210 APPENDIX. 



as well as of those peculiar American orders, which are found both north and south of 

 the limits of this work. 



Altogether, it will be seen, 185 of the 203 natural orders of flowering plants are 

 represented in America, leaving a residue of only eighteen. Six of these are widely 

 spread in the Old World, though mostly characteristic of certain regions ; thus the 

 Nepenthacese of the Malay Archipelago and the Pittosporese of Australia. Three 

 orders are common to Asia and Africa; two to Asia, Australasia, and Polynesia; 

 and one to Australasia and Polynesia. Two are peculiar to Australasia, two to South 

 Africa, and one, the Chlsenacese, to Madagascar. Recent explorations in Madagascar 

 have considerably augmented this remarkable order, eight genera and at least twenty- 

 five species being now known. The only orders not represented in America of great 

 economic importance are the Dipterocarpese and the Pandanese, the former chiefly 

 inhabiting tropical Asia, and the latter specially characteristic of the Mascarene and 

 Malay islands. Pandanus utilis is cultivated in the West Indies. The Cyclanthacese 

 are the New-World counterparts of the Pandaneae. It should be mentioned that a 

 considerable number of distinct tribes and suborders, regarded as independent orders 

 by some botanists, are of much narrower distribution. 



Geneeic Distribution. 



The total number of Phanerogamic genera known to inhabit Mexico and Central 

 America is 1794, and the number of species approximately 11,626, or nearly six to a 

 genus. Their distribution is set forth numerically in the accompanying Tables, which 

 are explained in the succeeding paragraphs. 



It will be convenient to discuss most of the details of the distribution of the genera 

 in connection with the species, as a great deal of repetition will thereby be avoided. The 

 first of the two foregoing Tables (pp. 208-9) shows the distribution of the genera within 

 Mexico and Central America, so far as it is known at present, and requires very little 

 explanation beyond that at p. 169 relating to the larger Table, from which these were 

 reduced. What particularly strikes one are the comparatively small numbers from 

 most of the southern districts — evidence of how much remains to be done. Indeed the 

 only area that has been anything approaching fully investigated is South Mexico ; and 

 North Mexico comes next. As mentioned elsewhere, the numbers in the " uncertain " 

 column may well be added to the South-Mexican, as it is now certain that with very 

 few exceptions they are from that region. Notwithstanding the fact that a very large 

 extent of the country is still almost wholly unexplored botanically, it is not probable 

 that future labours will bring any great accession to the present total number of genera 

 for the whole country, because the number of quite local genera is exceedingly small, 

 as may be gathered from the very low proportion of endemic genera in Central 

 America. Collectively, 23:6 percent, of the genera described inBentham and Hooker's 

 * Genera Plantarum' are found within our limits, and 18*2 per cent, in South Mexico. 



