60 TlMEHRI. 
branches, two or three feet long, was gathered ; and 
in the sand of the bed of the river were found 
large grass-like patches of the little Adder's tongue. 
Ophioglosum macrorhtzon, where it was covered daily 
by the rising water, which is here not free from tidal in- 
fluence. When the river is full the beds are constantly 
submerged. Numerous instances occur of plants, not 
only living, but thriving under conditions so unfavour- 
able to normal vegetation as total submersion, for 
periods more or less long at regularly recurring 
intervals. These are the subjects which brighten 
the shores of the rivers. While they are exposed 
during the dry season, is the time of their activity. 
Presumably while the rains last and the rivers are so full 
that they are constantly covered, they are dormant. The 
phenomenon is remarkable. Several fresh illustrations 
came under my notice on this journey arresting our 
attention. The only satisfactory explanation seems to be 
that as invaders of new domains these plants have, in 
the course of a long succession of years, accommodated 
themselves to the prevailing condition by external change, 
which there is evidence to show has only gradually taken 
place. Orchids were numerous on the overhanging 
branches ; but only two or three kinds were in flower. 
Two specimens of Pleurothallus, not in bloom, clothed 
the more exposed limbs ; in several places the rocks were 
covered in large patches by a species of Ligca which 
just at the time was flowering freely. Seen from a 
distance, it appeared as a sheet of pink, and looked 
exceedingly pretty. The much finer rock plant Mour- 
nera fluviatilis was not found here. All these plants 
