BOTANY OF TERRA AUSTRALIS. 9 



tion of Dicotyledones to jMonocotylcdones docs not exceed 

 3 to 1. At the western extremity of the same parallel, 

 in the vicinity of King George's Sound, the proportion is 

 but little different from that of Port Jackson, being nearly 

 as 1 3 to 4. At tlie south end of Van Diemen's Island in 

 43° S. hit., it is fully 4 to 1. And with this proportion 

 that of Carpentaria, and I may add the whole of the cfpii- 

 noctial part of New Holland, hitherto examined, very nearly 

 agrees. 



I confess I can perceive nothing cither in the nature of 

 the soil or clin)ate of Terra Austraiis, or in the circumstances 

 under which our collections were formed, to account for 

 these remarkable exceptions to the general proportions of 

 the two classes in the corresponding latitudes of other 

 countries. 



With regard to the proportion of Acotyledones in Terra 

 Austraiis, it is necessary to premise that I consider my collec- 

 tions of some of the Cryptogamous order, especially of Fungi, 

 as very imperfect. If, however, 300 species were added to the 

 400 actually collected, I beheve it would give an approxi- 

 mation to the true proportions, which on this supposition, 

 would be of Phsenogamous to Cryptogamous plants as 

 nearly 11 to 2. But the general proportion of these two 

 great divisions, as deduced from the published materials, is 

 very different from thi«. being nearly 7 to 2. 



If we inquire in what degree these proportions are 

 dependent on climate, we find that in the more northern 

 parts of Europe, as in Lapland and even in Great Britain, 

 Cryptogamous plants somewhat exceed the Phtenogamous 

 in number. In the south of Europe, even making allow- [539 

 ance for its being at present less perfectly examined, these 

 proportions seem to be inverted. And within the troj)ic, 

 unless at veiy great heights, Cryptogamous plants appear 

 to form hardly one fifth of the whole number of sj)ecies. 

 But their proportion in Terra Austraiis is still smaller than 

 the assumed intratropical proportion : for this, however, in 

 the northern parts of New Ilolland at least, the comparative 

 want of shade and moisture, conditions essential to the 

 vegetation of several of these tribes, will in some measure 



