* INTBODIICTION. 



diagnostic use. These researclies formed to a large measure the basis, on wMch the 

 venerahle Mr. Bentham, with access to all the resources then available, and gradually 

 accumulated since the time of Cook's first voyage, biult up a complete descrlptlTe 

 system of the species of Eucalyptus in 1866 (Flora Australien^is iii., 185-261). 



The primary characteristic for grouping the specific forms (about 140 then 

 being known), which received preference by Mr. Bentham, was derived from the 

 stamens and particularly the anthers ; the systematic arrangement thus devised has 

 also since proved the most convenient for easy working ^\ith Museum-material, so 

 long as it was the main object to ascertain the name of any species. But the method 

 of grouping adopted by him brings also into close contact most of the Eucalypts, 

 which are bound together by natural affinity. Trifling alterations have however 

 suggested themselves during the actual use of this arrangement ; for instance, from 

 the series of "Normales" should be dismembered the subseries of "Comutae," to 

 which, as forming really a distinct ftdl series, the appellation " Orthostemones " might 

 most expressively be apphed ; some further separations from the Normales might 

 aptly be effected still, and perhaps some re-arrangements also, in order to bring all 

 the sections of the genus more into values of equality. It might have been advisable 

 to have adopted this method of arrangement for the Atlas also, and to have numbered 

 the plates accordingly ; but on full consideration it was deemed best, to leave the 

 lithograms purposely unnumbered, as then the author could move more freely in his 

 choice of the species for successive illustration ; moreover, then any one, who had 

 occasion to utilize the Atlas, might unrestrictedly arrange the plates either in 

 accordance with the method derived fr'om the stamens, or according to the cortical 

 system, or at aU events merely alphabetically. The issue of the lithograms, thus 

 independent of each other, necessitated also the printing of the text on separate 

 pages for each species, the whole to be bound up on the completion of the work, 

 when the needful indices could be published also. Several additional well-marked 

 species of Eucalyptus have only been discovered during the last few years, whereas 

 other are hkely yet to be added from still unexplored tracts of Austraha and perhaps 

 the adjoining islands. Any such additional kinds can be inserted at theii* right places 

 into the work, if we remain free from numeric sequence. As however a series of 

 years must necessarily elapse, before the needful funds for the completion of so large a 

 work can gradually be secured, and as moreover plates and text will likely be quoted 

 successively in other publications, it became necessary to adopt at once some form 

 of periodic issue, for which that in decades seemed the most ehgible. Meanwhile the 

 enlightened Government of West Australia is issuing already two decades, pertainine 

 to the leading timber-trees of the great western colony ; and perhaps some of the 

 other colonial Governments may follow this example, to expedite the work, and to 

 relieve our own colony of a portion of the cost of a publication, in which all Austraha 



