PREFACE. 
V 
leaves and involucres. These considerations have been wholly ignored by 
the distinguished author of the Gymnospermous orders in a recent volume 
of the ‘ Prodromus ’ of De Candolle, where their organization is expounded 
upon the very limited views of the older botanists. The many striking 
points of analogy between Ephedra and Casuarina, especially in their habit 
and floral structure, are here sufiiciently indicated to show the considerable 
degree of affinity that exists between them : the details of the seminal 
structure of Casuarina, which I analyzed with great care, will, I think, be 
found more correct than the description lately given by Prof. Miquel in 
the same volume of the ‘ Prodromus.’ 
I have also contributed a monograph of the Tricuspidarieee. 
Many details are given towards a knowledge of the structure of the 
HeliotropiacecB, a description of the new genus Cochranea being added 
and the hitherto doubtful genus Messerschnidtia defined. 
In succession the various South- American forms of the Ehretiaceee have 
been carefully analyzed, especially with regard to their carpical organiza- 
tion and the peculiar development of the ovary and seeds ; at the same 
time the characters of the several genera are amply described, and illus- 
trated by separate drawings. 
The next or third volume of these ‘ Contributions ’ wiU be wholly occu- 
pied by my Monograph of the Menispermacece, which has now been some 
time in type, awaiting the completion of about sixty-five plates, in illus- 
tration of the peculiar structure of each genus of that family. 
84 Addison Road, Kensington. 
October 18G9. 
VOL. 11. 
b 
