APPENDIX. No. V. 423 
in the Paper above quoted; a ratio which seems to be confirmed by his own 
extensive herbarium. 
I had remarked, however, in the Essay referred to, that the relative numbers 
of these two primary divisions in the equinoctial parts of New Holland appeared 
to differ considerably from those which I had regarded as general within the 
tropics ; dicotyledones being to monocotyledones only as 4 to 1. But this 
proportion of New Holland very nearly agrees with that of the Congo and 
Sierra Leone collections. And from an examination of the materials com- 
posing Dr. Roxburgh’s unpublished Flora Indica, which I had formerly 
judged of merely by the index of genera and species, I am inclined to think 
that nearly the same proportion exists on the shores of India. 
Though this may be the general proportion of the coasts, and in tracts 
of but little varied surface within the tropics, it seems at the same time pro- 
bable from Baron Humboldt’s extensive collections, and from what we know 
of the vegetation of the West India islands, that in equinoctial America, in 
tracts including a considerable portion of high land, the ratio of dicotyledones 
to monocotyledones is at least that of 11 to 2, or perhaps nearly 6 to 1. 
Whether this or a somewhat diminished proportion of dicotyledones exists 
also in similar regions of other equinoctial countries, we have not yet sufficient 
materials for determining. 
Upon the whole, however, it would seem from the facts of which we are 
already in possession, that the proportions of the two primary divisions of 
phanogamous plants, vary considerably even within the tropics, from cir- 
cumstances connected certainly in some degree with temperature. But there 
are facts also which render it probable, that these proportions are not solely 
dependent on climate. ‘Thus the proportion of the Congo collection, which is 
also that of the equinoctial part of New Holland, is found to exist both in North 
and South Africa, as well as in Van Diemen’s Island, and in the south of Europe, 
It is true indeed that from about 45° as far as to 60°, or perhaps even to 
65° N. lat. there appears to be a gradual diminution in the relative number 
of dicotyledones; but it by no means follows, that in still higher latitudes a 
further reduction of this primary division takes place. On the contrary, it 
seems probable from Chevalier Giesecke’s list of the plants of the west coast of 
Greenland,* on different parts of which, from lat. 60° to 72°, he resided several 
* Article Greenland, in Brewster's Edinburgh Encyclopzdia, 
