PREFACE. 
This volume, the result of the labour of many years, forms a complete 
Monograph of the extensive order of the MenispermacecB , the structure of 
which was almost unknown when the subject first attracted my attention. 
This investigation was commenced in 1837, during my residence in 
Brazil, and was resumed at intervals after my return home, as oppor- 
tunities presented themselves for examining collections from other parts 
of the world. In 1851 (Ann. Nat. Hist. 2nd ser. vol. vii. p. 33) I sub- 
mitted a general review of the progress made up to that time, and gave 
an outline of the several tribes and genera into which I proposed to 
divide the family, giving, in a short summary, the chief peculiarities of 
the several points of structure on which these divisions were founded ; 
subsequently, having accumulated a sufficient mass of evidence, I com- 
menced in 1864, in the ‘Annals of Natural History,’ the publication of 
the contents of this volume, where, at intermittent periods, the results of 
my investigations were chronicled. The difficulties attendant on the 
acquisition of this amount of information were very great ; for, as it was 
impossible to borrow collections, it became equally impracticable to com- 
pare, side by side, specimens at a distance from one another, and my 
only alternative was to make a tracing of every specimen that came 
beneath my observation, noting upon each its peculiar features, — a tedious 
process, but the only one that could enable me to ascertain the characters 
upon which a valid species was determinable. By this method were 
accumulated upwards of 700 tracings of Menisperniaceous plants; and 
