APPENDIX. 
530 
Primary Classes.'] 
nogamous in number. In the south of Europe, even making allowance 
for its being at present less perfectly examined, these proportions seem to 
be inverted. And within the tropic, unless at very great heights, Cryp- 
togamous plants appear to form hardly one-fifth of the whole number of 
species. But their proportion in Terra Australis is still smaller than the 
assumed intratropical proportion : for this, however, in the northern parts 
of New Holland at least, the comparative want of shade and moisture* 
conditions essential to the vegetation of several of these tribes, ». ill in some 
measure account; for at the southern extremity of Van Diemen’s Island, 
where the necessary conditions exist, the relative proportion of Cryptoga- 
mous plants is not materially different from that of the south of Europe. 
In that which 1 have called the principal parallel of New Holland, 
however, Cryptogamous plants appear to be much less numerous than in 
the corresponding latitudes of the northern hemisphere; and within the 
tropic they probably do not form more than one-twelfth of the whole num- 
ber of species. 
In several of the islands of the Gulph of Carpentaria, having a Flora 
of PhamogamOus plants exceeding 200 species, 1 did not observe a single 
species of Moss. 
From the three primary classes of plants already treated of I proceed 
at once to those groups called Natural Orders or Families ; for the in- 
termediate divisions are too much at variance with the natural series to 
be made the subject of such general remarks as have been already offered 
on the primary classes, and which are equally admissible with respect to 
the natural families. 
A methodical, and at the same time a natural, arrangement of these 
families is, in the existing state of our knowledge, perhaps impracticable. It 
would probably facilitate its future attainment, ifotpresent, entirely neglect- 
in <T it, attention were turned to the combination of these orders into Classes 
equally natural, and which, on a thorough investigation, might equally admit 
of being defined. The existence of certain natural elassesjs already acknow- 
ledged, and l have, in treating of the Australian natural families, ventured 
to propose a few that are perhaps less obvious, still more however might 
have been suggested had this been the place for pui suing the subject. 
