidium 
lanceanum , grows most luxuriantly. It is, however, a widely but 
sparsely distributed species throughout the country. Though it 
