30 TIII^ VICtOKT.VN TfATURALISt. 



ON THE CDASSIFirATION OF EUCALYPTUS. 

 By Rry. Dn. Woolls, Ph.D.. F.L.S. 



There are sopie genera (<f plants iii wliicli the species may be 

 £>'ronped without (iifflcnltjj They seem to be distinguished by certain 

 characters, and to fall naturally into their proper places. Thus, for 

 instance, iu some of the large ^^enera in tlie Leguminous and 

 Myrtaceous orders, our eminent botanists, Bentham and Mueller , 

 feit no Jiesitation in reducing the species to their respective stations 

 in a systematic arrangement. One large genus, indeed, that of 

 Acacia , (which numbers some oOO species), though, taken as a 

 whole, a most marked one, gave Mr. Bentham much trouble in 

 forming any definite sections, and therefore he regarded his divisions 

 as somewhat provisional, looking forward to a period when the pods 

 of all the species could be procured for comparison and the fuiiicle of 

 the seeds be carefully examined. 



With regard to the subdivision of the genus EiccaJi/pius, 

 he candidly acknowledged, that to the butanist who is unable 

 to compare the various forms in a iJYin.a: state , the due limitation 

 and classification of the species present almost insuperable 

 obstacles. In tlie early days of Australian colonisation, when, 

 in addition to _£'. obiiqua , only eleven species were known to 

 European botanists, (tliose species being noticed in the ini*neiiiate 

 neighbourhood of Port Jackson), it was considered sufficient to 

 divide them according to the shape and length of the opercula 

 which covered the stamens _ in the bud. Thus, Hilldenow (1799) 

 ![ms two .classes, viz., those with conical, and those with hemi- 

 spherical opercula. This classification was followed by R. Brown, 

 (1810), to whom about 100 species were partially known, and with 

 further modifications in regard to the shape and length of tlio 

 opercula , it was adopted by De Caud(il le, Don, i.^-c. When Baron 

 Mueller some tliirty years ago settled in Australia, and had oppor- 

 tunities of examining many species of Eucnh/pfus in a living state , 

 he found that the system of classification /litherto pursued was 

 untenable, seeing that, in some species, the lenRth of tlie opercuhnu 

 was not uniform , "■•hilst in others tlie shape was sometimes conical^ 

 and sometimes hemispherical . This led him to devise what is 

 ;termed the '^ cortical system, " that is, a grouping of species accor- 

 ding to the nature of their res])ective bark s, such, for instance, as 

 . "smootli-bai-Jvii d," ' '' half-dTu-k.^LL " " fibrous-barkod ,'" and " cloeply 

 f urrowed -bax^ad. " trees. 'Iji the Eun^pean botanist, this s^-stem, 

 (thoug'irexti'emely natural and of great use to those who have an 



