438 M. A. DeCandoUe on the Characters ivhich distinguish 



Anser segetum, Steph. Sula alba, Temm. 



Mareca Penelope, Selb. Procellaria mollis, Gould. 



Anas crecca, Linn. Pacifica, And. 



♦Sterna hirimdo, Linn. *Puffinus major, Temm. 



nigra, Linn. * Auglorum, Temm. 



Dougalli, Mont. * obscurus, Temm. 



*Larus argentatus, Brunn. *Tbalassidi-oma Buhverii, Jard. 



tridactylns. Lath. * Leaebii, Temm. 



Lestris cataractes, Temm. pelagica, Temm. 



CohTnbus glacialis, Linn. 



I have the honour to remain, Gentlemen, 

 Your obedient servant, 



Edward Yernon Harcourt. 

 20 Portland Place, London, 

 Mav 11, 1855. 



XXXIX. — On the Characters ivhich distinguish the Vegetation of 

 a Country. By M. Alphonse DeCaxdolle*. 



The vegetation of any particular country or district always pre- 

 sents more or less important and distinct characters. These are 

 numerous ; and few authors in writing Floras, or memoirs on 

 botanical geography, ever think of enumerating the whole of 

 them, still less of regarding them according to their actual 

 degree of importance. 



These characters relate to the conditions of the classes, or 

 great divisions of the vegetable kingdom, the families, genera 

 and species, in the country treated of, and also to the analogies 

 and differences presented by them in comparison with other 

 regions. The following enumeration will show the multiplicity 

 of these points. 



I. Enumeration of the Characters. 



1. Characters relating to Classes. 



Proportion of Phanerogamia and Cri/ptogamia. — In the actual 

 state of our knowledge it is of very little use to seek to determine 

 this proportion ; and, moreover, if we knew it elsewhere than in 

 Europe, it is doubtful whether it would present any true interest. 

 The species being ill-defined and imperfectly known amongst the 

 Cryptogamia, and the structure, appearance and position of 

 these plants being extremely diverse, and usually without 

 analogy with those of the Phanerogamia, it is difficult to say 

 what would be the object or the result of such a comparison. 



Proportion of Dicotyledones and Monocotyledones. — Few 

 numerical data are so frequently given in botanical geography, 

 and yet this proportion is usually inexact, and not very important 

 to be known. 



* From the Bibliotheque Universelle de Geneve for December 1854. 



