18 GENERAL REMARKS ON THE 



order, but of which the proper floral envelopes are reduced 

 to a few irregularly placed scales. 



Another Australian genus of Diosmege differs from the 

 rest of the order in having a calyx Avith ten divisions, an 

 equal number of petals, and an indefinite number of stamina 

 with evidently perigynous insertion, 



MYRTACEiE.^ This is one of the most extensive tribes 

 in Terra Australis, in which considerably above 200 species 

 have already been observed, and where the order is also 

 more strikingly modified than in any other part of the 

 world. It is very generally spread over the whole of Aus- 

 tralia, but its maximum appears to be in the principal 

 parallel. Many observations might here with propriety 

 be introduced on the more remarkable structures which 

 occur among the Australian Myrtacese ; I must, however, 

 647] confine myself to a few remarks on the distribution of 

 the most extensive genera. 



Oi Eucalyptus alone nearly 100 species have been already 

 observed ; most of these are trees, many of them of great 

 and some of enormous dimensions. Eucalyptus globulus 

 of Labillardiere and another species peculiar to the south 

 end of Van Diemen's Island, not unfrequently attain the 

 height of 150 feet, with a girth near the base of from 

 25 to 40 feet. In the colony of Port Jackson there are 

 also several species of great size, but none equal to those of 

 Van Diemen's Island ; and no very large trees of this genus 

 were seen either on the south coast or in the equinoctial 

 part of New Holland, Mr. Caley has observed within the 

 limits of the colony of Port Jackson nearly 50 species of 

 Eucalyptus, most of which are distinguished, and have 

 proper names apphed to them, by the native inhabitants, 

 who, from differences in the colour, texture, and scaling of 

 the bark, and in the ramification and general appearance 

 of these trees, more readily distinguish them than botanists 

 have as yet been able to do. Eucalyptus, although so 

 generally spread over the whole of Terra Austrahs, and so 

 abundant as to form at least four fifths of its forests, is 



' Myrti. Jusb. gen. 322, 



