by the believers in the 'Methode Mononomique,' that they do not intend to ignore the _arrangement_ which Nature has so broadly laid down, but that, on the contrary, they tacitly endorse it,--their device having reference to the _names_ only. To this however it will be sufficient to reply, that, if they deem it necessary (of which I am by no means convinced) to accept the natural genera of the organic creation at all, why not _acknowledge_ them? and how can they be so well acknowledged, either in principle or practice, as through the medium of a binomial nomenclature? Such a system is the only consistent one, on the hypothesis that they _do_ consider them of primary importance; it is more in unison with our notions of what ought to be; more suggestive of what actually _is_; more honest and generous to those who have laboured (as describers), with such care and diligence, before us. It will be perceived, from the above remarks, that, although professedly criticizing the 'Methode Mononomique,' into the analysis of which my subject has unintentionally drawn me, it is the absurdity of objecting to genera _because they are not rigidly defined throughout_, that I have been mainly striving to condemn. It is indeed well nigh incredible that any such strictures could ever have been advanced; for it must surely have occurred to the most superficial inquirer, that genera, after all, _cannot_ be homogeneous,--seeing that they are necessarily composed of detached species, no two of which are _precisely_ similar, even in the few structural details which may have been accidentally chosen for generic diagnostics. How is it possible, therefore, that mere _groups_, even though they be in accordance with Nature, should be so far isolated and uniform in their character as to occupy an analogous position to that of the absolutely independent species (of distinct origins) which they severally contain?