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 

 {Montr ichar diet), 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 



