BY J. H. MAIDEN AND E. BETCHE. 375 



digitate leaflets, like a four-leaved clover or like Oxalis. The 

 fact is, as clearly pointed out and proved in A. Braun's paper 

 before mentioned, that the four apparently digitate leaflets are 

 really two pairs of leaflets, one pair above the other, with a short 

 rhachis between them, though the very short rhachis disappears 

 sometimes entirely in the swollen top of the leafstalk of floating 

 leaves, and is in air-leaves nearly always indistinct, twisted and 

 often concealed by hairs. The pinnate arrangement of the leaflets 

 can be distinctly seen in the aestivation, and in the position the 

 leaflets of air-leaves take at night; at night the leaflets close like 

 Mimosa leaves; the lower and upper pair fold up and show dis- 

 tinctlv the short rhachis between them. 



